Abstract:
The symplectic versions of the Sturm oscillation and comparison theorem describe some properties of the Maslov index and were proved by developing a suitable intersection theory in the Lagrangian Grassmannian setting. What we propose here is a Sturm oscillation and comparison theorem for indefinite systems, obtained by defining a new index by means of the Brouwer degree of a determinant map associated with a suspension of a complexified family of boundary value problems.
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