The objective of this paper is to establish new variational principles for symmetric boundary value problems. Let VV be a Banach space and V∗V^* its topological dual. We shall consider problems of the type Λu=DΦ(u)\Lambda u=D \Phi(u) where Λ:V→V∗\Lambda: V \to V^* is a linear operator and Φ:V→R\Phi: V \to \mathbb{R} is a Gâteaux differentiable convex function whose derivative is denoted by DΦD\Phi. It is established that solutions of the latter equation are associated with critical points of functions of the type Iλ,μ(u):=μΦ∗(Λu)−λΦ(u)−μ−λ2⟨Λu,u⟩,I_{\lambda, \mu}(u):= \mu \Phi^* (\Lambda u)-\lambda \Phi(u)- \frac{\mu-\lambda}{2}\langle \Lambda u, u \rangle, where λ,μ\lambda, \mu are two real numbers, Φ∗\Phi^* is the Fenchel dual of the function Φ\Phi and ⟨.,.⟩\langle.,.\rangle is the duality pairing between VV and V∗V^*. By assigning different values to λ\lambda and μ\mu one obtains variety of new and classical variational principles associated to the equation Λu=DΦ(u)\Lambda u=D \Phi(u). Namely, Euler-Lagrange principle (for μ=0\mu=0, λ=1\lambda=1 and symmetric Λ\Lambda), Clarke-Ekeland least action principle (for μ=1\mu=1, λ=0\lambda=0 and symmetric Λ\Lambda), Brezis-Ekeland variational principle (μ=1\mu=1, λ=−1\lambda=-1) and of course many new variational principles such as I1,1(u)=Φ∗(Λu)−Φ(u),I_{1,1}(u)= \Phi^* (\Lambda u)- \Phi(u), which corresponds to λ=1\lambda=1 and μ=1\mu=1. These new potential functions are quite flexible, and can be adapted to easily deal with both nonlinear and homogeneous boundary value problems

Contact details are reproduced from the original publication and may be historical.

Abbas Moameni

School of Mathematics and Statistics, Carleton University, Ottawa, Ont. K1S 5B6, Canada

momeni@math.carleton.ca
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A. Moameni. “New Variational Principles of Symmetric Boundary Value Problems.” Journal of Convex Analysis 24 (2017), No. 2, 365–381. https://doi.org/10.68381/jca24025