Журнал вычислительной математики и математической физики, 2023, T. 63, № 2, стр. 282-316
Локальная разрешимость, разрушение и гёльдеровская регулярность решений некоторых задач Коши для нелинейных уравнений теории волн в плазме. II. Теория потенциала
М. О. Корпусов 1, *, Е. А. Овсянников 1, **
1 МГУ им. М.В. Ломоносова
119991 Москва, Ленинские горы, 1, Россия
* E-mail: korpusov@gmail.com
** E-mail: evg.bud@yandex.ru
Поступила в редакцию 29.11.2021
После доработки 04.07.2022
Принята к публикации 04.07.2022
- EDN: BOJJQG
- DOI: 10.31857/S0044466923020102
Аннотация
В статье рассматриваются объемный и поверхностный потенциалы, возникающие в задачах Коши для нелинейных уравнений из теории ионно-звуковых и дрейфовых волн в плазме, и изучаются их свойства. Для объемного потенциала выводится некоторая оценка. На ее основе доказываются одна априорная оценка типа Шаудера и оценки типа Шаудера для потенциалов с весом. Библ. 5.
1. ОБЪЕМНЫЙ И ПОВЕРХНОСТНЫЙ ПОТЕНЦИАЛЫ В ПРОСТРАНСТВАХ ГЁЛЬДЕРА
Стоит отметить, что настоящая статья является логическим продолжением работы [1], в ней продолжаются исследования, начатые ранее в [1].
Рассмотрим следующие объемный и поверхностный потенциалы:
(1.1)
$U(x,t) = U[\rho ](x,t) = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} {\kern 1pt} {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau ,$(1.2)
${{V}_{k}}(x,t) = {{V}_{k}}[\mu ](x,t) = \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{k}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t)}}{{\partial {{t}^{k}}}}\mu (y){\kern 1pt} dy,\quad k \in \mathbb{N} \cup \{ 0\} ,$(1.3)
${{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t) = \frac{{{{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\mathcal{E}(x - y,t),\quad {{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0,$Теорема 1. Если $\rho (x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}}))$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0,$ то
и справедлива следующая оценка:Доказательство.
Шаг 1: $U(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$ Пусть $\rho (x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}}))$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0.$ Объемный потенциал $U(x,t)$ можно представить в следующем виде:
(1.4)
$U(x,t) = \int\limits_0^t \,H(x,t,\tau ){\kern 1pt} d\tau ,\quad H(x,t,\tau ) = \int\limits_{{{\mathbb{R}}^{3}}} {\kern 1pt} {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )\rho (y,\tau ){\kern 1pt} dy.$(1.5)
$\begin{gathered} \left| {H({{x}^{1}},{{t}^{1}},{{\tau }^{1}}) - H({{x}^{2}},{{t}^{2}},{{\tau }^{2}})} \right|\;\leqslant \;\left| {{{H}_{1}}({{x}^{1}},{{t}^{1}},{{\tau }^{1}})} \right| + \left| {{{H}_{1}}({{x}^{2}},{{t}^{2}},{{\tau }^{2}})} \right| + \\ \, + \left| {{{H}_{2}}({{x}^{1}},{{t}^{1}},{{\tau }^{1}})} \right| + \left| {{{H}_{2}}({{x}^{2}},{{t}^{2}},{{\tau }^{2}})} \right| + \left| {{{H}_{3}}({{x}^{1}},{{t}^{1}},{{\tau }^{1}}) - {{H}_{3}}({{x}^{2}},{{t}^{2}},{{\tau }^{2}})} \right|, \\ \end{gathered} $(1.6)
$\begin{gathered} \left| {{{H}_{3}}({{x}^{1}},{{t}^{1}},{{\tau }^{1}}) - {{H}_{3}}({{x}^{2}},{{t}^{2}},{{\tau }^{2}})} \right|\;\leqslant \\ \leqslant \;\int\limits_{O(0,{{R}_{\delta }})\backslash O(0,{{r}_{\delta }})} \left| {\frac{{{{{(1\; + \;{\text{|}}{{x}^{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1\; + \;{\text{|}}z + {{x}^{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\mathcal{E}(z,{{t}^{1}} - {{\tau }^{1}}) - \frac{{{{{(1\; + \;{\text{|}}{{x}^{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1\; + \;{\text{|}}z + {{x}^{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\mathcal{E}(z,{{t}^{2}} - {{\tau }^{2}})} \right|dz < \frac{\delta }{3} \\ \end{gathered} $(1.7)
$\left| {({{x}^{1}},{{t}^{1}},{{\tau }^{1}}) - ({{x}^{2}},{{t}^{2}},{{\tau }^{2}})} \right| < \eta (\delta )$(1.8)
$\begin{gathered} \left| {H(x,t,\tau )} \right|\;\leqslant \;\left( {\mathop {\sup }\limits_{(x,t) \in {{\mathbb{R}}^{3}} \times [0,T]} {\text{|}}\rho (x,t){\kern 1pt} {\text{|}}} \right)\left( {{{I}_{1}} + {{I}_{2}}} \right), \\ {{I}_{1}} = (1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}\int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{0}})} \frac{{\left| {\mathcal{E}(x - y,t - \tau )} \right|}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy,\quad {{I}_{2}} = (1\; + \;{\text{|}}x{{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}\int\limits_{O(x,{{R}_{0}})} \frac{{\left| {\mathcal{E}(x - y,t - \tau )} \right|}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy. \\ \end{gathered} $(1.9)
${{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\;\leqslant \;{{2}^{{{{\beta }_{1}}/4}}}{{(1\; + \;{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}.$(1.10)
${{I}_{2}}\;\leqslant \;{{M}_{6}}(T,{{R}_{0}},\varepsilon )\int\limits_{O(x,{{R}_{0}})} \frac{{{{{(1\; + \;{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{\text{|}}x - y{\kern 1pt} {\text{|}}}}\frac{1}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy\;\leqslant \;{{M}_{7}}(T,{{R}_{0}},\varepsilon ) < + \infty .$Шаг 2: ${{U}_{{{{x}_{j}}}}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$ Докажем, что
(1.11)
$\frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.12)
$\frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}} = \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{x}_{j}}}}\rho (y,\tau ){\kern 1pt} dy.$(1.13)
$H(x,t,\tau ) = \int\limits_{{{\mathbb{R}}^{3}}\backslash O(0,2{{R}_{0}})} {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,t,t - \tau )\rho (y,\tau ){\kern 1pt} dy + \int\limits_{O(0,2{{R}_{0}})} {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,t,t - \tau )\rho (y,\tau ){\kern 1pt} dy = {{J}_{1}} + {{J}_{2}}.$(1.14)
$\frac{{\partial {{J}_{2}}}}{{\partial {{x}_{j}}}}\int\limits_{O(0,2{{R}_{0}})} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,t,t - \tau )}}{{\partial {{x}_{j}}}}\rho (y,\tau ){\kern 1pt} dy.$(1.17)
$\frac{{\partial {{J}_{1}}}}{{\partial {{x}_{j}}}}\int\limits_{{{\mathbb{R}}^{3}}\backslash O(0,2{{R}_{0}})} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,t,t - \tau )}}{{\partial {{x}_{j}}}}\rho (y,\tau ){\kern 1pt} dy.$(1.18)
$\mathop {\sup }\limits_{(x,\tau ,t) \in {{\mathbb{R}}^{3}} \times \{ 0\leqslant \tau \leqslant t\leqslant T\} } \left| {\frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}}} \right| < + \infty .$(1.19)
$\frac{{\partial U(x,t)}}{{\partial {{x}_{j}}}} = \int\limits_0^t \frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}}{\kern 1pt} d\tau .$(1.20)
$\begin{gathered} {{J}_{4}} = \frac{{U({{x}_{h}},t) - U(x,t)}}{h} - \int\limits_0^t \frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}}{\kern 1pt} d\tau = \int\limits_0^t \left[ {\frac{{H({{x}_{h}},t,\tau ) - H(x,t,\tau )}}{h} - \frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}}} \right]{\kern 1pt} d\tau = \\ \, = \int\limits_0^t \left[ {\frac{{\partial H(x{\kern 1pt} *,t,\tau )}}{{\partial {{x}_{j}}}} - \frac{{\partial H(x,t,\tau )}}{{\partial {{x}_{j}}}}} \right]{\kern 1pt} d\tau \quad {\text{при}}\quad x{\kern 1pt} * \in {\text{|}}x,{{x}_{h}}{\text{|}}. \\ \end{gathered} $(1.21)
$\frac{{\partial U(x,t)}}{{\partial {{x}_{j}}}} = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{x}_{j}}}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$Шаг 3: ${{U}_{t}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$
Докажем, что
(1.22)
$\frac{{\partial H(x,t,\tau )}}{{\partial t}} = \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}\rho (y,\tau ){\kern 1pt} dy.$(1.23)
$\begin{gathered} = \int\limits_{{{\mathbb{R}}^{3}}\backslash O(0,2{{R}_{0}})} \left[ {\frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t{\kern 1pt} * - \;\tau )}}{{\partial t}} - \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}} \right]\rho (y,\tau ){\kern 1pt} dy,\quad t{\kern 1pt} * \in {\text{|}}t,t + h{\kern 1pt} {\text{|,}} \\ {{H}_{1}} = \int\limits_{O(x,N{{R}_{0}})\backslash O(x,2{{R}_{0}})} \left[ {\frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t{\kern 1pt} * - \;\tau )}}{{\partial t}} - \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}} \right]\rho (y,\tau ){\kern 1pt} dy + \\ \end{gathered} $(1.24)
${\text{|}}{{H}_{{11}}}{\kern 1pt} {\text{|}}\;\leqslant \;\mathop {\sup }\limits_{(x,t) \in {{\mathbb{R}}^{3}} \times [0,T]} {\text{|}}\rho (x,t){\text{|}}\int\limits_{O(x,N{{R}_{0}})\backslash O(x,\delta )} \left| {\frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t{\kern 1pt} * - \;\tau )}}{{\partial t}} - \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}} \right|dy < \frac{\eta }{3},$Рассуждая точно так же, как на шаге 1, с учетом оценок (6.7) и (6.9) статьи [1], а также оценки интеграла (10. 20) из [1] мы можем доказать, что
(1.25)
$\frac{{\partial H(x,t,\tau )}}{{\partial t}} = \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}\rho (y,\tau ){\kern 1pt} dy \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ),$(1.26)
$\mathop {\sup }\limits_{(x,t,\tau ) \in {{\mathbb{R}}^{3}} \times \{ 0\leqslant \tau \leqslant t\leqslant T\} } \left| {\frac{{\partial H(x,t,\tau )}}{{\partial t}}} \right| < + \infty .$(1.27)
$\frac{{\partial U(x,t)}}{{\partial t}} = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$(1.28)
$\frac{{\partial U(x,t)}}{{\partial t}} = \int\limits_0^t \frac{{\partial H(x,t,\tau )}}{{\partial t}}{\kern 1pt} d\tau .$(1.29)
$\begin{gathered} {{U}_{1}} = \frac{{U(t + h,x) - U(t,x)}}{h} - \int\limits_0^t \frac{{\partial H(x,t,\tau )}}{{\partial t}}{\kern 1pt} d\tau = \frac{1}{h}\int\limits_0^{t + h} H(x,t + h,\tau ){\kern 1pt} d\tau - \frac{1}{h}\int\limits_0^t H(x,t,\tau ){\kern 1pt} d\tau = \\ = \frac{1}{h}\int\limits_t^{t + h} H(x,t + h,\tau ){\kern 1pt} d\tau + \int\limits_0^t \left[ {\frac{{H(x,t + h,\tau ) - H(x,t,\tau )}}{h} - \frac{{\partial H(x,t,\tau )}}{{\partial t}}} \right]{\kern 1pt} d\tau = {{U}_{{11}}} + {{U}_{{12}}}. \\ \end{gathered} $(1.30)
${{U}_{{12}}} = \int\limits_0^t \left[ {\frac{{\partial H(x,t*,\tau )}}{{\partial t}} - \frac{{\partial H(x,t,\tau )}}{{\partial t}}} \right]{\kern 1pt} d\tau \to 0\quad {\text{при}}\quad h \to 0,$Шаг 4: ${{U}_{{{{x}_{j}}t}}}(x,t) = {{U}_{{t{{x}_{j}}}}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T])$.
