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Published online by Cambridge University Press: 21 July 2015
Let   $f$  be an orientation and area preserving diffeomorphism of an oriented surface
 $f$  be an orientation and area preserving diffeomorphism of an oriented surface   $M$  with an isolated degenerate fixed point
 $M$  with an isolated degenerate fixed point   $z_{0}$  with Lefschetz index one. Le Roux conjectured that
 $z_{0}$  with Lefschetz index one. Le Roux conjectured that   $z_{0}$  is accumulated by periodic orbits. In this paper, we will approach Le Roux’s conjecture by proving that if
 $z_{0}$  is accumulated by periodic orbits. In this paper, we will approach Le Roux’s conjecture by proving that if   $f$  is isotopic to the identity by an isotopy fixing
 $f$  is isotopic to the identity by an isotopy fixing   $z_{0}$  and if the area of
 $z_{0}$  and if the area of   $M$  is finite, then
 $M$  is finite, then   $z_{0}$  is accumulated not only by periodic points, but also by periodic orbits in the measure sense. More precisely, the Dirac measure at
 $z_{0}$  is accumulated not only by periodic points, but also by periodic orbits in the measure sense. More precisely, the Dirac measure at   $z_{0}$  is the limit in the weak-star topology of a sequence of invariant probability measures supported on periodic orbits. Our proof is purely topological. It works for homeomorphisms and is related to the notion of local rotation set.
 $z_{0}$  is the limit in the weak-star topology of a sequence of invariant probability measures supported on periodic orbits. Our proof is purely topological. It works for homeomorphisms and is related to the notion of local rotation set.