Circuit rank: Difference between revisions

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===Definition for a finite graph===
===Definition for a finite graph===


Suppose <math>G</math> is a [[finite graph|finite]] [[undirected graph]]. The '''circuit rank''' of <math>G</math>, also called the '''cyclotomic number''' of <math>G</math>, is defined in the following equivalent ways:
Suppose <math>G</math> is a [[finite graph|finite]] [[undirected graph]]. The '''circuit rank''' of <math>G</math>, also called the '''cyclomatic number''' of <math>G</math>, is defined in the following equivalent ways:


# It is the minimum number of edges that needs to be removed from the edge set of <math>G</math> to make it a [[forest]] (i.e., an acyclic graph)
# It is the minimum number of edges that needs to be removed from the edge set of <math>G</math> to make it a [[forest]] (i.e., an acyclic graph)
# It is given by <math>|E(G)| - |V(G)| + c</math> where <math>V(G)</math> is the vertex set, <math>E(G)</math> is the edge set, and <math>c</math> is the number of conncted components of <math>G</math>.
# It is given by <math>|E(G)| - |V(G)| + c</math> where <math>V(G)</math> is the vertex set, <math>E(G)</math> is the edge set, and <math>c</math> is the number of conncted components of <math>G</math>.

Revision as of 18:18, 28 May 2012

Template:Undirected graph numerical invariant

Definition

Definition for a finite graph

Suppose is a finite undirected graph. The circuit rank of , also called the cyclomatic number of , is defined in the following equivalent ways:

  1. It is the minimum number of edges that needs to be removed from the edge set of to make it a forest (i.e., an acyclic graph)
  2. It is given by where is the vertex set, is the edge set, and is the number of conncted components of .