Из поточечного равенства (1.21), рассуждая точно так же, как на шаге 3, можно доказать, что справедливо поточечное равенство
(1.31)
$\begin{gathered} \frac{{{{\partial }^{2}}U(x,t)}}{{\partial t\partial {{x}_{j}}}} = \int\limits_0^t \frac{{{{\partial }^{2}}H(x,t,\tau )}}{{\partial t\partial {{x}_{j}}}}{\kern 1pt} d\tau = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t\partial {{x}_{j}}}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau , \\ \frac{{{{\partial }^{2}}H(x,t,\tau )}}{{\partial t\partial {{x}_{j}}}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ), \\ \end{gathered} $(1.32)
$\frac{{{{\partial }^{2}}U(x,t)}}{{\partial {{x}_{j}}\partial t}} = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{x}_{j}}\partial t}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau .$(1.33)
$\frac{{{{\partial }^{2}}U(x,t)}}{{\partial t\partial {{x}_{j}}}} = \frac{{{{\partial }^{2}}U(x,t)}}{{\partial {{x}_{j}}\partial t}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$Шаг 5: ${{U}_{{tt}}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T])$.
Используя доказанное на шаге 3 поточечное равенство (1.27), точно так же, как на шаге 3, можно доказать, что справедливо следующее поточечное равенство:
(1.34)
$\frac{{{{\partial }^{2}}U(x,t)}}{{\partial {{t}^{2}}}} = - \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\frac{{\exp ( - {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\rho (y,t){\kern 1pt} dy + \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{t}^{2}}}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau .$Шаг 6: ${{U}_{{{{x}_{j}}{{x}_{k}}}}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T])$.
Поскольку $\rho (x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})),$ то с учетом (3.1) и (4.8) справедливо поточечное равенство
(1.35)
$\begin{gathered} \times \;\int\limits_{{{\mathbb{R}}^{3}}} \mathcal{E}(x - y,t - \tau )\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + {{\beta }_{1}}{{x}_{k}}{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t - \tau )}}{{\partial {{x}_{j}}}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \, + {{\beta }_{1}}{{x}_{j}}{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t - \tau )}}{{\partial {{x}_{k}}}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \end{gathered} $(1.36)
$ + \int\limits_{O(x,{{R}_{\delta }})\backslash O(x,{{r}_{\delta }})} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + $(1.37)
${{L}_{1}}(x,t,\tau ) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.38)
${{L}_{2}}(x,t,\tau ),\;{{L}_{3}}(x,t,\tau ) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.39)
$\begin{gathered} \frac{{\left| {{{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|}}{{{\text{|}}x - y{\kern 1pt} {\text{|}}}}\;\leqslant \;3{{\beta }_{1}},\quad {{\beta }_{1}} \in [0,1], \\ \frac{{\left| {{{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|}}{{{\text{|}}x - y{\kern 1pt} {\kern 1pt} {\text{|}}}}\;\leqslant \;3{{\beta }_{1}}{{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1\; + \;{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}},\quad {{\beta }_{1}} > 1. \\ \end{gathered} $(1.40)
${\text{|}}x{\kern 1pt} {\text{|}}\frac{{{{\partial }^{2}}\mathcal{E}(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}}} \in {{\mathbb{C}}^{{(m + n)}}}({{\mathbb{R}}^{3}}{{\backslash }}\{ 0\} \times [0, + \infty ))\quad {\text{для}}\;{\text{всех}}\quad m,n \in \mathbb{N} \cup \{ 0\} .$(1.41)
${{L}_{{41}}}(x,t,\tau ) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.42)
$\begin{gathered} {\text{|}}{{L}_{{43}}}{\text{|}}\;\leqslant \;\mathop {\sup }\limits_{(x,t) \in {{\mathbb{R}}^{3}} \times [0,T]} {{M}_{{13}}}(T,{{R}_{0}},\varepsilon )\int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \frac{{\exp ( - (1 - \varepsilon ){\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{{\text{|}}x - y{\kern 1pt} {\text{|}}}}{\kern 1pt} dy\;\leqslant \\ \leqslant \;{{M}_{{14}}}(T,{{R}_{0}},\varepsilon )\int\limits_{{{R}_{\delta }}}^{ + \infty } {\kern 1pt} \rho \exp ( - (1 - \varepsilon )\rho ){\kern 1pt} d\rho < \frac{\delta }{4}, \\ \end{gathered} $(1.43)
$\begin{gathered} {\text{|}}{{L}_{{44}}}{\kern 1pt} {\text{|}}\;\leqslant \;{{\left[ {\frac{{\rho (x,t)}}{{{{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}} - {{\beta }_{1}}}}}}}} \right]}_{\alpha }}\int\limits_{O(x,{{r}_{\delta }})} {\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{\alpha }}\left| {\frac{{{{\partial }^{2}}}}{{\partial {{y}_{j}}\partial {{y}_{k}}}}\mathcal{E}(x - y,t - \tau )} \right|{\kern 1pt} dy\;\leqslant \\ \leqslant \;{{M}_{{15}}}(T,{{R}_{0}},\varepsilon )\mathop {\sup }\limits_{t \in [0,T]} {{\left| {\rho (x,t)} \right|}_{\alpha }}\int\limits_{O(x,{{r}_{\delta }})} \frac{1}{{{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{{3 - \alpha }}}}}{\kern 1pt} dy\;\leqslant \;{{M}_{{16}}}(T,{{R}_{0}},\varepsilon )r_{\delta }^{\alpha } < \frac{\delta }{4}. \\ \end{gathered} $(1.44)
${{L}_{{42}}}(x,t,\tau ) + {{L}_{{43}}}(x,t,\tau ) + {{L}_{{44}}}(x,t,\tau ) + {{L}_{{45}}}(x,t,\tau ) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.45)
$\frac{{{{\partial }^{2}}H(x,t,\tau )}}{{\partial {{x}_{j}}\partial {{x}_{k}}}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.46)
$\frac{{{{\partial }^{2}}H(x,t,\tau )}}{{\partial {{x}_{j}}\partial {{x}_{k}}}} = \frac{{{{\partial }^{2}}H(x,t,\tau )}}{{\partial {{x}_{k}}\partial {{x}_{j}}}}.$Шаг 7: ${{U}_{{t{{x}_{j}}{{x}_{k}}}}}(x,t) = {{U}_{{{{x}_{j}}t{{x}_{k}}}}}(x,t) = {{U}_{{{{x}_{j}}{{x}_{k}}t}}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$
Прежде всего заметим, что справедливо поточечное равенство (1.22)
(1.47)
$\begin{gathered} \times \;\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t - \tau )}}{{\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + {{\beta }_{1}}{{x}_{k}}{{(1\; + \;{\text{|}}x{{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{x}_{j}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \, + {{\beta }_{1}}{{x}_{j}}{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{x}_{k}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \end{gathered} $(1.48)
$ + \;\int\limits_{O(x,{{R}_{\delta }})\backslash O(x,{{r}_{\delta }})} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + $(1.49)
$\begin{gathered} \frac{{{{\partial }^{3}}H(x,t,\tau )}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ), \\ \frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}} = \int\limits_0^t \frac{{{{\partial }^{3}}H(x,t,\tau )}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}}{\kern 1pt} d\tau = \int\limits_0^t \frac{{{{\partial }^{2}}}}{{\partial {{x}_{j}}\partial {{x}_{k}}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]). \\ \end{gathered} $(1.50)
$\begin{gathered} \, \times \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t - \tau )}}{{\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + {{\beta }_{1}}{{x}_{k}}{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{x}_{j}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \, + {{\beta }_{1}}{{x}_{j}}{{(1\; + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{x}_{k}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1\; + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \end{gathered} $(1.51)
$ + \;\int\limits_{O(x,{{R}_{\delta }})\backslash O(x,{{r}_{\delta }})} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}\partial t}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + $(1.52)
$\frac{{{{\partial }^{3}}H(x,t,\tau )}}{{\partial t\partial {{x}_{j}}\partial {{x}_{k}}}} = \frac{{{{\partial }^{3}}H(x,t,\tau )}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.53)
$\frac{{{{\partial }^{3}}U(x,t)}}{{\partial t\partial {{x}_{j}}\partial {{x}_{k}}}} = \frac{{{{\partial }^{2}}H(x,t,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}}} + \int\limits_0^t \frac{{{{\partial }^{3}}H(x,t,\tau )}}{{\partial t\partial {{x}_{j}}\partial {{x}_{k}}}}{\kern 1pt} d\tau ,$Шаг 8: ${{U}_{{{{x}_{j}}tt}}}(x,t) = {{U}_{{t{{x}_{j}}t}}}(x,t) = {{U}_{{tt{{x}_{j}}}}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T])$.
