Results 1 
8 of
8
A Comparative Study of kShortest Path Algorithms
 In Proc. of 11th UK Performance Engineering Workshop
, 1995
"... Efficient management of networks requires that the shortest route from one point (node) to another is known; this is termed the shortest path. It is often necessary to be able to determine alternative routes through the network, in case any part of the shortest path is damaged or busy. The kshortes ..."
Abstract

Cited by 17 (0 self)
 Add to MetaCart
Efficient management of networks requires that the shortest route from one point (node) to another is known; this is termed the shortest path. It is often necessary to be able to determine alternative routes through the network, in case any part of the shortest path is damaged or busy. The kshortest paths represent an ordered list of the alternative routes available. Four algorithms were selected for more detailed study from over seventy papers written on this subject since the 1950's. These four were implemented in the `C' programming language and, on the basis of the results, an assessment was made of their relative performance. 1 The Background The shortest path through a network is the least cost route from a given node to another given node, and this path will usually be the preferred route between those two nodes. When the shortest path between two nodes is not available for some reason, it is necessary to determine the second shortest path. If this too is not available, a thir...
Deviation Algorithms For Ranking Shortest Paths
, 1999
"... The shortest path problem is a classical network problem that has been extensively studied. The problem of determining not only the shortest path, but also listing the K shortest paths (for a given integer K ? 1) is also a classical one but has not been studied so intensively, despite its obvious p ..."
Abstract

Cited by 17 (5 self)
 Add to MetaCart
The shortest path problem is a classical network problem that has been extensively studied. The problem of determining not only the shortest path, but also listing the K shortest paths (for a given integer K ? 1) is also a classical one but has not been studied so intensively, despite its obvious practical interest. Two different types of problems are usually considered: the unconstrained and the constrained K shortest paths problem. While in the former no restriction is considered in the definition of a path, in the constrained K shortest paths problem all the paths have to satisfy some condition  for example, to be loopless. In this paper new algorithms are proposed for the unconstrained problem, which compute a super set of the K shortest paths. It is also shown that ranking loopless paths does not hold in general the Optimality Principle and how the proposed algorithms for the unconstrained problem can be adapted for ranking loopless paths. Keywords: Network, tree, path, path d...
On Suboptimal Alignments of Biological Sequences
 Proc. 4th Symp. on Combinatorial Pattern Matching
, 1993
"... . It is widely accepted that the optimal alignmentbetween a pair of proteins or nucleic acid sequences that minimizes the edit distance may not necessarily re#ect the correct biological alignment. Alignments of proteins based on their structures or of DNA sequences based on evolutionary changes ..."
Abstract

Cited by 10 (0 self)
 Add to MetaCart
. It is widely accepted that the optimal alignmentbetween a pair of proteins or nucleic acid sequences that minimizes the edit distance may not necessarily re#ect the correct biological alignment. Alignments of proteins based on their structures or of DNA sequences based on evolutionary changes are often di#erent from alignments that minimize edit distance. However, in many cases #e.g. when the sequences are close#, the edit distance alignment is a good approximation to the biological one. Since, for most sequences, the true alignment is unknown, a method that either assesses the signi#cance of the optimal alignment, or that provides few #close" alternatives to the optimal one, is of great importance. A suboptimal alignment is an alignment whose score lies within the neighborhood of the optimal score. Enumeration of suboptimal alignments #Wa83, WaBy# is not very practical since there are many such alignments. Other approaches #Zuk, Vi, ViAr# that use only partial informat...
Finding the k Shortest Paths in Parallel
, 2000
"... . A concurrentread exclusivewrite PRAM algorithm is developed to find the k shortest paths between pairs of vertices in an edgeweighted directed graph. Repetitions of vertices along the paths are allowed. The algorithm computes an implicit representation of the k shortest paths to a given destina ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
. A concurrentread exclusivewrite PRAM algorithm is developed to find the k shortest paths between pairs of vertices in an edgeweighted directed graph. Repetitions of vertices along the paths are allowed. The algorithm computes an implicit representation of the k shortest paths to a given destination vertex from every vertex of a graph with n vertices and m edges, using O(m +nk log 2 k) work and O(log 3 k log # k + log n(log log k +log # n)) time, assuming that a shortest path tree rooted at the destination is precomputed. The paths themselves can be extracted from the implicit representation in O(log k +log n) time, and O(n log n+L) work, where L is the total length of the output. Key Words. Parallel graph algorithms, Data structures, Shortest paths. 1. Introduction. The problem of finding shortest paths in an edgeweighted graph is an important and wellstudied problem in computer science. The more general problem of computing the k shortest paths between vertices of...
Generating kBest Solutions to Auction Winner Determination Problems
"... Auction participants cannot always articulate their requirements and preferences. Sometimes, for instance, the buyer in a procurement auction cannot quantify the value of nonprice solution attributes or delineate between hard and soft constraints. This precludes formulating the winner determination ..."
Abstract

