Let N be a finite set and z be a real-valued function defined on the set of subsets of N that satisfies z(S)+z(T)>-z(SUT)+z(SnT) for all S, T in N. Such a function is called submodular. We considerâ€¦ (More)

The IMA Special Workshop on Mixed-Integer Programming was held in Minneapolis on July 25â€“29, 2005, at the Institute for Mathematics and its Applications. The aim of the conference was to bringâ€¦ (More)

We study several ways of obtaining valid inequalities for mixed integer programs. We show how inequalities obtained from a disjunctive argument can be represented by superadditive functions and weâ€¦ (More)

A separation heuristic for mixed integer programs is presented that theoretically allows one to derive several families of \strong" valid inequalities for speciic models and computationally givesâ€¦ (More)

Constraints arising in practice often contain many 0-1 variables and one or a small number of continuous variables. Existing knapsack separation routines cannot be used on such constraints. Here weâ€¦ (More)