Mayer-Vietoris property of the fixed point index

Abstract

In this paper we study a Mayer-Vietoris kind of formula for the fixed point index of maps of ENR triplets f : (X;X1,X2) → (X;X1,X2) having compact fixed point set. We prove it under some suitable conditions. For instance when (X;X1,X2) = (En;En+,En −). We use these results to generalize Poincar´e-Bendixson index formula for vector fields to continuos maps having a sectorial decomposition, to study the fixed point index i(f, 0) of orientation preserving homeomorphisms of E2 + and (E3;E3 +,E3 −) and the fixed point index in the invariant subspace.