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From "Marco Speranza (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (SANDBOX-337) Wrong value for Vertex degree
Date Sun, 03 Jul 2011 21:21:21 GMT

     [ https://issues.apache.org/jira/browse/SANDBOX-337?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Marco Speranza updated SANDBOX-337:
-----------------------------------

    Attachment:     (was: VertexDegreeTestCase.patch)

> 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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