In this paper we develop a new conditional penalty for the fixed charge transportation problem. This penalty is stronger than both the Driebeek penalties and the Lagrangean penalties of Cabot and Erenguc. Computational testing shows that the use of these penalties leads to significant reductions...

In this paper, we present a variant of the vehicle routing problem (VRP) to increase security in the cash-in-transit sector. A speci?c index is used to quantify the exposure of a vehicle to the risk of being robbed along its route. In addition, the problem is subjected to a traditional capacity...

Packing non-identical circles inside a rectangle witnesses a wide range of industrial applications. However, the non-convex constraints in this problem make it intractable using exact analytical approaches. Even via heuristic methods, the solution time for industrial-scale instances sometimes is...

This paper addresses a network pricing problem where users are assigned to the paths of a transportation network according to a mixed logit model, i.e., price sensitivity varies across the user population. For its solution, we propose algorithms based on combinatorial approximations, and show...

Multi-echelon distribution systems and more precisely, optimization of LTL routes related to them is one of the most popular subjects in the last 5 years of vehicle routing research. Although a plethora of models, methods and visions is found, it is still difficult to compare them because they...

In this research, a first order Markov model is built from a corpus of bagana music, a traditional lyre from Ethiopia. Different ways in which low order Markov models can be used to build quality assessment metrics for an optimization algorithm are explained. These are then implemented in a...

The maximum stable set problem is a well-known NP-hard problem in combinatorial optimization, which can be formulated as the maximization of a quadratic square-free polynomial over the (Boolean) hypercube. We investigate a hierarchy of linear programming relaxations for this problem, based on a...

The problem of long-term production planning of open pit mines is a large combinatorial problem. Application of mathematical programming approaches suffer from reduced computational efficiency due to the large amount of decision variables. This paper presents a new metaheuristic approximation...

The stable-set problem is an NP-hard problem that arises in numerous areas such as social networking, electrical engineering, environmental forest planning, bioinformatics clustering and prediction, and computational chemistry. While some relaxations provide high-quality bounds, they result in...

Submodularity (or concavity) is considered as an important property in the field of cooperative game theory. In this article, we characterize submodular minimum coloring games and submodular minimum vertex cover games. These characterizations immediately show that it can be decided in polynomial...