Fibers of Polynomial Mappings at Infinity and a Generalized Malgrange Condition

Abstract

Let f be a complex polynomial mapping. We relate the behaviour of f ’at infinity‘ to the characteristic cycle associated to the projective closures of fibres of f. We obtain a condition on the characteristic cycle which is equivalent to a condition on the asymptotic behaviour of some of the minors of the Jacobian matrix of f. This condition generalizes the condition in the hypersurface case known as Malgrange‘s condition. The relation between this condition and the behavior of the characteristic cycle is a partial generalization of Parusinski‘s result in the hypersurface case. We show that the new condition implies the C$^∞$-triviality of f.