#18948: Strongly Regular Graphs database
-------------------------+-------------------------------------------------
Reporter: | Owner:
ncohen | Status: positive_review
Type: | Milestone: sage-6.8
enhancement | Resolution:
Priority: major | Merged in:
Component: graph | Reviewers: Dima Pasechnik
theory | Work issues:
Keywords: | Commit:
Authors: | a75774fa9f6168b4f0e34c6cdd93496f7283b179
Nathann Cohen | Stopgaps:
Report Upstream: N/A |
Branch: |
u/ncohen/18948 |
Dependencies: |
-------------------------+-------------------------------------------------
Comment (by dimpase):
these graphs (O(5,q)) are available, but not known to your DB:
{{{
sage: o=graphs.OrthogonalPolarGraph(5,4)
sage: o.is_strongly_regular(parameters=True)
(85, 20, 3, 5)
sage: graphs.strongly_regular_graph(85, 20, 3, 5)
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call
last)
<ipython-input-29-152b95dceef4> in <module>()
----> 1 graphs.strongly_regular_graph(Integer(85), Integer(20),
Integer(3), Integer(5))
/home/dima/software/sage/src/sage/graphs/strongly_regular_db.pyx in
sage.graphs.strongly_regular_db.strongly_regular_graph
(build/cythonized/sage/graphs/strongly_regular_db.c:12463)()
1061 if existence:
1062 return True
-> 1063 raise RuntimeError(("Andries Brouwer's database claims
that such a "+
1064 "({},{},{},{})-strongly regular
graph exists, but "+
1065 "Sage does not know how to build
it. If *you* do, "+
RuntimeError: Andries Brouwer's database claims that such a
(85,20,3,5)-strongly regular graph exists, but Sage does not know how to
build it. If *you* do, please get in touch with us on sage-devel!
Comments: O(5,4) Sp(4,4); GQ(4,4)
sage:
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/18948#comment:29>
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