Showing papers in "Journal of Algorithms in 2001"

TL;DR: This paper introduces several simple and new techniques that lead to an improved algorithm of time O(kn+1.2852k) for the Vertex Cover problem, and induces improvement on previous algorithms for the Independent Set problem on graphs of small degree.

TL;DR: It is shown that if a graph has a vertex cover of size k, then one can select in polynomial time a set of k vertices that covers over 80% of the edges.

TL;DR: This paper shows that the weighted version and four variants of the unweighted version of the biclique problem are NP-complete, and provides a special case in which edge weighted versions are polynomially solvable.

TL;DR: The development of techniques to use the succinct tree representation through balanced parentheses for suffix trees and several index structures for binary texts, with less space are given.

TL;DR: An approximation algorithm for the weighted k-set packing problem is presented that combines the two paradigms by starting with an initial greedy solution and then repeatedly choosing the best possible local improvement, which is the first asymptotic improvement over the straightforward ratio of k.

TL;DR: It is shown that if the weights are homogeneous (i.e., proportional to the potential coverage of the sets) then any minimal cover is a good approximation, and it is sufficient to repeatedly subtract a homogeneous weight function from the given weight function.

TL;DR: Radio networks that are subject to permanent node failures of unknown location are considered, giving broadcasting algorithms whose worst-case running time has optimal order of magnitude, and corresponding lower bounds are proved.

TL;DR: The ordered tree-to-tree correction problem is to compute the minimum edit cost of transforming one ordered tree to another one, and a new algorithm is presented for this problem, which is asymptotically faster for certain kind of trees.

TL;DR: A practical algorithm with an O(n+m?(m,n) time bound and a variant with a linear time bound is given and a unique decomposition of the vertices into nested modules is described.

TL;DR: This work gives the first algorithm with a nontrivial performance guarantee for the problem of locating a set of points such that the sum of their distances to their nearest neighbor in the set is maximized.

TL;DR: Three algorithms for finding small-stretch paths between all pairs of vertices in a weighted graph with n vertices and m edges are described.

TL;DR: This paper proves that some of the layout problems on a family of random geometric graphs remain NP-complete even for geometric graphs, and presents two heuristics that, almost surely, turn out to be constant approximation algorithms for their layout problems.

TL;DR: A combinatorial algorithm is presented that achieves a similar approximation ratio but runs in O(n3) time and is based on a new and simple lower bound which the author believes is of independent interest.

TL;DR: Improved approximation algorithms for several rectangle tiling and packing problems (RTILE, DRTILE, and d-RPACK) studied in the literature are provided and the best known approximation ratios are improved.

TL;DR: This paper presents polynomial-time approximation algorithms for the problem of computing a maximum independent set in a given map graph G with or without weights on its vertices.

TL;DR: An algorithm for comparing trees that are labeled in an arbitrary manner is presented, which is faster than the previous algorithms and an efficient algorithm is obtained for a new matching problem called the hierarchical bipartite matching problem.

TL;DR: This work considers the problem of testing the uniqueness of maximum matchings, both in the unweighted and in the weighted case, and gives a modification of the first algorithm that tests whether a given graph has a unique f-factor, and finds it if it exists.

TL;DR: A unified treatment of parameters relevant to factoring polynomials over finite fields is given, based on generating functions for describing parameters of interest and on singularity analysis for extracting asymptotic values.

TL;DR: Two approximation algorithms for the coloring problem and the maximum independent set problem in 3-uniform hypergraphs are discussed and results are obtained through semidefinite programming relaxations of these optimization problems.

TL;DR: This work provides a nontrivial so-called fixed parameter algorithm for CBVC, running in O(1.3999k1-k2+(k1+k2)n) time, which is efficient and practical for small values of k1 and k2, as occurring in applications.

TL;DR: This paper describes an algorithm which is composed of an encoding stage and an alignment stage, and shows how to reduce the O(n?) alignment work, for each appearance of the common substring Y in a source string, to O-at the cost of O( n?) encoding work, which is executed only once.

TL;DR: In this paper, a new method of constructing approximation algorithms for combinatorial optimization problems using semidefinite programming is introduced, which is based on expressing each combinatory object in the original problem as a constellation of vectors in the semi-definite program.

TL;DR: A semidefinite programming relaxation of MAX 4-SAT and a new family of rounding procedures that try to cope well with clauses of various sizes are presented and believed to have a much wider range of applicability.

TL;DR: This work presents the first randomized O(logn) time and O(m+n) work EREW PRAM algorithm for finding a spanning forest of an undirected graph G=(V,E) with n vertices and m edges.

TL;DR: The problem of computing a minimum edge ranking spanning tree (MERST), i.e., find a spanning tree of a given graph G whose edge ranking is minimum, is introduced and it is shown that problem MERST is NP-hard.

TL;DR: This paper presents a simple randomized O(log2.5n)-approximation algorithm for bandwidth minimization on trees and shows that a close variant of this algorithm gives a similar performance guarantee for chordal graphs.

TL;DR: The probabilistic model includes random proper colorings, random independent sets, and the Widom?Rowlinson and Beach models of statistical physics, which prove negative results for uniform sampling and a positive result for weighted sampling when H is a tree.

TL;DR: This work is able to obtain subquadratic algorithms to find the cheapest path from s to all other airports for any well-behaved cost function l, and shows a quadratic lower bound on the combinatorial complexity of this map for a class of cost functions.

TL;DR: A new style of drawing a plane graph G, called proper box rectangular (PBR) drawing, defined to be a drawing of G such that every vertex is drawn as a rectangle, called a box, each edge isdrawn as either a horizontal or a vertical line segment, and each face is drawnAs a rectangle.

TL;DR: This study has developed a very simple algorithm with time complexity O(k?32)k?1·(n?k)2k?4·nk? 32k2+12k]·log(n)?k based on some simple theorems that characterize the structure of the k-way cut.