We study the behavior of the signature of colored links [Flo05, CF08] under the splice operation. We extend the construction to colored links in integral homology spheres and show that the signature is almost additive, with a correction term independent of the links. We interpret this correction term as the signature of a generalized Hopf link and give a simple closed formula to compute it.

Abstract. We establish the slice-ribbon conjecture for a family P of Montesinos knots by means of Donaldson's theorem on the intersection forms of definite 4-manifolds. The 4-manifolds that we consider are obtained by plumbing disc bundles over S 2 according to a star-shaped negative-weighted graph with 3 legs such that: i) the central vertex has weight less than or equal to −3; ii) − total weight − 3 #vertices < −1. The Seifert spaces which bound these 4-dimensional plumbing manifolds are the double covers of S 3 branched along the Montesinos knots in the family P.