Threefold extremal contractions of type (IIA). I
Threefold extremal contractions of type (IIA). I
Let (X, C) be a germ of a threefold X with terminal singularities along an irreducible reduced complete curve C with a contraction f : (X, C) → (Z, o) such that C = f -1 (o) red and -K X is ample.Assume that (X, C) contains a point of …