#20800: The document of strongly_connected_components for Digraphs is not
consistent with its behaviour
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Reporter: tmonteil | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.3
Component: graph theory | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by tmonteil:
Old description:
> As reported in [http://ask.sagemath.org/question/33735/finding-number-of-
> strongly-connected-components/ this ask question], the document says:
>
> {{{
> This routine returns a pair "[nscc, scc]", where "nscc" is the
> number of SCCs and "scc" is a dictionary associating to each vertex
> "v" an integer between "0" and "nscc-1", corresponding to the SCC
> containing "v". SCCs are numbered in reverse topological order,
> that is, if "(v,w)" is an edge in the graph, "scc[v] <= scc[w]".
> }}}
>
> while the method returns a list of lists of vertices, see:
>
> {{{
> sage: G = digraphs.DeBruijn(2,2)
> sage: G.strongly_connected_components()
> [['00', '01', '10', '11']]
> sage: G.strongly_connected_components?
> }}}
>
> The documentation itself shows examples of this, so the description
> should be updated.
New description:
As reported in [http://ask.sagemath.org/question/33735/finding-number-of-
strongly-connected-components/ this ask question], the document says:
{{{
This routine returns a pair "[nscc, scc]", where "nscc" is the
number of SCCs and "scc" is a dictionary associating to each vertex
"v" an integer between "0" and "nscc-1", corresponding to the SCC
containing "v". SCCs are numbered in reverse topological order,
that is, if "(v,w)" is an edge in the graph, "scc[v] <= scc[w]".
}}}
while the method returns a list of lists of vertices, see:
{{{
sage: G = digraphs.DeBruijn(2,2)
sage: G.strongly_connected_components()
[['00', '01', '10', '11']]
sage: G.strongly_connected_components?
}}}
The documentation itself shows examples of this, so the description should
be updated, or the method (and examples) updated.
--
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Ticket URL: <http://trac.sagemath.org/ticket/20800#comment:1>
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