Let F = (f1, …, fm): (Kn, 0) → (Km, 0), where K is either R or C, be an analytic mapping defined in a neighbourhood of the origin. Let Br ⊂ Kn be a closed ball of small radius r centred at the origin. For any regular value y ∈ Km close to the origin, the fibre Wy = F−1(y) ∩ Br is called the Milnor fibre of F. We assume that m [les ] n, because in the other case Wy is void.

Several authors investigated the topology of the Milnor fibres. Let us recall the most important results in the complex case. Let [Oscr ]C,0 denote the ring of germs of analytic functions f: (Cn, 0) → C.