Uncountably many solutions of a systemof third order nonlinear differential equations

Commentationes mathematicae Universitatis Carolinae

Min Liu¹ 

关键词: system of third order nonlinear neutral delay differential equations;    contraction mapping;    completely continuous mapping;    condensing mapping;    uncountably many bounded positive solutions;   

DOI  :  

学科分类：物理化学和理论化学

来源: Univerzita Karlova v Praze * Matematicko-Fyzikalni Fakulta / Charles University in Prague, Faculty of Mathematics and Physics

【 摘 要 】

In this paper, we aim to study the global solvability of the following system of third order nonlinear neutral delay differential equations $$ \aligned & \frac{d}{dt}\Big\{r_i(t)\frac{d}{dt}\Big[\lambda_i(t)\frac{d}{dt} \Big(x_i(t)-f_i(t,x_1(t-\sigma_{i1}),x_2(t-\sigma_{i2}), x_3(t-\sigma_{i3}))\Big)\Big]\Big\} \cr & \qquad \quad + \frac{d}{dt}\Big[r_i(t)\frac{d}{dt}g_i(t,x_1(p_{i1}(t)), x_2(p_{i2}(t)),x_3(p_{i3}(t)))\Big] \cr & \qquad \quad + \frac{d}{dt}h_i(t,x_1(q_{i1}(t)),x_2(q_{i2}(t)), x_3(q_{i3}(t))) \cr & = l_i(t,x_1(\eta_{i1}(t)),x_2(\eta_{i2}(t)),x_3(\eta_{i3}(t))), \quad t\ge t_0,\quad i\in \{1,2,3\} \endaligned $$ in the following bounded closed and convex set $$ \aligned \Omega(a,b)=\Big\{x(t)=\big(x_1(t),x_2(t),x_3(t)\big)\in C([t_0,+\infty),\Bbb{R}^3)a(t)\le x_i(t)\le b(t), \qquad\forall\, t\geq t_0, i\in\{1,2,3\}\Big\}, \qquad \endaligned $$ where $\sigma_{ij}>0$, $r_i,\lambda_i,a,b\in C([t_0,+\infty),\Bbb{R}^{+})$, $f_i,g_i,h_i,l_i\in C([t_0,+\infty)\times\Bbb{R}^3,\Bbb{R})$, \newline $p_{ij},q_{ij},\eta_{ij}\in C([t_0,+\infty),\Bbb{R})$ for $i,j\in\{1,2,3\}$. By applying the Krasnoselskii fixed point theorem, the Schauder fixed point theorem, the Sadovskii fixed point theorem and the Banach contraction principle, four existence results of uncountably many bounded positive solutions of the system are established.

【 授权许可】

CC BY