TITLE: Split Rank of Triangle and Quadrilateral Inequalities
SPEAKER: Dr. Santanu Dey
ABSTRACT:
A simple relaxation of two rows of a simplex tableau is a mixed integer set consisting of two equations with two free integer variables and non-negative continuous variables. Recently Andersen et al. (2007) and Cornuejols and Margot (2008) showed that the facet-defining inequalities of this set are either split cuts or intersection cuts obtained from maximal lattice-free triangles and quadrilaterals. These new families of inequalities can be used to generate valid cutting planes from any two rows of a simplex tableau. Through a result by Cook et al. (1990) (and more recently in a generalization by Li and Richard (2008)) it is known that one particular class of facet-defining triangle inequality does not have a finite split rank, i.e., it cannot be obtained by repeated application of split cuts. In this talk, we show that all other facet-defining triangle and quadrilateral inequalities have a finite split-rank. The proof is constructive, i.e., for a given facet-defining triangle or quadrilateral inequality we present an explicit sequence of split inequalities that can be used to generate it.
