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AnO(m + n log n) Algorithm for the Maximum-Clique Problem in Circular-Arc Graphs

✍ Scribed by Binay K. Bhattacharya; Damon Kaller


Publisher
Elsevier Science
Year
1997
Tongue
English
Weight
338 KB
Volume
25
Category
Article
ISSN
0196-6774

No coin nor oath required. For personal study only.

✦ Synopsis


We present an algorithm to compute, in O m q n log n time, a maximum clique Ž . in circular-arc graphs with n vertices and m edges provided a circular-arc model of the graph is given. If the circular-arc endpoints are given in sorted order, the Ž . time complexity is O m . The algorithm operates on the geometric structure of the circular arcs, radially sweeping their endpoints; it uses a very simple data structure consisting of doubly linked lists. Previously, the best time bound for this problem Ž . was O m log log n q n log n , using an algorithm that solved an independent subproblem for each of the n circular arcs. By using the radial-sweep technique, we need not solve each of these subproblems independently; thus we eliminate the log log n factor from the running time of earlier algorithms. For vertex-weighted Ž circular-arc graphs, it is possible to use our approach to obtain an O m log log n q . n log n algorithm for finding a maximum-weight cliqueᎏwhich matches the best known algorithm.


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