Точно так же, как на шаге 2, используя равенство (1.34), с учетом оценок (6.7) и (6.10) статьи [1] можно получить поточечное равенство
(1.54)
$\begin{gathered} \frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{t}^{2}}\partial {{x}_{j}}}} = - \int\limits_{{{\mathbb{R}}^{3}}} \frac{\partial }{{\partial {{x}_{j}}}}\left( {\frac{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}} \right)\rho (y,t){\kern 1pt} dy + \\ \, + \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{3}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{t}^{2}}\partial {{x}_{j}}}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]). \\ \end{gathered} $(1.55)
$\frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{t}^{2}}\partial {{x}_{j}}}} = \frac{{{{\partial }^{3}}U(x,t)}}{{\partial t\partial {{x}_{j}}\partial t}}.$(1.56)
$\frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{t}^{2}}\partial {{x}_{j}}}} = \frac{{{{\partial }^{3}}U(x,t)}}{{\partial t\partial {{x}_{j}}\partial t}} = \frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{x}_{j}}\partial {{t}^{2}}}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$Шаг 9: ${{U}_{{{{x}_{j}}{{x}_{k}}tt}}}(x,t) = {{U}_{{{{x}_{j}}t{{x}_{k}}t}}}(x,t) = $ ${{U}_{{{{x}_{j}}tt{{x}_{k}}}}} = {{U}_{{t{{x}_{j}}{{x}_{k}}t}}}(x,t) = {{U}_{{t{{x}_{j}}t{{x}_{k}}}}}(x,t) = $ ${{U}_{{tt{{x}_{j}}{{x}_{k}}}}}(x,t) \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T])$.
Из формулы (1.34), используя оценки (6.7)–(6.11) статьи [1], точно так же, как на шаге 7, можно доказать поточечное равенство
(1.57)
$\begin{gathered} \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial {{t}^{2}}}} = - \frac{{{{\partial }^{2}}}}{{\partial {{x}_{j}}\partial {{x}_{k}}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\rho (y,t){\kern 1pt} dy + \\ \, + \int\limits_0^t \frac{{{{\partial }^{2}}}}{{\partial {{x}_{j}}\partial {{x}_{k}}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{t}^{2}}}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau , \\ \end{gathered} $(1.58)
$ \times \;\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + {{\beta }_{1}}{{x}_{k}}{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \left( {\frac{\partial }{{\partial {{x}_{j}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}} \right)\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + $(1.59)
$\begin{gathered} + \;\int\limits_{O(x,{{R}_{\delta }})\backslash O(x,{{r}_{\delta }})} \left( {\frac{{{{\partial }^{2}}}}{{\partial {{y}_{j}}\partial {{y}_{k}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}} \right)\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \\ \, + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \left( {\frac{{{{\partial }^{2}}}}{{\partial {{y}_{j}}\partial {{y}_{k}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\text{|}}{\kern 1pt} }}} \right)\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \\ \end{gathered} $(1.60)
$\begin{gathered} \times \;\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{t}^{2}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + {{\beta }_{1}}{{x}_{k}}{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{x}_{j}}\partial {{t}^{2}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \, + {{\beta }_{1}}{{x}_{j}}{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{x}_{k}}\partial {{t}^{2}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \end{gathered} $(1.61)
$ + \;\int\limits_{O(x,{{R}_{\delta }})\backslash O(x,{{r}_{\delta }})} \frac{{{{\partial }^{4}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}\partial {{t}^{2}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \frac{{{{\partial }^{4}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{y}_{j}}\partial {{y}_{k}}\partial {{t}^{2}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + $(1.62)
$\frac{{{{\partial }^{2}}}}{{\partial {{x}_{j}}\partial {{x}_{k}}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\rho (y,t){\kern 1pt} dy \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]),$(1.63)
$\frac{{{{\partial }^{2}}}}{{\partial {{x}_{j}}\partial {{x}_{k}}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{t}^{2}}}}\rho (y,\tau ){\kern 1pt} dy \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times \{ 0\;\leqslant \;\tau \;\leqslant \;t\;\leqslant \;T\} ).$(1.64)
$\begin{gathered} \times \;\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{t}^{2}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + {{\beta }_{1}}{{x}_{k}}{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{t}^{2}}\partial {{x}_{j}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \, + {{\beta }_{1}}{{x}_{j}}{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{3}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{t}^{2}}\partial {{x}_{k}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy + \\ \end{gathered} $(1.65)
$ + \;\int\limits_{O(x,{{R}_{\delta }})\backslash O(x,{{r}_{\delta }})} \frac{{{{\partial }^{4}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{t}^{2}}\partial {{y}_{j}}\partial {{y}_{k}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{\delta }})} \frac{{{{\partial }^{4}}\mathcal{E}(x - y,t - \tau )}}{{\partial {{t}^{2}}\partial {{y}_{j}}\partial {{y}_{k}}}}\frac{{\rho (y,\tau )}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}{\kern 1pt} dy + $(1.66)
$\frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{t}^{2}}\partial {{x}_{j}}\partial {{x}_{k}}}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial {{t}^{2}}}} \in {{\mathbb{C}}_{b}}({{\mathbb{R}}^{3}} \times [0,T]).$(1.67)
$\begin{gathered} \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{t}^{2}}\partial {{x}_{j}}\partial {{x}_{k}}}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial t\partial t\partial {{x}_{j}}\partial {{x}_{k}}}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial t\partial {{x}_{j}}\partial t\partial {{x}_{k}}}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial t\partial {{x}_{j}}\partial {{x}_{k}}\partial t}}, \\ \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial {{t}^{2}}}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t\partial t}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial t\partial {{x}_{k}}\partial t}} = \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial t\partial t\partial {{x}_{k}}}}. \\ \end{gathered} $Лемма 1.1. Если $\rho (x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}}))$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0,$ то потенциал $U(x,t) \in \mathbb{C}_{b}^{{(2 + 2)}}({{\mathbb{R}}^{3}} \times [0,T])$.
Шаг 10: $U(x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}})).$
Из теоремы 8 для каждого $t \in [0,T]$ и $\alpha \in (0,1)$ справедливы соотношения
(1.68)
$\begin{gathered} U(x,t) \in {{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}}), \\ \frac{{\partial U(x,t)}}{{\partial t}} = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial {{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial t}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau \in {{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}}). \\ \end{gathered} $(1.69)
$U(x,{{t}_{2}}) - U(x,{{t}_{1}}) = \int\limits_{{{t}_{1}}}^{{{t}_{2}}} \frac{{\partial U(x,t)}}{{\partial t}}{\kern 1pt} dt\quad {\text{для}}\;{\text{всех}}\quad 0\;\leqslant \;{{t}_{1}}\;\leqslant \;{{t}_{2}}\;\leqslant \;T.$(1.70)
${{\left| {U(x,{{t}_{2}}) - U(x,{{t}_{1}})} \right|}_{{2 + \alpha }}}\;\leqslant \;\int\limits_{{{t}_{1}}}^{{{t}_{2}}} {{\left| {\frac{{\partial U(x,t)}}{{\partial t}}} \right|}_{{2 + \alpha }}}{\kern 1pt} dt\quad {\text{для}}\;{\text{всех}}\quad 0\;\leqslant \;{{t}_{1}}\;\leqslant \;{{t}_{2}}\;\leqslant \;T,$Шаг 11: $U(x,t) \in {{\mathbb{C}}^{{(1)}}}([0,T];{{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}}))$.
Заметим, что справедливо равенство (1.34), которое можно переписать в следующем виде:
(1.72)
$\begin{gathered} W(x,t) = - \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}\frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\rho (y,t){\kern 1pt} dy, \\ {{U}_{2}}(x,t) = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}{{G}_{{{{\beta }_{1}},{{\beta }_{2}}}}}(x,y,t - \tau )}}{{\partial {{t}^{2}}}}\rho (y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau . \\ \end{gathered} $(1.74)
$\mathop {\sup }\limits_{t \in [0,T]} {\text{|}}W(x,t){\kern 1pt} {{{\text{|}}}_{{2 + \alpha }}}\;\leqslant \;{{b}_{2}}\mathop {\sup }\limits_{t \in [0,T]} {\text{|}}\rho (x,t){\kern 1pt} {{{\text{|}}}_{\alpha }},$(1.75)
$\mathop {\sup }\limits_{t \in [0,T]} {\text{|}}{{U}_{2}}(x,t){\kern 1pt} {{{\text{|}}}_{{2 + \alpha }}}\;\leqslant \;{{b}_{3}}(T)\mathop {\sup }\limits_{t \in [0,T]} {\text{|}}\rho (x,t){\kern 1pt} {{{\text{|}}}_{\alpha }}.$(1.76)
$\frac{{{{\partial }^{2}}U(x,t)}}{{\partial {{t}^{2}}}} \in {{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}})\quad {\text{для}}\;{\text{всех}}\quad t \in [0,T].$(1.78)
$ + \;\sum\limits_{j,k = 1,1}^{3,3} {{\left| {\frac{{{{\partial }^{3}}U(x,t{\kern 1pt} *{\kern 1pt} *{\kern 1pt} *)}}{{\partial t\partial {{x}_{j}}\partial {{x}_{k}}}} - \frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}}} \right|}_{\alpha }}\;\leqslant \;\mathop {\sup }\limits_{s \in |t,t + h|} {{\left| {\frac{{\partial U(x,s)}}{{\partial t}} - \frac{{\partial U(x,t)}}{{\partial t}}} \right|}_{0}} + $(1.79)
${{I}_{1}} \to 0,\quad {{I}_{2}} \to 0\quad {\text{при}}\quad {\text{|}}h{\kern 1pt} {\text{|}} \to + 0.$(1.80)
$\frac{{{{\partial }^{3}}U(x,s)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}} - \frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}} = \int\limits_{|s,t|} \frac{{{{\partial }^{4}}U(x,\tau )}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial {{\tau }^{2}}}}{\kern 1pt} d\tau ,$(1.81)
$\frac{{{{\partial }^{3}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial t}},\quad \frac{{{{\partial }^{4}}U(x,t)}}{{\partial {{x}_{j}}\partial {{x}_{k}}\partial {{t}^{2}}}} \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})\quad {\text{для}}\;{\text{любого}}\quad t \in [0,T].$Шаг 12: $U(x,t) \in {{\mathbb{C}}^{{(2)}}}([0,T];{{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}}))$.
