#19586: Add is_cayley_graph
-------------------------------------+-------------------------------------
Reporter: jaanos | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.10
Component: graph theory | Resolution:
Keywords: Cayley graphs | Merged in:
groups | Reviewers:
Authors: Janoš Vidali | Work issues:
Report Upstream: N/A | Commit:
Branch: | 4aaf3014fee5bb08d861636908d6733047d4a869
u/jaanos/add_is_cayley_graph | Stopgaps:
Dependencies: |
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Comment (by dimpase):
Replying to [comment:37 ncohen]:
> > IMHO it's also against the spirit of OOP to have an option in a
function `f` to return either `X` or `X.blah()`; the user can call
`.blah()` on the answer he gets himself; and `X` is already created in
`f`, there is no performance gain in returning X.blah() instead of `X`.
>
> Are we sure that a permuation group defined from a set of generators
returns the *very same* set of generators when you call `.gen()`? Or could
they be simplified/reduced if Gap believe that another representation is
better?
In GAP `GeneratorsOfGroup` need not return the original list of generators
used to define the group in the first place.
{{{
39.2-2 GroupByGenerators
‣ GroupByGenerators( gens )
──────────────────────────────────────────────────────────────── operation
‣ GroupByGenerators( gens, id )
──────────────────────────────────────────────────────────── operation
GroupByGenerators returns the group G generated by the list gens. If a
second argument id is present
then this is stored as the identity element of the group.
The value of the attribute GeneratorsOfGroup (39.2-4) of G
need not be equal to gens.
GroupByGenerators is the underlying operation called by Group (39.2-1).
}}}
I don't know how to recover the original generators from `Group`; it could
very well be that they get lost, by design.
--
Ticket URL: <http://trac.sagemath.org/ticket/19586#comment:38>
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