Robin Hartshorne, University of California at Berkeley
 
Gorenstein Liaison of Algebraic Varieties
When the union of two varieties in projective space is a complete intersection, we say they are linked. The equivalence relation generated by successive linkages is called liaison. This relation has been very useful in the classification problem for curves in projective three-space, and more generally for codimension two subschemes of any projective space. In this talk we describe a generalization of this notion, called Gorenstein liaison, which seems to be the appropriate corresponding concept for varieties of codimension at least 3 in projective spaces.