Заметим, что справедливо равенство (1.71). При этом в силу оценки (3.77) и соотношения (1.73) имеют место следующие соотношения:
(1.83)
$\begin{gathered} W(x,t) \in {{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}})\quad {\text{для}}\;{\text{всех}}\quad t \in [0,T],\quad \alpha \in (0,1), \\ {{\left| {W(x,{{t}_{2}}) - W(x,{{t}_{1}})} \right|}_{{2 + \alpha }}}\;\leqslant \;{{b}_{2}}(T){{\left| {\rho (x,{{t}_{2}}) - \rho (x,{{t}_{1}})} \right|}_{\alpha }} \to + 0 \\ \end{gathered} $(1.84)
$\frac{{\partial {{U}_{2}}(x,t)}}{{\partial t}} \in \mathbb{C}_{b}^{{(2 + 0)}}({{\mathbb{R}}^{3}} \times [0,T]).$(1.85)
$\frac{{\partial {{U}_{2}}(x,t)}}{{\partial t}} \in \mathbb{C}_{b}^{{(2 + 1)}}({{\mathbb{R}}^{3}} \times [0,T]),$(1.86)
$\frac{{\partial {{U}_{2}}(x,t)}}{{\partial t}} \in {{\mathbb{C}}^{{2 + \alpha }}}({{\mathbb{R}}^{3}})\quad {\text{для}}\;{\text{всех}}\quad t \in [0,T].$(1.87)
$\frac{{{{\partial }^{2}}U(x,{{t}_{2}})}}{{\partial {{t}^{2}}}} - \frac{{{{\partial }^{2}}U(x,{{t}_{1}})}}{{\partial {{t}^{2}}}} = W(x,{{t}_{2}}) - W(x,{{t}_{1}}) + \int\limits_{{{t}_{1}}}^{{{t}_{2}}} \frac{{\partial {{U}_{2}}(x,t)}}{{\partial t}}{\kern 1pt} dt,$(1.88)
$\begin{gathered} {{\left| {\frac{{{{\partial }^{2}}U(x,{{t}_{2}})}}{{\partial {{t}^{2}}}} - \frac{{{{\partial }^{2}}U(x,{{t}_{1}})}}{{\partial {{t}^{2}}}}} \right|}_{{2 + \alpha }}}\;\leqslant \;{{\left| {W(x,{{t}_{2}}) - W(x,{{t}_{1}})} \right|}_{{2 + \alpha }}} + \int\limits_{{{t}_{1}}}^{{{t}_{2}}} {{\left| {\frac{{\partial {{U}_{2}}(x,t)}}{{\partial t}}} \right|}_{{2 + \alpha }}}{\kern 1pt} dt, \\ \mathop {\sup }\limits_{t \in [0,T]} {{\left| {\frac{{\partial {{U}_{2}}(x,t)}}{{\partial t}}} \right|}_{{2 + \alpha }}}\;\leqslant \;{{b}_{3}}(T)\mathop {\sup }\limits_{t \in [0,T]} {{\left| {\rho (x,t)} \right|}_{\alpha }}. \\ \end{gathered} $Теорема доказана полностью.
Справедлива следующая
Теорема 2. Если $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$, то для любого $k \in \mathbb{N} \cup \{ 0\} $ имеем
Доказательство. Утверждение фактически доказано при доказательстве теоремы 1.
Введем следующие потенциалы:
(1.89)
${{U}_{0}}(x,t) = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} \mathcal{E}(x - y,t - \tau ){{\rho }_{0}}(y,\tau ){\kern 1pt} dy{\kern 1pt} d\tau ,$(1.90)
${{V}_{{01}}}(x,t) = \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial t}}{{\mu }_{1}}(y){\kern 1pt} dy,$(1.91)
${{\rho }_{0}}(x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}((1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{\gamma /2}}};{{\mathbb{R}}^{3}}),$(1.92)
$\begin{gathered} {{\mu }_{0}}(x) \in {{\mathbb{C}}^{\alpha }}((1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{2}}/2}}};{{\mathbb{R}}^{3}}), \\ {{\mu }_{0}}(x) \in {{\mathbb{C}}^{\alpha }}((1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{3}}/2}}};{{\mathbb{R}}^{3}}) \\ \end{gathered} $(1.93)
${{U}_{0}}(x,t) = \frac{{U(x,t)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}},\quad \rho (x,t) = (1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{\gamma /2}}}{{\rho }_{0}}(x,t),$(1.94)
${{V}_{{01}}}(x,t) = \frac{{{{V}_{1}}(x,t)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}}},\quad \mu (x) = (1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{3}}/2}}}{{\mu }_{1}}(x).$Теорема 3. Если выполнены соотношения (1.91),(1.92), то при $\alpha \in (0,1)$ и $\min \{ \gamma ,{{\beta }_{2}},{{\beta }_{3}}\} \; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$ справедливы соотношения
Доказательство. Теорема является следствием равенств (1.93), (1.94) и теорем 1, 2.
Справедлива следующая
Лемма 1.2. Если ${{u}_{0}}(x),\;{{u}_{1}}(x) \in \mathbb{C}_{b}^{{(2)}}({{\mathbb{R}}^{3}}),$ то справедливы следующие равенства:
(1.95)
$\frac{{\partial {{V}_{{00}}}[\Delta {{u}_{1}} - {{u}_{1}}]}}{{\partial t}}(x,0) = - \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\left[ {\Delta {{u}_{1}}(y) - {{u}_{1}}(y)} \right]{\kern 1pt} dy = {{u}_{1}}(x),$(1.96)
${{V}_{{01}}}[\Delta {{u}_{0}} - {{u}_{0}}](x,0) = - \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\exp ( - {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{4\pi {\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}\left[ {\Delta {{u}_{0}}(y) - {{u}_{0}}(y)} \right]{\kern 1pt} dy = {{u}_{0}}(x),$(1.97)
$\begin{gathered} {{U}_{{00}}}(x,0) = \frac{{\partial {{U}_{{00}}}}}{{\partial t}}(x,0) = 0, \\ {{V}_{{00}}}(x,0) = 0,\quad \frac{{\partial {{V}_{{01}}}}}{{\partial t}}(x,0) = 0\quad {\text{для}}\;{\text{каждого}}\quad x \in {{\mathbb{R}}^{3}}. \\ \end{gathered} $Доказательство. Равенства (1.95) и (1.96) являются следствиями теоремы 2 и доказаны, например, в работе [3]. Равенства (1.97) являются следствиями леммы I.5.1.
Наконец, справедлива следующая
Теорема 4. Если ${{\rho }_{0}}(x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})),$ ${{\mu }_{0}}(x),{\kern 1pt} {{\mu }_{1}}(x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1),$ то
(1.99)
$\begin{gathered} {{\mathfrak{M}}_{{x,t}}}[{{V}_{{00}}}](x,t) = {{\mathfrak{M}}_{{x,t}}}[{{V}_{{01}}}](x,t) = 0\quad {\text{для}}\;{\text{всех}}\quad (x,t) \in {{\mathbb{R}}^{3}} \times [0,T], \\ {{\mathfrak{M}}_{{x,t}}}[w](x,t) = {{\Delta }_{x}}\frac{{{{\partial }^{2}}w(x,t)}}{{\partial {{t}^{2}}}} + \sum\limits_{j = 1}^3 \,\omega _{j}^{2}\frac{{{{\partial }^{2}}w(x,t)}}{{\partial x_{j}^{2}}}. \\ \end{gathered} $Доказательство. Пусть $\langle \langle \cdot , \cdot \rangle \rangle $ – скобки двойственности между пространством основных функций $\mathcal{D}({{\mathbb{R}}^{3}} \times (0,T))$ и пространством обобщенных функций $\mathcal{D}{\kern 1pt} '({{\mathbb{R}}^{3}} \times (0,T))$, а $\langle \cdot , \cdot \rangle $ – скобки двойственности между пространством основных функций $\mathcal{D}({{\mathbb{R}}^{3}})$ и пространством обобщенных функций $\mathcal{D}{\kern 1pt} '({{\mathbb{R}}^{3}})$. Тогда справедливы следующие равенства:
(1.100)
$\begin{gathered} \left\langle {\left\langle {{{\mathfrak{M}}_{{x,t}}}[{{U}_{0}}](x,t),\phi (x,t)} \right\rangle } \right\rangle \left\langle {\left\langle {{{\mathfrak{M}}_{{x,t}}}[\mathcal{E}](x,t) * {{\rho }_{0}}(x,t),\phi (x,t)} \right\rangle } \right\rangle = \\ \, = \left\langle {\left\langle {\delta (x,t) * {{\rho }_{0}}(x,t),\phi (x,t)} \right\rangle } \right\rangle \left\langle {\left\langle {{{\rho }_{0}}(x,t),\phi (x,t)} \right\rangle } \right\rangle , \\ \end{gathered} $(1.101)
$\begin{gathered} \left\langle {\left\langle {{{\mathfrak{M}}_{{x,t}}}[{{V}_{{01}}}](x,t),\phi (x,t)} \right\rangle } \right\rangle = \left\langle {\left\langle {{{\mathfrak{M}}_{{x,t}}}[\mathcal{E}](x,t) * \delta {\kern 1pt} '(t){{\mu }_{1}}(x),\phi (x,t)} \right\rangle } \right\rangle = \\ = \left\langle {\left\langle {\delta (x,t) * \delta {\kern 1pt} '(t){{\mu }_{1}}(x),\phi (x,t)} \right\rangle } \right\rangle = \left\langle {\left\langle {\delta {\kern 1pt} '(t){{\mu }_{1}}(x),\phi (x,t)} \right\rangle } \right\rangle = - \left\langle {{{\mu }_{1}}(x),\phi {\kern 1pt} '(x,0)} \right\rangle = 0 \\ \end{gathered} $Пусть
Теорема 5. Если ${{\rho }_{0}}(x,t) \in \mathbb{C}([0,T];{{\mathbb{C}}^{\alpha }}((1 + \;{\text{|}}x{{{\text{|}}}^{2}}{{)}^{{\gamma /2}}};{{\mathbb{R}}^{3}})),$ при $\alpha \in (0,1)$ и
(1.102)
${{\Delta }_{x}}{{u}_{0}}(x) - {{u}_{0}}(x) \in {{\mathbb{C}}^{\alpha }}((1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{2}}/2}}};{{\mathbb{R}}^{3}}),$(1.103)
${{\Delta }_{x}}{{u}_{1}}(x) - {{u}_{1}}(x) \in {{\mathbb{C}}^{\alpha }}((1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{3}}/2}}};{{\mathbb{R}}^{3}})$Доказательство. Доказательство основано на теоремах 2, 4 и лемме 1.2.
