Tom Ducat (Warwick)
Constructing 3-fold Divisoral Contractions by Unprojection

Divisoral contractions are an important type of elementary birational map appearing in both the Minimal Model Program and the Sarkisov Program. Unprojection is a way of constructing Gorenstein rings in large codimension by adding new generators and relations to smaller rings. In this talk I will explain how you can use unprojection to explicitly calculate some 3-fold divisoral contractions that contract divisors to curves.