#20253: bug in strongly connected test for static digraphs
-------------------------------------+------------------------
Reporter: vdelecroix | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.2
Component: graph theory | Resolution:
Keywords: bug | Merged in:
Authors: Vincent Delecroix | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
-------------------------------------+------------------------
Changes (by {'newvalue': u'Vincent Delecroix', 'oldvalue': ''}):
* author: => Vincent Delecroix
Old description:
> Using the strongly connected graph from [https://graph-
> tool.skewed.de/performance this page] I got
> {{{
> sage: import networkx
> sage: g = networkx.read_graphml("pgp.xml")
> sage: networkx.is_strongly_connected(g)
> True
> sage: G = DiGraph(g)
> sage: G.is_strongly_connected()
> True
> }}}
> But the test goes wrong with the static sparse backend
> {{{
> sage: G2 = DiGraph(g, immutable=True)
> sage: G2.is_strongly_connected()
> False
> sage: G == G2
> True
> }}}
New description:
{{{
sage: G = DiGraph([(0,1),(1,0)])
sage: G2 = G.copy(immutable=True)
sage: G2.is_strongly_connected()
False
}}}
The problem comes from bad initialization of some attributes in static
sparse backend. We add two lines to fix this problem. We also deprecate
four methods of `CGraph` to simplify its usage (namely `_in_degree`,
`_out_degree`, `_num_verts`, `_num_arcs`).
--
--
Ticket URL: <http://trac.sagemath.org/ticket/20253#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
