This volume is a result of a meeting which took place in June 1986 at 'll Ciocco" in Italy entitled 'Deformation theory of algebras and structures and applicati

The main goal of these notes is the description of a non-linear complex into which the integrability (or compatibility) condition is inserted as a non-linear op

The word ``moduli'' in the sense of this book first appeared in the epoch-making paper of B. Riemann, Theorie der Abel'schen Funktionen, published in 1857. Riem