 , then is a linear combination of the irreducible components of , with coefficients the intersection multiplicities.At the other extreme, if is a non-singular subvariety, the self-intersection formula says that is represented by the top Chern class of the normal bundle of in .To give a definition, in the general case, of the intersection multiplicity was the major concern of André Weil's 1946 book "Foundations of Algebraic Geometry".