Planar isolated and stable fixed points have index =1

Abstract

Let WCR2 be an open subset and f :W-f ðWÞCR2 be an orientation reversing homeomorphism. We prove that if pAW is an isolated and stable fixed point of f then the fixed point index of f at p; iR2 ð f ; pÞ; is 1. We apply our theorem to the study of the orbital stability of isolated periodic orbits of flows in four-dimensional riemannian manifolds.