Casson - Gordon invariants for boundary links

A link L with components L_1,...,L_n is called a boundary link, if there exist closed oriented pairwise disjoint surfaces S_1,...,S_n such that S_i bounds L_i. Boundary links admit a rich algebraic structure coming from an epimorphism of the fundamental group of S^3-L onto a free group F_n with n generators. In the present paper we use this rich structure to define non-commutative analogs of Casson-Gordon invariants, extending on the works of Cha, Ranicki and Sheiham. This is a joint project with Wojciech Politarczyk.