Замечание 1. Заметим, что мы имеем следующие достаточные условия на функции ${{u}_{0}}(x)$ и ${{u}_{1}}(x)$ такие, чтобы были выполнены соотношения (1.102), (1.103):
2. АПРИОРНАЯ ОЦЕНКА ТИПА ШАУДЕРА
Если $u(x,t) \in \mathbb{C}_{b}^{{(2 + 2)}}({{\mathbb{R}}^{3}} \times [0,T]),$ то справедлива следующая третья формула Грина (см. формулу (9.1) теоремы 3 статьи [1]):
(2.1)
$\begin{gathered} u(x,t) = \int\limits_0^t {\kern 1pt} \int\limits_{{{\mathbb{R}}^{3}}} {\kern 1pt} \mathcal{E}(x - \xi ,t - \tau ){{\mathfrak{M}}_{{\xi ,\tau }}}[u](\xi ,\tau ){\kern 1pt} d\xi {\kern 1pt} d\tau + \\ + \;\int\limits_{{{\mathbb{R}}^{3}}} \left[ {\mathcal{E}(x - \xi ,t)[{{\Delta }_{\xi }}{{u}_{1}}(\xi ) - {{u}_{1}}(\xi )] + \frac{{\partial{ \mathcal{E}}(x - \xi ,t)}}{{\partial t}}[{{\Delta }_{\xi }}{{u}_{0}}(\xi ) - {{u}_{0}}(\xi )]} \right]{\kern 1pt} d\xi . \\ \end{gathered} $3. ОЦЕНКИ ТИПА ШАУДЕРА ДЛЯ ПОТЕНЦИАЛОВ С ВЕСОМ
В этом разделе мы воспользуемся методами исследований из работы [2] (см. также работу [4]). Рассмотрим следующий потенциал с весом:
(3.1)
$ + \;{{\beta }_{1}}{{x}_{i}}{{(1 + \;{\text{|}}x{{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial {{x}_{j}}}}f(y){\kern 1pt} dy + {{\beta }_{1}}{{x}_{j}}{{(1 + \;{\text{|}}x{{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial {{x}_{i}}}}f(y){\kern 1pt} dy + $Прежде всего нам нужно получить вспомогательные оценки. Справедливы равенства
(3.2)
$\begin{gathered} {{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}F({{x}_{1}} - y,t) - {{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}F({{x}_{2}} - y,t) = \int\limits_0^1 \frac{\partial }{{\partial s}}\left[ {{{{(1 + \;{\text{|}}{{x}_{s}}{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}F({{x}_{s}} - y,t)} \right]{\kern 1pt} ds = \\ \, = \{ {{x}_{s}} = s{{x}_{1}} + (1 - s){{x}_{2}}\} = \int\limits_0^1 {\kern 1pt} {\kern 1pt} \sum\limits_{j = 1}^3 \,{{\beta }_{1}}{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2 - 1}}}{{x}_{{sj}}}({{x}_{{1j}}} - {{x}_{{2j}}})F({{x}_{s}} - y,t){\kern 1pt} ds + \\ \, + \int\limits_0^1 \,{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\sum\limits_{j = 1}^3 \frac{{\partial F({{x}_{s}} - y,t)}}{{\partial {{x}_{{sj}}}}}({{x}_{{1j}}} - {{x}_{{2j}}}) = {{K}_{1}} + {{K}_{2}}. \\ \end{gathered} $(3.3)
${{(1 + \;{\text{|}}{{x}_{s}}{\kern 1pt} {{{\text{|}}}^{2}})}^{{1/2}}}\;\leqslant \;\sqrt 2 {{(1 + \;{\text{|}}{{x}_{s}} - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{1/2}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{1/2}}}.$(3.4)
${\text{|}}{{K}_{1}}{\text{|}}\;\leqslant \;3{{\beta }_{1}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} \int\limits_0^1 \left| {F({{x}_{s}} - y,t){\kern 1pt} } \right|{\kern 1pt} ds,\quad {{\beta }_{1}} \in [0,1].$(3.5)
${\text{|}}{{K}_{2}}{\text{|}}\;\leqslant \;{{2}^{{{{\beta }_{1}}/2}}}3(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} \int\limits_0^1 \,{{(1 + \;{\text{|}}{{x}_{s}} - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\left| {{{D}_{x}}F({{x}_{s}} - y,t){\kern 1pt} } \right|{\kern 1pt} ds.$(3.6)
$ \times \;\left\{ \begin{gathered} {{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}{{x}_{s}} - y{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}},\quad {\text{если}}\quad {{\beta }_{1}} > 1; \hfill \\ 1,\quad {\text{если}}\quad {{\beta }_{1}} \in [0,1]; \hfill \\ \end{gathered} \right. + $Заметим, что имеет место
Теорема 6. Если $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1),$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$, то
Доказательство.
Шаг 1: Пусть ${{x}_{1}},{{x}_{2}} \in {{\mathbb{R}}^{3}}$ такие точки, что
(3.7)
$\begin{gathered} {{u}_{4}}(x,t) = \int\limits_{{{\mathbb{R}}^{3}}\backslash O({{x}_{0}},2{{R}_{0}})} {{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}f(y){\kern 1pt} dy + \\ \, + \int\limits_{O({{x}_{0}},2{{R}_{0}})} {{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}\left[ {f(y) - f(x)} \right]{\kern 1pt} dy + \\ + \;{{(1 + \;{\text{|}}x{{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}f(x)\int\limits_{\partial O({{x}_{0}},2{{R}_{0}})} \frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial {{y}_{j}}}}\cos ({{n}_{y}},{{e}_{i}}){\kern 1pt} d{{S}_{y}},\quad x \in O({{x}_{0}},2{{R}_{0}}). \\ \end{gathered} $(3.8)
${{F}_{2}}(x,y,t): = (1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}\frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}.$(3.9)
${{u}_{4}}({{x}_{1}},t) - {{u}_{4}}({{x}_{2}},t) = {{I}_{0}} + {{I}_{1}} + {{I}_{2}} + {{I}_{3}} + {{I}_{4}} + {{I}_{5}} + {{I}_{6}},$(3.10)
${{I}_{0}}: = \int\limits_{{{\mathbb{R}}^{3}}\backslash O({{x}_{0}},2{{R}_{0}})} \left[ {{{F}_{2}}({{x}_{1}},y,t) - {{F}_{2}}({{x}_{2}},y,t)} \right]f(y){\kern 1pt} dy,$(3.11)
${{I}_{1}}: = (1 + \;{\text{|}}{{x}_{2}}{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}f({{x}_{2}})\int\limits_{\partial O({{x}_{0}},2{{R}_{0}})} \left[ {\frac{{\partial{ \mathcal{E}}({{x}_{1}} - y,t)}}{{\partial {{y}_{j}}}} - \frac{{\partial{ \mathcal{E}}({{x}_{2}} - y,t)}}{{\partial {{y}_{j}}}}} \right]\cos ({{n}_{y}},{{e}_{i}}){\kern 1pt} d{{S}_{y}},$(3.12)
${{I}_{3}}: = \int\limits_{O({{x}_{0}},\rho )} {{F}_{2}}({{x}_{2}},y,t)(f({{x}_{2}}) - f(y)){\kern 1pt} dy,$(3.13)
${{I}_{4}}: = \int\limits_{O({{x}_{0}},\rho )} {{F}_{2}}({{x}_{1}},y,t)(f(y) - f({{x}_{1}})){\kern 1pt} dy,$(3.14)
${{I}_{5}}: = (f({{x}_{2}}) - f({{x}_{1}}))\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} {{F}_{2}}({{x}_{2}},y,t){\kern 1pt} dy,$(3.15)
${{I}_{6}}: = \int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \left( {{{F}_{2}}({{x}_{2}},y,t) - {{F}_{2}}({{x}_{1}},y,t)} \right)(f({{x}_{1}}) - f(y)){\kern 1pt} dy.$Шаг 2: ${{I}_{0}}$. Заметим, что при ${\text{|}}y - {{x}_{0}}{\text{|}}\; \geqslant \;2{{R}_{0}}$ справедливы неравенства
(3.16)
${\text{|}}{{x}_{s}} - y{\text{|}}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}}\; - \;{\text{|}}{{x}_{s}} - {{x}_{0}}{\text{|}}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}} - \frac{1}{2}{\text{|}}y - {{x}_{0}}{\text{|}} = \frac{1}{2}{\text{|}}y - {{x}_{0}}{\text{|}}\; \geqslant \;{{R}_{0}} > 0,$(3.17)
${\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}\;\leqslant \;{\text{|}}{{x}_{s}} - {{x}_{0}}{\text{|}}\; + \;{\text{|}}y - {{x}_{0}}{\text{|}}\;\leqslant \;\frac{1}{2}{\text{|}}y - {{x}_{0}}{\text{|}}\; + \;{\text{|}}y - {{x}_{0}}{\text{|}} = \frac{3}{2}{\text{|}}y - {{x}_{0}}{\text{|}}.$(3.18)
$\begin{gathered} \leqslant \;{{D}_{1}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} \int\limits_0^1 \frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon )){\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}}}{{{\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}}}{\kern 1pt} ds + \\ + \;{{D}_{2}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\int\limits_0^1 \,{{(1 + \;{\text{|}}{{x}_{s}} - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon )){\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}}}{{{\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}}}{\kern 1pt} ds\;\leqslant \\ \end{gathered} $(3.19)
$\begin{gathered} \left| {{{F}_{2}}({{x}_{1}},y,t) - {{F}_{2}}({{x}_{2}},y,t)} \right|\;\leqslant \;{{D}_{5}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}} \times \\ \times \;{{(1 + \;{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}\frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon )){\text{|}}y - {{x}_{0}}{\text{|}}}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}} + {{D}_{4}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}} \times \\ \, \times {{(1 + \;{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon )){\text{|}}y - {{x}_{0}}{\text{|}}}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}. \\ \end{gathered} $(3.20)
$\begin{gathered} {\text{|}}{{I}_{0}}{\text{|}}\;\leqslant \;{{D}_{3}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{||}}f(x){\kern 1pt} {{{\text{|}}}_{0}}\int\limits_{{{\mathbb{R}}^{3}}\backslash O({{x}_{0}},2{{R}_{0}})} \frac{{\exp ( - (1 - \varepsilon ))(1{\text{/}}2){\text{|}}y - {{x}_{0}}{\text{|}}}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}{\kern 1pt} dy + \\ \, + {{D}_{4}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{\left| {f(x)(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}} \right|}_{0}}\int\limits_{{{\mathbb{R}}^{3}}\backslash O({{x}_{0}},2{{R}_{0}})} {{(1 + \;{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}} \times \\ \times \;\frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon )){\text{|}}y - {{x}_{0}}{\text{|}}}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{6}}(T,{{R}_{0}},\varepsilon ){\text{|}}\mu {{{\text{|}}}_{0}}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} \in [0,1]. \\ \end{gathered} $(3.21)
$\begin{gathered} \times \;\int\limits_{{{\mathbb{R}}^{3}}\backslash O({{x}_{0}},2{{R}_{0}})} {{(1 + \;{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}\frac{{\exp ( - (1 - \varepsilon ))(1{\text{/}}2){\kern 1pt} {\text{|}}y - {{x}_{0}}{\text{|}}}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}{\kern 1pt} dy + \\ \, + {{D}_{4}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{\left| {f(x)(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}} \right|}_{0}} \times \\ \end{gathered} $(3.22)
