An approach to Hamiltonian Floer theory for maps from surfaces

In n-dimensional classical field theory one studies maps from n-dimensional manifolds in such a way that classical mechanics is recovered for n=1. In previous papers we have shown that the standard polysymplectic framework in which field theory is described, is not suitable for variational techniques. In this paper, we introduce for n=2 a Lagrange-Hamilton formalism that allows us to define a generalization of Hamiltonian Floer theory. As an application, we prove a cuplength estimate for our Hamiltonian equations that yields a lower bound on the number of solutions to Laplace equations with nonlinearity. We also discuss the relation with holomorphic Floer theory.