Determining whether there is an integer point in an n-dimensional simplex is an NPcomplete problem. In this paper, a new arbitrary starting variable dimension algorithm is developed for computing an integer point of an n-dimensional simplex. The algorithm is derived from an introduction of an integer labeling rule and an application of a triangulation of the space and is composed of two phases,...

Mixed integer Gomory cuts have become an integral part of state-of-the-art software for solving mixed integer linear programming problems. Therefore, improvements in the performance of these cutting planes can be of great practical value. In this paper we present a simple and fast heuristic for improving the coefficients on the continuous variables in the mixed integer Gomory cuts. This is moti...

We study the complexity of computing the mixed-integer hull conv(P ∩ Z ×R) of a polyhedron P . Given an inequality description, with one integer variable, the mixed-integer hull can have exponentially many vertices and facets in d. For n, d fixed, we give an algorithm to find the mixed integer hull in polynomial time. Given P = conv(V ) and n fixed, we compute a vertex description of the mixed-...

This paper is concerned with the problem of finding the optimal production schedule for an inventory model with time-varying demand and deteriorating items over a finite planning horizon. This problem is formulated as a mixed-integer nonlinear program with one integer variable. The optimal schedule is shown to exist uniquely under some technical conditions. It is also shown that the objective f...

Deciding the existence of an l×m×n integer threeway table with given linesums is NP-complete already for fixed l = 3, but is in P with both l,m fixed. Here we consider huge tables, where the variable dimension n is encoded in binary. Combining recent results on integer cones and Graver bases, we show that if the number of layer types is fixed, then the problem is in P, whereas if it is variable...

We consider mixed-integer sets defined by a linear system Ax ≥ b plus an integrality requirement on one variable, where A is a totally unimodular matrix with at most two nonzero entries per row. We give a complete linear-inequality description for the convex hull of any set of this type.

The Share-a-Ride Problem (SARP) aims at maximizing the profit of serving a set of passengers and parcels using a set of homogeneous vehicles. We propose an adaptive large neighborhood search (ALNS) heuristic to address the SARP. Furthermore, we study the problem of determining the time slack in a SARP schedule. Our proposed solution approach is tested on three sets of realistic instances. The p...

The multivariate integer Chebyshev problem is to find polynomials with integer coefficients that minimize the supremum norm over a compact set in C. We study this problem on general sets, but devote special attention to product sets such as cube and polydisk. We also establish a multivariate analog of the Hilbert-Fekete upper bound for the integer Chebyshev constant, which depends on the dimens...

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