Infinite dimensional calculus allowing nonconvex domains with empty interior
Monatshefte für Mathematik , Volume 110 - Issue 2 p. 145- 166
We develop differentiation theory based on a new definition of derivative: in terms of integrals of curves. It applies to a very wide class of domains. Some 'elementary' maps between Fréchet spaces, excluded from calculus by previous theories, now emerge as smooth maps.