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Open AccessJournal ArticleDOI

A transitive closure algorithm

Paul Walton Purdom
- 01 Mar 1970 - 
- Vol. 10, Iss: 1, pp 76-94
TLDR
An algorithm is given for computing the transitive closure of a directed graph in a time no greater than a1N1n+a2n2 for largen and the method uses aboutn2+n bits and 5n words of storage.
Abstract
An algorithm is given for computing the transitive closure of a directed graph in a time no greater thana1N1n+a2n2 for largen wherea1 anda2 are constants depending on the computer used to execute the algorithm,n is the number of nodes in the graph andN1 is the number of arcs (not counting those arcs which are part of a cycle and not counting those arcs which can be removed without changing the transitive closure). For graphs where each arc is selected at random with probabilityp, the average time to compute the transitive closure is no greater than min{a1pn3+a2n2, 1/2a1n2p−2+a2n2} for largen. The algorithm will compute the transitive closure of an undirected graph in a time no greater thana2n2 for largen. The method uses aboutn2+n bits and 5n words of storage (where each word can holdn+2 values).

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TL;DR: The value of depth-first search or “backtracking” as a technique for solving problems is illustrated by two examples of an improved version of an algorithm for finding the strongly connected components of a directed graph.
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Collaboration Processes: Inside the Black Box

TL;DR: The authors argue that public managers should look inside the "black box" of collaboration processes and find a complex construct of five variable dimensions: governance, administration, organizational autonomy, mutuality, and norms.
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The Transitive Reduction of a Directed Graph

TL;DR: It is shown that the time complexity of the best algorithm for finding the transitive reduction of a graph is the same as the time to compute the transitives closure of agraph or to perform Boolean matrix multiplication.
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Conflict-driven answer set solving: From theory to practice

TL;DR: An approach to computing answer sets of logic programs, based on concepts successfully applied in Satisfiability (SAT) checking, to view inferences in Answer Set Programming (ASP) as unit propagation on nogoods, and presents the first full-fledged algorithmic framework for native conflict-driven ASP solving.
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A survey of sparse matrix research

Iain S. Duff
TL;DR: This paper surveys the state of the art in sparse matrix research in January 1976, and discusses the solution of sparse simultaneous linear equations, including the storage of such matrices and the effect of paging on sparse matrix algorithms.
References
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EULER: a generalization of ALGOL, and its formal definition: Part II

TL;DR: In this section the algorithmic language EULER is described first informally and then formally by its syntax and semantics, creating a language which is simpler and yet more flexible than ALGOL 60.
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TL;DR: An algorithm for computing B is given which is especially suitable if the number of arcs in G is relatively small compared to thenumber of nodes, and which is probably most economical to Warshall.