#17627: Construction of FinitelyGeneratedGroup from GAP group
-------------------------------------+-------------------------------------
Reporter: vdelecroix | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.5
Component: group theory | Resolution:
Keywords: | Merged in:
Authors: Sergey Bykov | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/captaintrunky/construction_of_finitelygeneratedgroup_from_gap_group|
9d36df8c6f01d89e631b8f0a0e18ce5cdb7b34ec
Dependencies: | Stopgaps:
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Changes (by vdelecroix):
* cc: ​mmarco (added)
* status: needs_review => needs_work
Old description:
> It should be possible to initialize a `FinitelyPresentedGroup` (in
> `sage.groups.finitely_presented_group`) directly from a GAP group.
New description:
It should be possible to initialize a `FinitelyPresentedGroup` (in
`sage.groups.finitely_presented_group`) directly from a GAP group as
follows
{{{
sage: F_gap = libgap.FreeGroup("x", "y")
sage: x,y = libgap.GeneratorsOfGroup(F_gap)
sage: rels_gap = libgap([x**2, y**3, (x*y)**5])
sage: G_gap = F_gap / rels_gap
sage: libgap.IsFpGroup(G_gap)
true
sage: from sage.groups.finitely_presented import FinitelyPresentedGroup
sage: FinitelyPresentedGroup(G_gap)
# DOES NOT WORK
sage: G_gap.sage()
# DOES NOT WORK
}}}
Even with free groups it fails
{{{
sage: FreeGroup(F_gap)
# DOES NOT WORK
sage: F_gap.sage()
# DOES NOT WORK
}}}
--
Comment:
What I had in mind and is now described in the ticket description was the
case of one argument sent to `FinitelyPresentedGroup`. Your solution
solves the case when the '''free group''' provided is a gap group. The
latter case should be handled directly in `FreeGroup` and not in
`FinitelyPresentedGroup`. And by the way, it is '''always''' a bad idea to
inject variables in a function.
--
Ticket URL: <http://trac.sagemath.org/ticket/17627#comment:13>
Sage <http://www.sagemath.org>
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