A family of Halley-Chebyshev iterative schemes for non-Fréchet differentiable operators

A modification of some classical third order methods is studied. The main advantage of these methods is that they do not need evaluate any Fréchet derivative. A convergence theorem in Banach spaces, just assuming that the second divided difference is bounded by a nondecreasing function and a punctual condition, is presented. Fréchet differentiability is not required. Finally, a particular example is analyzed where our conditions are fulfilled and the classical ones fail.