Results on infinite dimensional topology and applications to the structure of the critical set of nonlinear Sturm-Liouville operators

Dan Burghelea, Nicolau C. Saldanha, Carlos Tomei

We consider the nonlinear Sturm-Liouville differential operator $F(u)=-u^{\prime \prime }+f(u)$ for $u\in H_D^2([0,\pi ])$, a Sobolev space of functions satisfying Dirichlet boundary condition…