In this paper we introduce and study a new problem named min-max edge q-coloring which is motivated by applications in wireless mesh networks. The input of the problem consists of an undirected graph and an integer q. The goal is to color the edges of the graph with as many colors as possible such that: (a) any vertex is incident to at most q different colors, and (b) the maximum size of a colo...

We address the max min vertex cover problem, which is the maximization version of the well studied min independent dominating set problem, known to be NP-hard and highly inapproximable in polynomial time. We present tight approximation results for this problem on general graphs, namely a polynomial approximation algorithm which guarantees an n approximation ratio, while showing that unless P = ...

The present study is focused on the Min-Max Vehicle Routing Problem (MMVRP). According to the characteristics of model, hybrid genetic algorithm is used to get the optimization solution. First of all, use natural number coding so as to simplify the problem; apply improved insertion method so as to improve the feasibility of the solution; retain the best selection so as to guard the diversity of...

this paper discusses the multi-depot vehicle routing problem of heterogeneous fleet of vehicles with time windows for perishable commodities. the objective of the problem is to minimize the total time required for servicing all customers that is equivalent to the total cost. commodities are delivered to the customers with defined time windows by a fleet of heterogeneous vehicles, which have lim...

We consider graph three-partitions with the objective of minimizing the number of edges between the first two partition sets while keeping the size of the third block small. We review most of the existing relaxations for this min-cut problem and focus on a new class of semidefinite relaxations, based on matrices of order 2n+ 1 which provide a good compromise between quality of the bound and com...

A short proof of a difficult theorem of P.D. Seymour on grafts with the max-flow min-cut property is given.

The maximum constraint satisfaction problem (Max CSP) is the following computational problem: an instance is a nite collection of constraints on a set of variables, and the goal is to assign values to the variables that maximises the number of satis ed constraints. Max CSP captures many well-known problems (such as Max k-SAT and Max Cut) and so is NP-hard in general. It is natural to study how ...

In this paper, we consider a special class of wireless networks, called wireless erasure networks. In these networks, each node is connected to a set of nodes by independent erasure channels. The network model incorporates the broadcast nature of the wireless environment in that each node sends out the same signal on its outgoing channels. However, we assume there is no interference in receptio...

Supertree methods are used to construct a large tree over a large set of taxa, from a set of small trees over overlapping subsets of the complete taxa set. Since accurate reconstruction methods are currently limited to a maximum of few dozens of taxa, the use of a supertree method in order to construct the tree of life is inevitable. Supertree methods are broadly divided according to the input ...