Resumen
In 1991 Llibre and MacKay proved that if f is a 2-torus homeomorphism isotopic to identity and the rotation set of f has a non-empty interior then f has positive topological entropy. Here, we give a partial converse theorem. We show that the interior of the rotation set of a 2-torus C1+a diffeomorphism isotopic to identity of positive topological entropy is not empty, under the additional hypothesis that f has a suitable finite covering that is topologically transitive.