#9136: more named graphs
----------------------------+-----------------------------------------------
Reporter: mvngu | Owner: jason, ncohen, rlm
Type: enhancement | Status: new
Priority: major | Milestone: sage-wishlist
Component: graph theory | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by dimpase):
Many of these graphs can be trivially generated in GAP using its package
Grape (a part of the optional gap_packages spkg) and
a library of primitive groups (a part of optional databases_gap spkg).
E.g. here is how to get Schlaefli graph:
{{{
sage: gap.load_package('grape')
sage: gap.eval('G:=NullGraph(PrimitiveGroup(27,12),27);')
'rec( isGraph := true, order := 27, group := PSp(4, 3), \n schreierVector
:= [ -1, 1, 2, 1, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 2, 1, \n 2, 1,
1, 2, 2, 1, 1, 1, 2 ], adjacencies := [ [ ] ], \n representatives := [ 1
], isSimple := true )'
sage: gap.eval('AddEdgeOrbit(G,[1,2]);')
''
sage: gap.eval('VertexDegrees(G);')
'[ 10 ]'
sage: edges=gap('Orbit(G.group,[1,2],OnSets)')
sage: len(edges)
135
sage: schlaefli=Graph([[int(x[1])-1,int(x[2])-1] for x in edges])
sage: schlaefli.degree()
[10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 10]
sage: schlaefli.diameter()
2
}}}
IMHO there is a more fundamental issue here: Sage should handle such
graphs in an efficient way --- just keeping all the edges is pretty much a
waste, in particular for bigger examples with hundreds of vertices...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9136#comment:7>
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