Session 38. Variational Methods in Nonlinear Analysis

Three critical point theorems with applications to nonlinear BVPs

Marek Galewski, Technical Unviersity of Łódź, Poland
In this talk we are concerned with three critical theorems applicable for \( C^{1}\) action functionals connected to anisotropic problems. Results are based on recent investigations and on ideas developed by Ricerri which can be summarized as follows: Let \((X,\left\Vert .\right\Vert )\) be a uniformly convex Banach space with strictly convex dual, \(J\in C^{1}(X)\) be a functional with compact derivative, \(x_{0},x_{1}\in X,\) \(p,r\in \mathbb{R} \), \(p>1\), \(r>0\). Assume

(A.1) \(\underset{\left\Vert x\right\Vert \rightarrow \infty }{\lim \inf }\frac{J(x)}{\left\Vert x\right\Vert ^{p}}\geq 0;\)

(A.2) \(\underset{x\in X}{\inf }J(x)<\underset{\left\Vert x-x_{0}\right\Vert \leq r}{\inf }J(x);\)

(A.3) \(\left\Vert x_{1}-x_{0}\right\Vert <r\) and \(J(x_{1})<\underset {\left\Vert x-x_{0}\right\Vert =r}{\inf }J(x)\).

There exists a nonempty open set \(A\subseteq (0,+\infty )\) s. t. for all \( \lambda \in A\) the functional \(x\rightarrow \dfrac{\left\Vert x-x_{0}\right\Vert ^{p}}{p}+\lambda J(x)\) has at least three critical points in \(X\). Main idea used in this talk are concerned with the following

  • replace the term \(\left\Vert x\right\Vert ^{p}\) with some convex coercive functional
  • obtain a more precise estimation on the set \(A\)
  • examine applicability of new results
  • generalize to the locally Lipschitz case
  • check what happens when the space is finite dimensional

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