${\text{|}}{{I}_{0}}{\text{|}}\;\leqslant \;{{D}_{8}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}.$Шаг 3: ${{I}_{1}}$. Справедливо следующее равенство:
(3.23)
$\leqslant \;{{D}_{9}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} \int\limits_0^1 \frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon ){\kern 1pt} {\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}{\kern 1pt} )}}{{{\text{|}}{{x}_{s}} - y{\kern 1pt} {\text{|}}}}{\kern 1pt} ds\;\leqslant $(3.24)
$\begin{gathered} {\text{|}}{{I}_{1}}{\text{|}}\;\leqslant \;{{\left| {{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(x)} \right|}_{0}}{{D}_{{10}}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}} \times \\ \, \times \int\limits_{\partial O({{x}_{0}},2{{R}_{0}})} \frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon ){\kern 1pt} {\text{|}}y - {{x}_{0}}{\text{|}})}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}{\kern 1pt} d{{S}_{y}}\;\leqslant \;{{D}_{{11}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}. \\ \end{gathered} $Шаг 4: ${{I}_{2}}.$ Справедлива следующая цепочка неравенств:
(3.25)
$\begin{gathered} {\text{|}}{{I}_{2}}{\text{|}}\;\leqslant \;{{D}_{{12}}}(T,{{R}_{0}},\varepsilon ){{\left[ {{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(x)} \right]}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}\int\limits_{\partial O({{x}_{0}},2{{R}_{0}})} \frac{{\exp ( - (1{\text{/}}2)(1 - \varepsilon ){\kern 1pt} {\text{|}}y - {{x}_{0}}{\text{|}}{\kern 1pt} )}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}{\kern 1pt} d{{S}_{y}}\;\leqslant \\ \leqslant \;{{D}_{{13}}}(T,{{R}_{0}},\varepsilon ){{\left[ {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right]}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}\;\leqslant \;{{D}_{{14}}}(T,{{R}_{0}},\varepsilon ){\text{|}}\mu {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}, \\ \end{gathered} $Шаг 5: ${{I}_{3}}$ и ${{I}_{4}}$. Получим оценку на интеграл ${{I}_{3}},$ поскольку оценка для интеграла ${{I}_{4}}$ получается заменой ${{x}_{2}} \leftrightarrow {{x}_{1}}.$ Выражение (3.12) для интеграла ${{I}_{3}}$ можно переписать в следующем виде:
(3.26)
${\text{|}}y - {{x}_{2}}{\text{|}}\;\leqslant \;{\text{|}}y - {{x}_{0}}{\text{|}}\; + \;{\text{|}}{{x}_{2}} - {{x}_{0}}{\text{|}}\;\leqslant \;\rho + \frac{\rho }{2} = \frac{{3\rho }}{2}.$(3.27)
${\text{|}}{{I}_{{31}}}{\text{|}}\;\leqslant \;{{D}_{{15}}}(T,{{R}_{0}},\varepsilon ){{\left[ {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right]}_{\alpha }}\int\limits_{O({{x}_{2}},3\rho /2)} \frac{1}{{{\text{|}}y - {{x}_{2}}{{{\text{|}}}^{{3 - \alpha }}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{16}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}.$(3.28)
$\left| {{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{\text{|}}y - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} \in [0,1],$(3.29)
$\begin{gathered} \left| {{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\text{|}}y - {{x}_{2}}{\text{|}}{\kern 1pt} \int\limits_0^1 \,{{(1 + \;{\text{|}}{{x}_{s}} - y{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} ds\;\leqslant \\ \leqslant \;3{{\beta }_{1}}{{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}y - {{x}_{2}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} {\text{|}}y - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} > 1, \\ \end{gathered} $(3.30)
${\text{|}}{{I}_{{32}}}{\text{|}}\;\leqslant \;{{D}_{{17}}}(T,{{R}_{0}},\varepsilon ){\text{|}}f{{{\text{|}}}_{0}}\int\limits_{O({{x}_{2}},3\rho /2)} \frac{1}{{{\text{|}}y - {{x}_{2}}{\text{|}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{18}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{{0{\kern 1pt} }}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} \in [0,1].$(3.31)
$\begin{gathered} {\text{|}}{{I}_{{32}}}{\text{|}}\;\leqslant \;{{D}_{{19}}}(T,{{R}_{0}},\varepsilon ){{\left| {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{(1 + {{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right|}_{0}} \times \\ \times \;\int\limits_{O({{x}_{2}},3\rho /2)} \frac{{{{{(1 + \;{\text{|}}y - {{x}_{2}}{{{\text{|}}}^{2}})}}^{{({{\beta }_{1}} - 1)/2}}}}}{{{\text{|}}y - {{x}_{2}}{{{\text{|}}}^{2}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{20}}}(T,{{R}_{0}},\varepsilon ){\text{|}}\mu {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} > 1. \\ \end{gathered} $(3.32)
${\text{|}}{{I}_{3}}{\text{|}}\;\leqslant \;{{D}_{{21}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}.$(3.33)
${\text{|}}{{I}_{4}}{\text{|}}\;\leqslant \;{{D}_{{21}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}.$Шаг 6: ${{I}_{5}}.$ Выражение (3.14) можно переписать в следующем виде:
(3.34)
$\begin{gathered} {{I}_{5}} = \left[ {{{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f({{x}_{2}}) - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f({{x}_{1}})} \right]\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}{\kern 1pt} dy + \\ \, + \left[ {{{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right]f({{x}_{1}})\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}{\kern 1pt} dy:{{I}_{{51}}} + {{I}_{{52}}}. \\ \end{gathered} $(3.35)
$J = \int\limits_{\partial O({{x}_{0}},2{{R}_{0}})} \frac{{\partial{ \mathcal{E}}({{x}_{2}} - y,t)}}{{\partial {{y}_{j}}}}\cos ({{n}_{y}},{{e}_{i}}){\kern 1pt} dy - \int\limits_{\partial O({{x}_{0}},\rho )} \frac{{\partial{ \mathcal{E}}({{x}_{2}} - y,t)}}{{\partial {{y}_{j}}}}\cos ({{n}_{y}},{{e}_{i}}){\kern 1pt} dy: = {{J}_{1}} + {{J}_{2}}.$(3.36)
${\text{|}}y - {{x}_{2}}{\text{|}}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}}\; - \;{\text{|}}{{x}_{2}} - {{x}_{0}}{\text{|}}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}} - \frac{\rho }{2}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}} - \frac{1}{4}{\text{|}}y - {{x}_{0}}{\text{|}} = \frac{3}{4}{\text{|}}y - {{x}_{0}}{\text{|}}.$(3.37)
${\text{|}}{{J}_{1}}{\text{|}}\;\leqslant \;{{D}_{{22}}}(T,{{R}_{0}},\varepsilon )\int\limits_{\partial O({{x}_{0}},2{{R}_{0}})} \frac{{\exp ( - (1 - \varepsilon )(3{\text{/}}4){\kern 1pt} {\text{|}}y - {{x}_{0}}{\text{|}}{\kern 1pt} )}}{{{\text{|}}y - {{x}_{0}}{\text{|}}}}{\kern 1pt} d{{S}_{y}}\;\leqslant \;{{D}_{{23}}}(T,{{R}_{0}},\varepsilon ) < + \infty .$(3.38)
${\text{|}}{{J}_{2}}{\text{|}}\;\leqslant \;{{D}_{{24}}}(T,{{R}_{0}},\varepsilon )\int\limits_{\partial O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{2}}{{{\text{|}}}^{2}}}}{\kern 1pt} d{{S}_{y}}\;\leqslant \;{{D}_{{25}}}(T,{{R}_{0}},\varepsilon )\int\limits_{\partial O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{2}}}}{\kern 1pt} d{{S}_{y}} = {{D}_{{26}}}(T,{{R}_{0}},\varepsilon ) < + \infty .$(3.39)
${\text{|}}J{\kern 1pt} {\text{|}}\;\leqslant \;{{D}_{{27}}}(T,{{R}_{0}},\varepsilon ) < + \infty .$(3.40)
${\text{|}}{{I}_{{51}}}{\text{|}}\;\leqslant \;{{D}_{{27}}}(T,{{R}_{0}},\varepsilon ){{\left[ {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right]}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}\;\leqslant \;{{D}_{{28}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}.$(3.41)
$\left| {{{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} \in [0,1],$(3.42)
$\begin{gathered} \left| {{{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} \int\limits_0^1 \,{{(1\; + \;{\text{|}}{{x}_{s}} - {{x}_{1}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} ds\;\leqslant \\ \leqslant \;3{{\beta }_{1}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}},\quad {{\beta }_{1}} > 1. \\ \end{gathered} $(3.43)
${\text{|}}{{I}_{{52}}}{\text{|}}\;\leqslant \;{{D}_{{29}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}f(x){{{\text{|}}}_{0}}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}\;\leqslant \;{{D}_{{30}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu (x){\kern 1pt} {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} \in [0,1].$(3.44)
${\text{|}}{{I}_{{52}}}{\text{|}}\;\leqslant \;{{D}_{{31}}}(T,{{R}_{0}},\varepsilon ){{\left| {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{(1 + {{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right|}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}\;\leqslant \;{{D}_{{32}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} > 1.$(3.45)
${\text{|}}{{I}_{5}}{\text{|}}\;\leqslant \;{{D}_{{33}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}.$Шаг 7: ${{I}_{6}}.$ Интеграл ${{I}_{6}},$ определенный равенством (3.15), можно представить в следующем виде:
(3.47)
${{I}_{{62}}}: = \int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \left[ {\frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}} - \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{1}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}} \right]\left[ {{{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f({{x}_{1}}) - {{{(1 + \;{\text{|}}y{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(y)} \right]{\kern 1pt} dy,$(3.48)
