Table of Contents

Conics.- Complete conics.- Systems of conics.- Equations of the degeneration hypersurfaces.- Conditions imposed on conics.- Action of the projective group and proper solutions of an enumarative problem.- Genericity of the data of conditions.- Local characters of a condition.- Halphen's first formula.- Computation of characteristic numbers.- Examples.- Strict equivalence of conditions.- Systems of conics contained in Sp,q.- Conics satisfying five independent conditions.- Cycles on W and on B.- Multiplicity cycles and Noether's formula.- Improper intersection numbers.- Generalization of Halphen's formula to conditions of higher order.- Examples of higher order conditions.- Strict equivalence of conditions.- Enumerative ring of W.- Computation of products in hal· (W).- Further examples.