An analytical translation of a criterion of welters and its relation with the K.P. Hierarchy -- Lectures on K3- and enriques surfaces -- Generic invertible sheaves of 2-torsion and generic invertible thetacharacteristics on nodal plane curves -- Fano threefolds with singularities -- Computations of some Hilbert functions related with schubert calculus -- Smoothing algebraic space curves -- Complete intersection curves, the splitting of the normal bundle and the veronese surface -- Compressed algebras and components of the punctual Hilbert scheme -- Theta divisors of generalized Prym varieties I -- Applications of algebraic K-theory to the theory of algebraic cycles -- Double sextics and singular K-3 surfaces -- On the problem of enumerating twisted cubics -- Components of the locus of singular theta divisors of genus 5.