${{I}_{{63}}}: = \int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \left[ {\frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}} - \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{1}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}} \right]\left[ {{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right]f(y){\kern 1pt} dy.$(3.49)
${\text{|}}{{x}_{1}} - y{\text{|}}\;\leqslant \;{\text{|}}y - {{x}_{0}}{\text{|}}\; + \;{\text{|}}{{x}_{1}} - {{x}_{0}}{\text{|}}\;\leqslant \;{\text{|}}y - {{x}_{0}}{\text{|}} + \frac{\rho }{2}\;\leqslant \;\frac{3}{2}{\text{|}}y - {{x}_{0}}{\text{|}},$(3.50)
${\text{|}}{{x}_{2}} - y{\text{|}}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}}\; - \;{\text{|}}{{x}_{2}} - {{x}_{0}}{\text{|}}\; \geqslant \;{\text{|}}y - {{x}_{0}}{\text{|}} - \frac{\rho }{2}\; \geqslant \;\frac{1}{2}{\text{|}}y - {{x}_{0}}{\text{|}}.$(3.51)
$\begin{gathered} {\text{|}}{{I}_{{61}}}{\text{|}}\;\leqslant \;{{D}_{{34}}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{2}} - {{x}_{1}}{\text{|}}{\kern 1pt} {\kern 1pt} {{[f(x)]}_{\alpha }}\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{\text{|}}{{x}_{1}} - y{{{\text{|}}}^{\alpha }}}}{{{\text{|}}{{x}_{2}} - y{{{\text{|}}}^{3}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{35}}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{2}} - {{x}_{1}}{\text{|}}{\kern 1pt} {\kern 1pt} {{[f(x)]}_{\alpha }} \times \\ \, \times \int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{{3 - \alpha }}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{36}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu (x){\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}},\quad {{\beta }_{1}} \in [0,1]. \\ \end{gathered} $(3.52)
$\begin{gathered} {{I}_{{61}}}:\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}\left[ {{{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right]f({{x}_{1}}){\kern 1pt} dy - \\ - \;\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}\left[ {{{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right]f(y){\kern 1pt} dy: = {{I}_{{611}}} + {{I}_{{612}}}. \\ \end{gathered} $(3.53)
$\begin{gathered} \left| {{{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{{2}^{{({{\beta }_{1}} - 1)/2}}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{\left( {1 + \;{\text{|}}{{x}_{2}} - {{x}_{1}}{{{\text{|}}}^{2}}} \right)}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}\;\leqslant \\ \leqslant \;3{{\beta }_{1}}{{2}^{{{{\beta }_{1}} - 1}}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}. \\ \end{gathered} $(3.54)
$\begin{gathered} {\text{|}}{{I}_{{611}}}{\text{|}}\;\leqslant \;{{D}_{{37}}}(T,{{R}_{0}},\varepsilon ){{\left| {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{(1 + {{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right|}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}} \times \\ \times \;\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{3}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{37}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {\kern 1pt} \text{[}1 + \left| {\ln {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} } \right|{\kern 1pt} ]. \\ \end{gathered} $(3.55)
$\begin{gathered} \left| {{{{(1 + \;{\text{|}}{{x}_{2}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{{2}^{{({{\beta }_{1}} - 1)/2}}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} \int\limits_0^1 \,{{(1 + \;{\text{|}}{{x}_{s}} - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} ds\;\leqslant \\ \leqslant \;3{{\beta }_{1}}{{2}^{{{{\beta }_{1}} - 1}}}{{(1 + {{(1{\text{/}}2 + 2{{R}_{0}})}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}. \\ \end{gathered} $(3.56)
$\begin{gathered} {\text{|}}{{I}_{{612}}}{\text{|}}\;\leqslant \;{{D}_{{38}}}(T,{{R}_{0}},\varepsilon ){{\left| {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{(1 + {{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right|}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{3}}}}{\kern 1pt} dy\;\leqslant \\ \leqslant \;{{D}_{{39}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {\kern 1pt} \text{[}1 + \left| {\ln {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}} \right|]. \\ \end{gathered} $(3.57)
${\text{|}}{{I}_{{61}}}{\text{|}}\;\leqslant \;{{D}_{{40}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}\left\{ \begin{gathered} 1,\quad {\text{если}}\quad {{\beta }_{1}} \in [0,1]; \hfill \\ 1 + \left| {\ln {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} } \right|,\quad {\text{если}}\quad {{\beta }_{1}} > 1. \hfill \\ \end{gathered} \right.$(3.58)
$\left| {\frac{{{{\partial }^{2}}\mathcal{E}({{x}_{2}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}} - \frac{{{{\partial }^{2}}\mathcal{E}({{x}_{1}} - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}} \right|\;\leqslant \;{{D}_{{41}}}(T,{{R}_{0}},\varepsilon )\frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{4}}}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}.$(3.59)
$\begin{gathered} {\text{|}}{{I}_{{62}}}{\text{|}}\;\leqslant \;{{D}_{{42}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{\left[ {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right]}_{\alpha }}\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{\text{|}}y - {{x}_{1}}{{{\text{|}}}^{\alpha }}}}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{4}}}}{\kern 1pt} dy\;\leqslant \\ \leqslant \;{{D}_{{43}}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{||}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{{4 - \alpha }}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{44}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}, \\ \end{gathered} $(3.60)
$\begin{gathered} {\text{|}}{{I}_{{63}}}{\text{|}}\;\leqslant \;{{D}_{{45}}}(T,{{R}_{0}},\varepsilon ){\text{|}}f{{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{{{\text{|}}y - {{x}_{1}}{\text{|}}}}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{4}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{46}}}(T,{{R}_{0}},\varepsilon ){\text{|}}f{{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}} \times \\ \, \times \int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{3}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{47}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\kern 1pt} {\kern 1pt} \text{[}1 + \left| {\ln {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} } \right|{\kern 1pt} ]. \\ \end{gathered} $(3.61)
$\left| {{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}{{x}_{1}}{{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{{2}^{{({{\beta }_{1}} - 1)/1}}}{{\left( {1 + {{{(1{\text{/}}2 + 2{{R}_{0}})}}^{2}}} \right)}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\text{|}}{{x}_{1}} - y{\kern 1pt} {\text{|}}.$(3.62)
$\begin{gathered} {\text{|}}{{I}_{{63}}}{\text{|}}\;\leqslant \;{{D}_{{48}}}(T,{{R}_{0}},\varepsilon ){\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{{\left| {\frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{{{\text{|}}}^{2}})}}^{{(1 + {{\beta }_{2}} - {{\beta }_{1}})/2}}}}}} \right|}_{0}}\int\limits_{O({{x}_{0}},2{{R}_{0}})\backslash O({{x}_{0}},\rho )} \frac{1}{{{\text{|}}y - {{x}_{0}}{{{\text{|}}}^{3}}}}{\kern 1pt} dy\;\leqslant \\ \leqslant \;{{D}_{{49}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}}{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {\kern 1pt} \text{[}1 + \left| {\ln {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} } \right|{\kern 1pt} ]. \\ \end{gathered} $(3.63)
${\text{|}}{{I}_{6}}{\text{|}}\;\leqslant \;{{D}_{{50}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}\left( {{\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} {\kern 1pt} [1 + \left| {\ln {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}{\kern 1pt} } \right|{\kern 1pt} ]\; + \;{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}} \right).$(3.64)
$\left| {{{u}_{4}}({{x}_{1}},t) - {{u}_{4}}({{x}_{2}},t)} \right|\;\leqslant \;{{D}_{{51}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }},\quad \alpha \in (0,1),$Шаг 8: ${\text{|}}{{u}_{4}}{{{\text{|}}}_{0}}$. Теперь наша задача оценить – ${\text{|}}{{u}_{4}}{{{\text{|}}}_{0}}$. В силу равенства (4.8) справедливо следующее выражение для произвольного $\delta > 0$:
(3.65)
$\begin{gathered} \, + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,\delta )} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}f(y){\kern 1pt} dy + \\ + \;\int\limits_{O(x,\delta )} \frac{{{{\partial }^{2}}}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}\mathcal{E}(x - y,t)\left[ {{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(y) - {{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(x)} \right]{\kern 1pt} dy + \\ \end{gathered} $(3.66)
$\left| {{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{\text{|}}x - y{\text{|}}.$(3.67)
$\left| {{\kern 1pt} {{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}} \right|\;\leqslant \;3{{\beta }_{1}}{\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} {{2}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}.$(3.68)
