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From "Marco Speranza (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SANDBOX-337) Wrong value for Vertex degree
Date Sat, 02 Jul 2011 18:10:22 GMT
Wrong value for Vertex degree
-----------------------------

                 Key: SANDBOX-337
                 URL: https://issues.apache.org/jira/browse/SANDBOX-337
             Project: Commons Sandbox
          Issue Type: Bug
          Components: Graph
            Reporter: Marco Speranza
            Priority: Minor


Hi folk, I'm doing a tests case for the class BaseMutableGraph, in order to upgrade our testcase
suite. I think that our implementation of vertex degree is wrong.

according with http://en.wikipedia.org/wiki/Glossary_of_graph_theory#Adjacency_and_degree

"The degree, or valency, dG(v) of a vertex v in a graph G is the number of edges incident
to v, with loops being counted twice. A vertex of degree 0 is an isolated vertex. A vertex
of degree 1 is a leaf. In the labelled simple graph example, vertices 1 and 3 have a degree
of 2, vertices 2, 4 and 5 have a degree of 3, and vertex 6 has a degree of 1. If E is finite,
then the total sum of vertex degrees is equal to twice the number of edges."

so for a complete graph with 5 nodes, each vertex has a degree of 4. Instead our implementation
returns 8. 
IMHO this is wrong. WDYT?

Have a nice week end

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