Admission control problems have been studied extensively in the past. In a typical setting, resources like bandwidth have to be distributed to the different customers according to their demands maximizing the profit of the company. Yet, in real-world applications those demands are deviating and in order to satisfy their service requirements often a robust approach … Read more
Anderson, Cornuejols and Li (2005) show that for a polyhedral mixed integer set defined by a constraint system Ax >= b, where x is n-dimensional, along with integrality restrictions on some of the variables, any split cut is in fact a split cut for a “basic relaxation”, i.e., one defined by a subset of linearly … Read more
We provide a complete characterization of all polytopes P ⊆ [0,1]^n with empty integer hull whose Gomory-Chvátal rank is n (and, therefore, maximal). In particular, we show that the first Gomory- Chvátal closure of all these polytopes is identical. Article Download View Integer-empty polytopes in the 0/1-cube with maximal Gomory-Chvátal rank
Given an undirected node-weighted graph and a positive integer k, the maximum k-colorable subgraph probem is to select a k-colorable induced subgraph of largest weight. The natural integer programming formulation for this problem exhibits a high degree of symmetry which arises by permuting the color classes. It is well known that such symmetry has negative … Read more
We show that half-integral polytopes obtained as the convex hull of a random set of half-integral points of the 0/1 cube have rank as high as Ω(logn/loglogn) with positive probability — even if the size of the set relative to the total number of half-integral points of the cube tends to 0. The high rank … Read more
The question as to whether the Gomory-Chvatal closure of a non-rational polytope is a polytope has been a longstanding open problem in integer programming. In this paper, we answer this question in the affirmative, by combining ideas from polyhedral theory and the geometry of numbers. Article Download View The Gomory-Chvatal closure of a non-rational polytope … Read more
In this paper we consider a relaxation of the corner polyhedron introduced by Andersen et al., which we denote by RCP. We study the relative strength of the split and triangle cuts of RCP’s. Basu et al. showed examples where the split closure can be arbitrarily worse than the triangle closure under a `worst-cost’ type … Read more
Although well studied, important questions on the rank of the Chvátal-Gomory operator when restricting to polytopes contained in the n-dimensional 0/1 cube have not been answered yet. In particular, the question on the maximal rank of the Chvátal-Gomory procedure for this class of polytopes is still open. So far, the best-known upper bound is O(n^2 … Read more
The cutting plane tree (CPT) algorithm provides a finite disjunctive programming procedure to obtain the solution of general mixed-integer linear programs (MILP) with bounded integer variables. In this paper, we present our computational experience with variants of the CPT algorithm. Because the CPT algorithm is based on discovering multi-term disjunctions, this paper is the first … Read more
We show that every facet-defining inequality of the convex hull of a mixed-integer polyhedral set with two integer variables is a crooked cross cut (which we defined recently in another paper). We then extend this observation to show that crooked cross cuts give the convex hull of mixed-integer sets with more integer variables provided that … Read more