$\begin{gathered} \left| {{{J}_{2}}} \right| = \left| {\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{j}}\partial {{y}_{i}}}}[(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}} - {{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}]f(y){\kern 1pt} dy} \right|\;\leqslant \;\int\limits_{O(x,{{R}_{0}})} \frac{{{{D}_{{52}}}(T,{{R}_{0}},\varepsilon )}}{{{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}}}}{\text{|}}f(y){\kern 1pt} {\text{|}}{\kern 1pt} dy + \\ \, + {{D}_{{53}}}(T,{{R}_{0}},\varepsilon )\int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{0}})} \exp ( - (1 - \varepsilon ){\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}{\kern 1pt} )\,|\,{\text{|}}f(y){\text{|}}{\kern 1pt} dy\;\leqslant \;{{D}_{{54}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}},\quad {{\beta }_{1}} \in [0,1], \\ \end{gathered} $(3.69)
$\begin{gathered} \leqslant \;{{D}_{{55}}}(T,{{R}_{0}},\varepsilon )\int\limits_{O(x,{{R}_{0}})} \frac{{{{{(1\; + \;{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{1}} - 1)/2}}}}}{{{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{({{\beta }_{1}} - 1)/2}}}{\kern 1pt} {\text{|}}f(y){\kern 1pt} {\text{|}}{\kern 1pt} dy + \\ + \;{{D}_{{56}}}(T,{{R}_{0}},\varepsilon )\int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{0}})} \exp ( - (1 - \varepsilon ){\kern 1pt} {\text{|}}x - y{\text{|}}{\kern 1pt} )(1 + \;{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{({{\beta }_{1}} - 1)/2}}} \times \\ \end{gathered} $Справедливы следующие оценки:
(3.70)
${\text{|}}{{J}_{{11}}}{\text{|}}\;\leqslant \;{{D}_{{58}}}(T,{{R}_{0}},\varepsilon ){\text{|}}\mu {{{\text{|}}}_{0}}\int\limits_{{{\mathbb{R}}^{3}}\backslash O(x,{{R}_{0}})} \frac{1}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{({{\beta }_{2}} - {{\beta }_{1}} + 1)/2}}}}}\frac{{\exp ( - (1 - \varepsilon ){\kern 1pt} {\text{|}}x - y{\kern 1pt} {\text{|}}}}{{{\text{|}}x - y{\kern 1pt} {\text{|}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{59}}}(T,{{R}_{0}},\varepsilon ){\text{|}}\mu {{{\text{|}}}_{0}},$(3.71)
${\text{|}}{{J}_{{12}}}{\text{|}}\;\leqslant \;{{D}_{{60}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}\int\limits_{O(x,{{R}_{0}})} \frac{1}{{{\text{|}}x - y{\kern 1pt} {{{\text{|}}}^{{3 - \alpha }}}}}{\kern 1pt} dy\;\leqslant \;{{D}_{{61}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{0}},\quad {\text{|}}{{J}_{{13}}}{\text{|}}\;\leqslant \;{{D}_{{62}}}(T,{{R}_{0}},\varepsilon ){\text{|}}\mu {{{\text{|}}}_{0}}.$(3.72)
${\text{|}}{{J}_{1}}{\text{|}}\;\leqslant \;{{D}_{{63}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}.$(3.73)
${\text{|}}{{u}_{4}}{{{\text{|}}}_{0}}\;\leqslant \;{{D}_{{64}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }},\quad t \in [0,T].$Шаг 9: Заметим, что если $|{\kern 1pt} {{x}_{1}} - {{x}_{2}}{\kern 1pt} |\; \geqslant \;1,$ то в силу (3.73) справедливы неравенства
(3.74)
$\begin{gathered} {\text{|}}{{u}_{4}}({{x}_{1}},t) - {{u}_{4}}({{x}_{2}},t){\kern 1pt} {{{\text{|}}}_{0}}\;\leqslant \;2{\text{|}}{{u}_{4}}(x,t){{{\text{|}}}_{0}}\;\leqslant \;2{\text{|}}{{u}_{4}}(x,t){\kern 1pt} {{{\text{|}}}_{0}}{\kern 1pt} {\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}\;\leqslant \\ \leqslant \;{{D}_{{65}}}(T,{{R}_{0}},\varepsilon ){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }}{\text{|}}{{x}_{1}} - {{x}_{2}}{{{\text{|}}}^{\alpha }}\quad {\text{при}}\quad {\text{|}}{{x}_{1}} - {{x}_{2}}{\text{|}}\; \geqslant \;1. \\ \end{gathered} $Справедлива следующая
Лемма 3.1. Если $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0,$ то справедливы следующие оценки:
Доказательство. Аналогичное утверждение доказано в [5].
Несложно доказывается следующая
Лемма 3.2. Пусть ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$ и $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1)$. Тогда справедливы следующие оценки:
Из результатов теоремы 6 и лемм 3.1, 3.2 вытекает следующая основная
Теорема 7. Для любой функции $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$ справедлива оценка типа Шаудера
(3.75)
$\begin{gathered} {\text{|}}u(x,t){\kern 1pt} {{{\text{|}}}_{{2 + \alpha }}}\;\leqslant \;d(T){\text{|}}\mu {{{\text{|}}}_{\alpha }},\quad t \in [0,T], \\ u(x,t) = (1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}\int\limits_{{{\mathbb{R}}^{3}}} \mathcal{E}(x - y,t)\frac{{\mu (y)}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy, \\ \end{gathered} $Отметим, что в силу свойств гладкости фундаментального решения $\mathcal{E}(x,t),$ определенного равенством (5.6) [1], справедлива
Теорема 8. Для любой функции $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$ справедлива оценка типа Шаудера
(3.76)
$\begin{gathered} {\text{|}}{{u}_{k}}(x,t){\text{|}}{{{\kern 1pt} }_{{2 + \alpha }}}\;\leqslant \;{{d}_{k}}(T){\kern 1pt} {\text{|}}\mu {\kern 1pt} {{{\text{|}}}_{\alpha }},\quad t \in [0,T],\quad k \in \mathbb{N} \cup \{ 0\} , \\ {{u}_{k}}(x,t) = (1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}}{{)}^{{{{\beta }_{1}}/2}}}\int\limits_{{{\mathbb{R}}^{3}}} \frac{{{{\partial }^{k}}\mathcal{E}(x - y,t)}}{{\partial {{t}^{k}}}}\frac{{\mu (y)}}{{{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}}{\kern 1pt} dy, \\ \end{gathered} $Наконец, рассмотрим следующий потенциал с весом
Теорема 9. Для любой функции $\mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}})$ при $\alpha \in (0,1)$ и ${{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0$ справедлива оценка типа Шаудера
4. ГЛАДКОСТЬ ВЕСОВОГО ПОТЕНЦИАЛА
В этом разделе мы воспользуемся методами исследований из работы [2].
Пусть $\eta (s) \in \mathbb{C}_{b}^{{(1)}}[0, + \infty )$ – функция следующего вида:
причем(4.1)
$\begin{gathered} \, + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(z,R)} \frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}f(y){\kern 1pt} dy + \\ \, + \int\limits_{O(z,R)} \frac{{{{\partial }^{2}}}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}\mathcal{E}(x - y,t)\left[ {{{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(y) - {{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}f(x)} \right]{\kern 1pt} dy + \\ \end{gathered} $(4.2)
$w(x,t): = \int\limits_{{{\mathbb{R}}^{3}}} \mathcal{E}(x - y,t)f(y){\kern 1pt} dy,\quad {v}(x,t): = \frac{{\partial w(x,t)}}{{\partial {{x}_{j}}}} = - \int\limits_{{{\mathbb{R}}^{3}}} \frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial {{y}_{j}}}}f(y){\kern 1pt} dy,$(4.3)
$\begin{gathered} {{v}_{\varepsilon }}(x,t): = - \int\limits_{{{\mathbb{R}}^{3}}} {{\eta }_{\varepsilon }}\frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial {{y}_{j}}}}f(y){\kern 1pt} dy, \\ f(x) = \frac{{\mu (x)}}{{{{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{2}}/2}}}}},\quad {{\beta }_{2}}\; \geqslant \;{{\beta }_{1}}\; \geqslant \;0,\quad \mu (x) \in {{\mathbb{C}}^{\alpha }}({{\mathbb{R}}^{3}}),\quad \alpha \in (0,1]. \\ \end{gathered} $(4.4)
${{K}_{2}}: = \int\limits_{{{\mathbb{R}}^{3}}\backslash O(z,R)} \frac{\partial }{{\partial {{y}_{i}}}}\left( {[1 - {{\eta }_{\varepsilon }}]\frac{{\partial{ \mathcal{E}}(x - y,t)}}{{\partial {{y}_{j}}}}} \right){{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}f(y){\kern 1pt} dy,$(4.6)
$\mathop {\sup }\limits_{x \in \overline {O(0,R)} } \left| {u(x,t) - {{{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}}^{{{{\beta }_{1}}/2}}}\frac{{\partial {{v}_{\varepsilon }}(x,t)}}{{\partial {{x}_{i}}}}} \right| \to + 0\quad {\text{при}}\quad \varepsilon \to + 0$(4.7)
$\mathop {\sup }\limits_{x \in \overline {O(0,R)} } \left| {{{v}_{\varepsilon }}(x,t) - \frac{{\partial w(x,t)}}{{\partial {{x}_{j}}}}} \right| \to + 0\quad {\text{при}}\quad \varepsilon \to + 0$(4.8)
${{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{{{\partial }^{2}}w(x,t)}}{{\partial {{x}_{i}}\partial {{x}_{j}}}} = u(x,t)\quad {\text{для}}\;{\text{всех}}\quad x \in {{\mathbb{R}}^{3}},\quad t \in [0,T],$(4.9)
${{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{{{\partial }^{2}}{{w}_{k}}(x,t)}}{{\partial {{x}_{i}}\partial {{x}_{j}}}} = {{u}_{k}}(x,t)\quad {\text{для}}\;{\text{всех}}\quad x \in {{\mathbb{R}}^{3}},\quad t \in [0,T],$(4.10)
$\, + \int\limits_{{{\mathbb{R}}^{3}}\backslash O(z,R)} \frac{{{{\partial }^{{2 + k}}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}\partial {{t}^{k}}}}{{(1 + \;{\text{|}}y{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}f(y){\kern 1pt} dy + $(4.11)
$\, + \int\limits_{O(z,R)} {{(1 + \;{\text{|}}x{\kern 1pt} {{{\text{|}}}^{2}})}^{{{{\beta }_{1}}/2}}}\frac{{{{\partial }^{2}}\mathcal{E}(x - y,t)}}{{\partial {{y}_{i}}\partial {{y}_{j}}}}\left[ {f(y) - f(x)} \right]{\kern 1pt} dy + $Список литературы
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Гилбарг Д., Трудингер М. Эллиптические дифференциальные уравнения с частными производными второго порядка. М.: Наука, 1989. С. 464.
Корпусов М.О., Яблочкин Д.К. Теория потенциала и оценка Шаудера в гёльдеровских пространствах для $3 + 1$–мерного уравнения Бенджамена–Бона–Махони–Бюргерса // Ж. вычисл. матем. и матем. физ. 2021. Т. 61. № 8. С. 1289–1314.
Ландис E.M. Уравнения второго порядка эллиптического и параболического типов. М.: Наука, 1971. С. 288.
Korpusov M.O., Matveeva A.K. On critical exponents for weak solutions to the Cauchy problem for one nonlinear equation with gradient nonlinearity // MMAS. 2022. V. 46. № 2. P. 1574–1630.
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