Cited by 3 (1 self)
 Add to MetaCart
Auction participants cannot always articulate their requirements and preferences. Sometimes, for instance, the buyer in a procurement auction cannot quantify the value of nonprice solution attributes or delineate between hard and soft constraints. This precludes formulating the winner determination problem (WDP) as an optimization problem. Existing decisionsupport aids for such situations extend an optimization framework. We present an approach that frames the decision problem as one of exploration rather than optimization. Our method relies on an algorithm that generates kbest solutions to auction WDPs. Our algorithm can incorporate hard constraints into the generation process and can scale to practical procurement auctions. We show how to extract useful guidance from kbest WDP solutions, and we evaluate our method using real bids submitted by real suppliers in an HP material parts procurement auction.
Parallel Algorithms for the k Shortest Paths and Related Problems
, 1996
"... A parallel algorithm is developed to find the k shortest paths between pairs of vertices in an edgeweighted directed graph. The concurrentread exclusivewrite PRAM is used as the model of computation. The algorithm computes an implicit representation of the k shortest paths to a given destination ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
A parallel algorithm is developed to find the k shortest paths between pairs of vertices in an edgeweighted directed graph. The concurrentread exclusivewrite PRAM is used as the model of computation. The algorithm computes an implicit representation of the k shortest paths to a given destination vertex from each vertex of a graph with n vertices and m edges, using O(m + nk log 2 k) work and O(log 3 k log k + log n(log log k + log n)) time, assuming that a shortest path tree rooted at the destination is precomputed. Parallel algorithms are also described for a weighted version of the problem of selecting an element of given rank from an unsorted array and for the selection of the kth smallest element in a matrix with sorted columns. The k shortest paths algorithm is applied to obtain a parallel implementation of a dynamic programming algorithm for the list Viterbi decoding problem, where one must find the most probable state sequences of a Markov process, given noisy obser...
Decision Support Systems With Multiple Choice Structure
 In "Numbers, Information and Complexity" (Editors
, 1999
"... In the "Triple Brain" approach ("3Hirn" in German) one human and two computers with different programs are involved. Both programs are started and present one solution each. The human is a controller. He inspects the computer solutions and selects one of them. The human is not allowed to outvote th ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
In the "Triple Brain" approach ("3Hirn" in German) one human and two computers with different programs are involved. Both programs are started and present one solution each. The human is a controller. He inspects the computer solutions and selects one of them. The human is not allowed to outvote the machines. "Triple Brain" is a "Decision Support System with Multiple Choice Structure": Computer programs (one or several) provide a handful of interesting candidate solutions, and a controller (typically a human) has the final choice among these candidates. This article exhibits and discusses various aspects of Decision Support Systems with Multiple Choice Structure. Key Words and Phrases: Triple Brain, 3Hirn, Decision Support System, Multiple Choice, Multiple Choice System, man and machine, kbest algorithm, kbest optimization under side constraints, incremental computing; 1 Introduction Humans are able to think, to feel, and to sense. We can also compute, but not too well. Instead,...
Development and Testing of Dynamic Traffic Assignment . . .
, 1994
"... This report describes the methodologies and procedures developed through a contract to the University of Texas at Austin, in collaboration with the University of Maryland, to address these essential needs. Specifically, a simulationassignment methodology has been developed to describe user's path ..."
Abstract
 Add to MetaCart
This report describes the methodologies and procedures developed through a contract to the University of Texas at Austin, in collaboration with the University of Maryland, to address these essential needs. Specifically, a simulationassignment methodology has been developed to describe user's path choices in the network in response to realtime information, and the resulting flow patterns that propagate through the network, yielding information about overall quality of service and effectiveness, as well as localized information pointing to problem spots and opportunities for improvement. This methodology is intended for use offline for evaluation purposes, or online for prediction purpose in support of advanced traffic management functions. In additional, algorithmic procedures have been developed to determine the best paths to which users should be directed so as to optimize overall system performance. Powerful extension