Bl_Z(X) replaces Z ⊂ X by its projectivized normal cone ℙ(N_{Z/X}). Resolves singularities (Hironaka 1964 char 0); fundamental birational operation.
Bl_Z(X) replaces Z ⊂ X by its projectivized normal cone ℙ(N_{Z/X}). Resolves singularities (Hironaka 1964 char 0); fundamental birational operation.