Counting and Detecting Small Subgraphs via Equations
Counting and Detecting Small Subgraphs via Equations
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通过方程计算和检测小子图
DOI:
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发表时间:
2013
影响因子:
0.8
通讯作者:
E. Lundell
中科院分区:
文献类型:
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作者:
Miroslaw Kowaluk;A. Lingas;E. Lundell
We present a general technique for detecting and counting small subgraphs. It consists of forming special linear combinations of the numbers of occurrences of different induced subgraphs of fixed size in a graph. These combinations can be efficiently computed by rectangular matrix multiplication. Our two main results utilizing the technique are as follows. Let $H$ be a fixed graph with $k$ vertices and an independent set of size $s.$ 1. Detecting if an $n$-vertex graph contains a (not necessarily induced) subgraph isomorphic to $H$ can be done in time $O(n^{omega(lceil (k-s)/2
ceil, 1, lfloor (k-s)/2
floor )})$, where $omega (p,q,r)$ is the exponent of fast arithmetic matrix multiplication of an $n^p imes n^q$ matrix by an $n^q imes n^r$ matrix. 2. When $s=2,$ counting the number of (not necessarily induced) subgraphs isomorphic to $H$ can be done in the same time, i.e., in time $O(n^{omega(lceil (k-2)/2
ceil, 1, lfloor (k-2)/2
floor )}).$ It follows in particular that we can count the nu...