Showing papers in "Journal of Discrete Algorithms in 2009"

TL;DR: This work generalizes Dijkstra's algorithm for finding shortest paths in digraphs with non-negative integral edge lengths bylabeling subgraphs which partition the given graph, which leads to considerably reduced running time.

TL;DR: This work discusses the impact that scheduling of index nodes can have on performance and shows that, unlike exact similarity queries, no provable optimal scheduling strategy exists for approximate queries.

TL;DR: In this article, the authors consider variants of the classical stable marriage problem in which preference lists may contain ties, and may be of bounded length, and they show that this problem is solvable in polynomial time if each man's list is of length at most 2 (even for women's lists that are of unbounded length).

TL;DR: In this paper, reoptimization versions of the traveling salesman problem (TSP) are addressed and it is shown that, dealing with metric MaxTSP, a simple heuristic is asymptotically optimum when a constant number of nodes are inserted.

TL;DR: This paper examines the parameterized complexity of the dual parameterized problem, namely, the k-Almostr-Regular Graph problem, which asks for a given graph G and a non-negative integer k whether G can be made r-regular by deleting at most k vertices and proves the existence of a problem kernel of size O(kr(r+k)^2).

TL;DR: For various values of t, NP-completeness and approximability results (both upper and lower bounds) and FPT algorithms for problems concerned with finding the minimum size of a t-total vertex cover, t- total edge cover and connected vertex cover are presented, in particular improving on a previous FPT algorithm for the latter problem.

TL;DR: Experimental results show that the algorithm outperforms all the previously known linear-time algorithms for 3-edge-connectivity in determining if a given graph is 3- Edge-connected and in determining cut-pairs and its performance is also among the best in determining the 3- edge-connected components.

TL;DR: A new metric index is devised, coined List of Twin Clusters (LTC), which indexes both sets jointly, instead of the natural approach of indexing one or both sets independently, and is shown how to use the LTC in order to solve classical range queries.

TL;DR: The presented results have a methodological interest because, to the best of the authors' knowledge, this is the first time when a new parameterized upper bound is obtained through design and analysis of an exact exponential algorithm.

TL;DR: This work develops a novel and unorthodox filtering technique based on transforming the problem into multiple matching of carefully chosen pattern subsequences that leads to very simple algorithms that are optimal on average.

TL;DR: This paper transforms a sequential index based on clustering into a distributed one and devise algorithms and optimizations specially tailored to support high-performance parallel query processing.

TL;DR: Two new techniques improving dynamic insertions in M-tree are proposed-the forced reinsertion strategies and so-called hybrid-way leaf selection, which aim to produce more compact M- tree hierarchies (which leads to faster query processing).

TL;DR: This paper considers the problem of removing c points from a set S of n points so that the remaining point set is optimal in some sense, and considers definitions of optimality that include having minimum diameter, having minimum area (perimeter) bounding box, and having minimum Area convex hull.

TL;DR: This work examines how many distinct permutations can occur as a function of the number of sites and the size of the space, and gives theoretical results for tree metrics and vector spaces with L"1, L"2, and L"~ metrics.

TL;DR: This paper investigates guessing number, a relatively new concept linked to network coding and certain long standing open questions in circuit complexity, and obtains the lower and upper bounds for shift graphs, a subclass of directed circulant graphs.

TL;DR: The paper deals with the worst case approximation ratio of the classic list scheduling algorithm 'Largest Processing Time (LPT)', and provides an analysis of this ratio Lpt/Opt for both special cases.

TL;DR: This work gives the first polynomial-time algorithm that computes the bandwidth of bipartite permutation graphs, which is an NP-complete graph layout problem that is notorious for its difficulty even on small graph classes.

TL;DR: The proved asymptotic PTAS for 2-dimensional Orthogonal Bin Packing (without rotations), unless P=NP is proved, is proved and similar approximation hardness results hold for several 2- and 3-dimensional rectangle packing and covering problems even if rotations by ninety degrees are allowed.

TL;DR: Given a set S of n red and blue points in the plane, a planar bichromatic minimum spanning tree is the shortest possible spanning tree of S, such that every edge connects a red and a blue point, and no two edges intersect.

TL;DR: The union of all inclusion-minimal k-hitting sets in hypergraphs of rank r is studied and it is shown that this union is relevant for certain combinatorial inference problems and worst-case bounds on its size are given, depending on r and k.

TL;DR: This paper presents a linear time algorithm for approximating the longest path length of a given directed acyclic graph (DAG), where each edge length is given as a normally distributed random variable.

TL;DR: This algorithm is then used to develop constant ratio approximation algorithms for the bounded depth Steiner tree problem and the bounded hop strong-connectivity range assignment problem.

TL;DR: This work derives special cases of numerical programs that require the intermediate values exactly in reverse order, thus establishing the NP-completeness of the optimal adjoint computation problem.

TL;DR: A new technique is provided that efficiently approximates a solution to this more general problem within a constant approximation ratio of 3.0 and appropriate generalizations of some common heuristics usually employed for the unweighted case are provided.

TL;DR: It is shown that fixed-vertex subgraph homeomorphism for a pattern graph on p vertices and a host graph on n vertices can be solved in time 2 n - p n O ( 1 ) or in time 3 n- p nO ( 1) and polynomial space.

TL;DR: Minimizing the total time spent to deliver loads L"1,...,L"n is equivalent to solving the traveling salesman problem (TSP) where the cities correspond to the loads with coordinates (@a"i,@b"i) and the distance from L"i to L"j is given by @!"@a"""i^@b^"^jf(x)dx if @b"j>[email protected]"i and by @!".

TL;DR: An extension of a classical data management subproblem, the page migration, is presented, which is investigated in dynamic networks, where costs of communication between different nodes may change with time.

TL;DR: It is shown that for any set of n points in the plane, there is an orthogonal spanner network that is short having a total edge length at most a constant times the length of a Euclidean minimum spanning tree for the point set.

TL;DR: In this paper, the authors presented an algorithm for enumerating all connected convex sets of an acyclic digraph D of order n. The time complexity of A is O( n? cc (D ), where cc(D ) is the number of connected conveX sets in D. In computational experiments, they demonstrate that their algorithms outperform the best algorithms in the literature.

TL;DR: In this paper, a recherche en cours relative a des situations de deuil au travail dans diverses moyennes et grandes entreprises is presented, basing sur quelques-uns of ces croisements disciplinaires and s’interroge sur la facon de penser le deul la ou s'exerce une activite professionnelle.