Let f be a complex polynomial. We relate the behaviour of f “at infinity” to the sheaf of vanishing cycles of the family $\overline{f}$ of projective closures of fibres of f. We show that the absence of such cycles: (i) is equivalent to a condition on the asymptotic behaviour of gradient of f known as Malgrange’s Condition, (ii) implies the $C^{\infty }$-triviality of f. If the support of sheaf of vanishing cycles of $\overline{f}$ is a finite set, then it detects precisely the change of the topology of the fibres of f. Moreover, in...

To a germ $f:({ℂ}^n,0)\to (ℂ,0)$ with one-dimensional singular locus one associates series of isolated singularities $f_N:=f+l^N$, where l is a general linear function and $N\in$. We prove an attaching result of Iomdin-Lê type which compares the homotopy types of the Milnor fibres of $f_N$ and f. This is a refinement of the Iomdin-Lê theorem in the general setting of a singular underlying space.