On Thursday, March 24, 2016 at 6:36:55 AM UTC, Dima Pasechnik wrote: > > > > On Wednesday, March 23, 2016 at 11:10:42 PM UTC, Jernej wrote: >> >> Hello! >> >> Thanks! I wasn't aware of libgap! One more followup question. Say I want >> to compute the orbits of the CubeGraph of order 10. The description of >> respective automorphism group seems to be to heave for libgap >> >> ==== >> sage: G = graphs.CubeGraph(10) >> sage: G.relabel() >> sage: A = G.automorphism_group() >> sage: libgap(A) >> python: libgap.c:186: libgap_get_input: Assertion >> `strlen(libGAP_stdin_buffer) < length' failed. >> === >> >> Is there a way to overcome this limitation? >> > > sage: G = graphs.CubeGraph(10) > sage: A = G.automorphism_group() > sage: T=libgap.Group(map(libgap,A.gens())) > sage: T.Order() > 3715891200 > > works. > There is probably a fixed side buffer somewhere that is not big enough for > passing the whole of A > directly. > I suppose it is the assertion here: https://bitbucket.org/vbraun/libgap/src/0273a81b021a35ff6ce18d8a2c41be5144c872c3/src/libgap.c?at=master&fileviewer=file-view-default#libgap.c-184
perhaps Volker knows the problem behind this error. > >> Best, >> >> Jernej >> >> On Tuesday, 22 March 2016 14:18:56 UTC+1, Dima Pasechnik wrote: >>> >>> >>> >>> On Tuesday, March 22, 2016 at 1:09:07 PM UTC, Dima Pasechnik wrote: >>>> >>>> use libgap: >>>> >>>> sage: g=libgap.SymmetricGroup(7) >>>> sage: g.Orbits(tuples([1..7],2),libgap.OnTuples) >>>> [ [ [ 1, 1 ], [ 2, 2 ], [ 3, 3 ], [ 4, 4 ], [ 5, 5 ], [ 6, 6 ], [ 7, 7 >>>> ] ], [ [ 1, 2 ], [ 2, 3 ], [ 2, 1 ], [ 3, 4 ], [ 1, 3 ], [ 3, 2 ], [ 4, 5 >>>> ], [ 2, 4 ], [ 4, 3 ], [ 3, 1 ], [ 5, 6 ], [ 3, 5 ], [ 1, 4 ], [ 5, 4 ], [ >>>> 4, 2 ], [ 6, 7 ], [ 4, 6 ], [ 2, 5 ], [ 6, 5 ], [ 5, 3 ], [ 4, 1 ], [ 7, 1 >>>> ], [ 5, 7 ], [ 3, 6 ], [ 1, 5 ], [ 7, 6 ], [ 6, 4 ], [ 5, 2 ], [ 7, 2 ], [ >>>> 6, 1 ], [ 4, 7 ], [ 2, 6 ], [ 1, 7 ], [ 7, 5 ], [ 6, 3 ], [ 5, 1 ], [ 6, 2 >>>> ], [ 3, 7 ], [ 1, 6 ], [ 2, 7 ], [ 7, 4 ], [ 7, 3 ] ] ] >>>> >>>> if you only need representatives, you can just use map: >>> >>> map(lambda x: x[0], g.OrbitsDomain(tuples([1..7],2),libgap.OnTuples)) >>> >>> (Here I used OrbitsDomain, which you should use for efficiency if you >>> know that your set is invariant under your >>> group) >>> >>> >>>> On Tuesday, March 22, 2016 at 9:19:18 AM UTC, Jernej wrote: >>>>> >>>>> Hello! >>>>> >>>>> I have a few questions concerning GAP interface in Sage 7.x. >>>>> >>>>> I have a permutation group G acting on a set S and I would like to >>>>> compute the representatives of the orbits of G acting on k-sets of S. >>>>> >>>>> I recall that a while ago I could do the following (as seen on this >>>>> example >>>>> http://ask.sagemath.org/question/9652/orbits-on-group-actions-acting-on-sets/?answer=14470#post-id-14470 >>>>> ) >>>>> >>>>> ==== >>>>> sage: g=SymmetricGroup(7) >>>>> sage: >>>>> gap("Orbits("+str(g._gap_())+","+str(tuples([1..7],2))+",OnTuples)") >>>>> ==== >>>>> >>>>> and yes, it works in Sage 6.x. However, in Sage 7.x one gets the >>>>> following error >>>>> >>>>> ==== >>>>> TypeError: Gap terminated unexpectedly while reading in a large line: >>>>> Gap produced error output >>>>> Error, Permutation: cycles must be disjoint and duplicate-free >>>>> ==== >>>>> >>>>> Given this, I have the following questions >>>>> >>>>> - What is the proper way to call gap in Sage 7x t obtain the orbits of >>>>> a group G acting on k-sets of a set S? >>>>> - (GAP question) I recall there is a way to return only the >>>>> representatives of the orbits? Anyone happens to recall the right GAP >>>>> command for that? >>>>> - Does it make sense to add an option for various group actions to >>>>> Sage directly (as is already done for specific orbits ) ? >>>>> >>>>> Best, >>>>> >>>>> Jernej >>>>> >>>> -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
