Showing papers in "Journal of Algorithms in 2005"

TL;DR: In this paper, the authors introduce a sublinear space data structure called the countmin sketch for summarizing data streams, which allows fundamental queries in data stream summarization such as point, range, and inner product queries to be approximately answered very quickly; in addition it can be applied to solve several important problems in data streams such as finding quantiles, frequent items, etc.

TL;DR: The problem of finding lowest common ancestors (LCA) in trees and directed acyclic graphs (DAGs) is extended to DAGs and a close relationship between the LCA, all-pairs-shortest-path, and transitive-closure problems is revealed.

TL;DR: In this paper, the authors consider worst case time bounds for several NP-complete problems, based on a constraint satisfaction (CSP) formulation of these problems: (a, b)-CSP instances consist of a set of variables, each with up to a possible values, and constraints disallowing certain b-tuples of variable values; a problem is solved by assigning values to all variables satisfying all constraints.

TL;DR: In this paper, the first polynomial-time constant-factor approximation algorithm for disjoint convex fat neighborhoods of arbitrary size was presented, where the neighborhoods can overlap and are not required to be convex or fat.

TL;DR: The satisfiability problem on Boolean formulas in conjunctive normal form is considered and it is shown that a satisfying assignment of a formula can be found in polynomial time with a success probability of 2-n(1-1/(1+logm)), where n and m are the number of variables and the numberof clauses of the formula, respectively.

TL;DR: This work considers the setting of a network providing differentiated services and analyzes and compares different queue policies for this problem using the competitive analysis approach, where thebenefit of the online policy is compared to the benefit of an optimal offline policy.

TL;DR: This paper provides a linear time algorithm that for any input graph G, answers whether G has cutwidth at most k and, in the case of a positive answer, outputs the corresponding linear layout.

TL;DR: A dynamic programming algorithm is presented that finds a tour that visits at least OPT/density locations during their time windows and can be extended to deal with non-unit job profits and processing times.

TL;DR: It is shown how sparse dynamic programming can be used to solve transposition invariant problems, and its connection with multidimensional range-minimum search.

TL;DR: An algorithm is introduced that computes the natural coprime base for S in essentially linear time and can be used as a substitute for prime factorization in many applications.

TL;DR: This work shows how to construct an algorithm that, in n^O^(^w^^^2^d^) steps, computes the cutwidth of any partial w-tree with vertices of degree bounded by a fixed constant d.

TL;DR: An axiomatic characterization of the fair share is provided and it is shown that the FW share is the unique one satisfying these requirements.

TL;DR: The proposed algorithms improve the previous upper bounds from O (min{n|K|, n2}) for RLPW and from O(n |K|) for R LPWI and achieve linear time.

TL;DR: This paper presents a distributed algorithm for multicoloring hexagonal graphs using only the local clique numbers ω1( v) and ω2(v) at each vertex v of the given hexagonal graph, which can be computed from local information available at the vertex.

TL;DR: These algorithms are fast and simple, work for a variety of measures of partitioning quality, generalize to dimensions d > 2, and achieve almost optimal approximation ratios.

TL;DR: This paper proves that unlike the case where there is no existing facility, the continuous conditional median subtree problem is NP-hard and develops a corresponding fully polynomial approximation algorithm.

TL;DR: A very simple and efficient approach can be used to solve the all pairs almost shortest path problem on the class of weakly chordal graphs and its different subclasses and gives a unified way to solve all pairsalmost shortest path problems on different graph classes.

TL;DR: This work considers the data migration problem, which is the problem of finding an efficient schedule to migrate data in a network, and develops a 3-approximation algorithm when each migration job needs the same amount of time and a 9- approximation when the times required for different migration jobs are different.

TL;DR: It is shown that the greedy algorithm LPT has optimal competitive ratio 1/4(1 + √17) ≈ 1.28 overall, but does not have optimal competitive Ratio for every value of q, which gives a tight analysis of the competitive ratio for every speed ratio.

TL;DR: This work considers worst case time bounds for several NP-complete problems, based on a constraint satisfaction (CSP) formulation of these problems: (a, b)-CSP instances consist of a set of variables, each of which represents a constraint.

TL;DR: In this article, the authors give an algorithm to minimize the total completion time on a single machine, using restarts, with a competitive ratio of 3/2. This is the first restarting algorithm that is proved to be better than an algorithm that does not restart.

TL;DR: A simple polynomial-time algorithm is presented that recognises reflexive, symmetric graphs admitting a near-unanimity operation and several other characterisations of these graphs are presented.

TL;DR: For arbitrary metric spaces, the k-server problem can be approached by using probabilistic metric approximation techniques as discussed by the authors, and the first results in this direction were obtained by obtaining o(k)-competitive ratio for a natural class of metric spaces.

TL;DR: It is shown that the problems of minimizing total completion time and of minimizing the number of late jobs on unrelated parallel machines, when preemption is allowed, are both NP-hard in the strong sense.

TL;DR: In this article, it was shown that the problem of minimizing total completion time and minimizing the number of late jobs on unrelated parallel machines, when preemption is allowed, is NP-hard.

TL;DR: A simple probabilistic guessing algorithm that allows us to guess all secrets of S with probability one is defined and it is shown that the expected number of questions needed to Guess all secrets is 2n2log2N and the expected time complexity of the algorithm is O( n2logN).

TL;DR: A sampling algorithm for general datasets which gives estimates strictly better than the largest sample for an infinite family of datasets is given, which overshoots the true maximum of the worst case dataset with probability at most (1/e) + O( 1/k).

TL;DR: In this article, it was shown that Longest In System (LIIS) protocol for directed acyclic graphs uses buffers of only linear size (in the length of the longest path in the network) and any packet incurs only linear delay.

TL;DR: The string matching with mismatches problem requires finding the Hamming distance between a pattern P of length m and every length m substring of text T with length n, which in the worst case reduces to O(nmlogm).

TL;DR: An easy algorithm is described a special case of which will generate a list of all n-ary Huffman sequences of length m, for any given integers m ≥ 1, n ≥ 2.