2014 | OriginalPaper | Chapter
Detecting Maximum k-Plex with Iterative Proper ℓ-Plex Search
Authors : Yoshiaki Okubo, Masanobu Matsudaira, Makoto Haraguchi
Published in: Discovery Science
Publisher: Springer International Publishing
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In this paper, we are concerned with the notion of
k
-plex, a relaxation model of clique, where degree of relaxation is controlled by the parameter
k
. Particularly, we present an efficient algorithm for detecting a
maximum k-plex
in a given simple undirected graph. Existing algorithms for extracting a maximum
k
-plex do not work well for larger
k
-values because the number of
k
-plexes exponentially grows as
k
becomes larger. In order to design an efficient algorithm for the problem, we introduce a notion of
properness
of
k
-plex. Our algorithm tries to
iteratively
find a maximum proper ℓ-plex, decreasing the value of ℓ from
k
to 1. At each iteration stage, the maximum size of proper ℓ-plex found so far can work as an effective lower bound which makes our branch-and-bound pruning more powerful. Our experimental results for several benchmark graphs show that our algorithm can detect maximum
k
-plexes much faster than
SPLEX
, the existing most efficient algorithm.