Some remarks on the Lusternik-Schnirelman method for non-differentiable functionals invariant with respect to a finite group action

The principle of symmetric criticality

Richard S. Palais · Communications in Mathematical Physics · 1979 · 1.1K citations

Natural Sciences, Physics, Condensed Matter Physics +10

Variational methods for non-differentiable functionals and their applications to partial differential equations

Kung-Ching Chang · Journal of Mathematical Analysis and Applications · 1981 · 874 citations

Natural Sciences, Mathematics, Differential Equations +13

Periodic solutions of hamiltonian systems

Paul H. Rabinowitz · Communications on Pure and Applied Mathematics · 1978 · 735 citations

Natural Sciences, Mathematics, Physics +13

Generalized cohomological index theories for Lie group actions with an application to bifurcation questions for Hamiltonian systems

Edward Fadell, Paul H. Rabinowitz · Inventiones mathematicae · 1978 · 390 citations

Natural Sciences, Mathematics, Physics +17

Minimax principles for lower semicontinuous functions and applications to nonlinear boundary value problems

Andrzej Szulkin · Annales de l Institut Henri Poincaré C Analyse Non Linéaire · 1986 · 378 citations · Full text

Natural Sciences, Mathematics, Differential Equations +14