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  • Research Article
  • Open Access

A degree theory for a class of perturbed Fredholm maps

Fixed Point Theory and Applications20052005:659461

  • Received: 26 October 2004
  • Published:


We define a notion of degree for a class of perturbations of nonlinear Fredholm maps of index zero between infinite-dimensional real Banach spaces. Our notion extends the degree introduced by Nussbaum for locally -contractive perturbations of the identity, as well as the recent degree for locally compact perturbations of Fredholm maps of index zero defined by the first and third authors.

Authors’ Affiliations

Dipartimento di Matematica Applicata "Giovanni Sansone,", Università degli Studi di Firenze, 3 via S. Marta, Firenze, 50139, Italy
Dipartimento di Matematica "Ulisse Dini,", Università degli Studi di Firenze, 67/A viale G. B. Morgagni, Firenze, 50134, Italy