Given a set of rectangular items of different sizes and a rectangular container, the aim of the bi-dimensional Orthogonal Packing Problem (OPP-2 for short) is to decide whether there exists a non-overlapping packing of the items in this container. The rotation of items is not allowed. In this paper we present a new exact algorithm for solving OPP-2, based upon the characterization of solutions ...

Power grid vulnerability is a major concern of our society, and its protection problem is often formulated as a tri-level defender-attacker-defender model. However, this tri-level problem is computationally challenging. In this paper, we design and implement a Column-and-Constraint Generation algorithm to derive its optimal solutions. Numerical results on an IEEE system show that: (i) the devel...

Current DNA sequencing technologies do not read an entire chromosome from end to end but instead produce sets of short reads, i.e. fragments of the genome. Haplotype assembly is the problem of assigning each read to the correct chromosome in the set of chromosomes in a homologous group, with the aid of the reference sequence. In this paper, we extend an existing exact algorithm for haplotype as...

We consider the problem of augmenting a graph with n vertices embedded in a metric space, by inserting one additional edge in order to minimize the diameter of the resulting graph. We present an exact algorithm for the cases when the input graph is a path that runs in O(n log n) time. We also present an algorithm that computes a (1 + ε)approximation in O(n+1/ε) time for paths in R, where d is a...

In the Intervalizing Colored Graphs problem, one must decide for a given graph G = (V,E) with a proper vertex coloring of G whether G is the subgraph of a properly colored interval graph. For the case that the number of colors k is xed, we give an exact algorithm that uses O∗(2n/log (n)) time for all > 0. We also give an O∗(2n) algorithm for the case that the number of colors k is not xed.

in this paper we consider the non-preemptive variant of a multi-mode resource constrained project scheduling problem (mrcpsp) with mode identity, in which a set of project activities is partitioned into disjoint subsets while all activities forming one subset have to be processed in the same mode. we present a depth-first branch and bound algorithm for the resource constrained project schedulin...

This paper presents an algorithm for comparing large numbers of traces to each other and identifying and presenting groups of traces with similar features. It is applied to forensic analysis in which groups of similar traces are automatically identified and presented so that attribution and other related claims may be asserted, and independently confirmed or refuted. The approach of this paper ...

The primal-dual method increases the dual variables gradually until some dual constraint becomes tight. Then, the primal variable corresponding to the tight dual constraint is ‘bought’ (or selected), and the process continues till we get a feasible primal solution. Next, we compare the value of the primal solution to the value of the dual solution to get an appropriate approximation factor (or ...