Hi Jason, On Nov 23, 3:42 pm, Jason Grout <jason-s...@creativetrax.com> wrote: > I'm trying to get a list of all groups of order 60. After searching for > a bit, I see in Gap that (if I install the optional spkg > database_gap-4.4.12.p0.spkg) we have the AllSmallGroups command, which > seems to do what I want. But then I'm having problems converting those > groups to Sage groups: > > sage: gg=gap.AllSmallGroups(60) > sage: gg[1]._sage_() > --------------------------------------------------------------------------- > NotImplementedError Traceback (most recent call last) > > /Users/grout/<ipython console> in <module>() > > /Users/grout/sage/local/lib/python2.6/site-packages/sage/interfaces/expect.pyc > in _sage_(self) > 1709 return sage.misc.sage_eval.sage_eval(self._sage_repr()) > 1710 except: > -> 1711 raise NotImplementedError > 1712 > 1713 > > NotImplementedError:
That is a common thing. Gap-to-sage conversion relies more often than not on trying to parse the gap string of the object, if sage doesn't understand the string the conversion will fail. In general gap-to-sage conversion is hard because gap objects don't have a "type". However, since in gap there are a lot of Is* functions, one could just develop a consistent way of checking gap objects until it is clear what they are, and program specific "to-sage" conversion functions like the one done for matrices over finite groups. > > Question 1: Is there a command in Sage that will give all groups of a > certain order (maybe just the orders covered by the small group database > in GAP)? I am afraid not. > Question 2: Is there an easy way to convert a GAP group to a Sage group? I don't know if I'd call it "easy" but one thing you can do is to transform your group to a permutation group and the translate that into sage: sage: gg = gap.AllSmallGroups(60) sage: gg1 = gg[1] sage: iso = gg1.IsomorphismPermGroup() sage: gg2 = iso.Image() sage: gens = gg2.GeneratorsSmallest() sage: G1 = PermutationGroup(gens) sage: type(G1) <class 'sage.groups.perm_gps.permgroup.PermutationGroup_generic_with_category'> sage: G1.order() 60 this can be useful for small groups, but I am afraid it would be terribly inefficient for large ones. A better way would be implementing general groups with generators and relations in sage, but I don't know if any work has been done along these lines. Cheers Javier -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
