منابع مشابه
Optimal Speedup of Las Vegas Algorithms
Let A be a Las Vegas algorithm, i.e., A is a randomized algorithm that always produces the correct answer when it stops but whose running time is a random variable. We consider the problem of minimizing the expected time required to obtain an answer from A using strategies which simulate A as follows: run A for a fixed amount of time t1 , then run A independently for a fixed amount of time t2 ,...
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We describe a general method to obtain quantum speedups of classical algorithms which are based on the technique of backtracking, a standard approach for solving constraint satisfaction problems (CSPs). Backtracking algorithms explore a tree whose vertices are partial solutions to a CSP in an attempt to find a complete solution. Assume there is a classical backtracking algorithm which finds a s...
متن کاملParallel Algorithms with Optimal Speedup for Bounded Treewidth
We describe the rst parallel algorithm with optimal speedup for constructing minimum-width tree decompositions of graphs of bounded treewidth. On n-vertex input graphs, the algorithm works in O((logn)) time using O(n) operations on the EREW PRAM. We also give faster parallel algorithms with optimal speedup for the problem of deciding whether the treewidth of an input graph is bounded by a given...
متن کاملNode Early-Fixing: A Practical Speedup Technique for A* Algorithms
Given a graph G with nonnegative edge lengths, a source vertex s and a destination vertex d, the Point-to-Point Shortest Path Problem asks to find a shortest path from s to d. For this problem, A* is a popular framework of practical algorithms, including the well-known Dijkstra’s algorithm (1959), a recent ALT algorithm (Goldberg and Harrelson, SODA’05) and others. This paper presents a practic...
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MOTIVATION Matching a biological sequence against a probabilistic pattern (or profile) is a common task in computational biology. A probabilistic profile, represented as a scoring matrix, is more suitable than a deterministic pattern to retain the peculiarities of a given segment of a family of biological sequences. Brute-force algorithms take O(NP) to match a sequence of N characters against a...
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ژورنال
عنوان ژورنال: Statistical Science
سال: 1993
ISSN: 0883-4237
DOI: 10.1214/ss/1177011079