> I think a main reference is "Permutation Group Algorithms" by Akos > Seress - Cambridge Tracts in Mathemathics 152 published 2003.
Thanks! The "Handbook of computational group theory" also looks like serious business. Unfortunately, neither of these is a free resource; I might end up buying one, I don't know. > I worked as a student last year and may apply as mentor this year. > Please take a look at my branches in github. I was implementing the > Schreier Sims algorithm but I ran out of time unfortunately. You could > either help me merge my branches in or take off where I left. OK, I'll hopefully have the time to take a look this coming week. > Is this necessary? All groups are isomorphic to the permutation group > anyway. Groups for specific structures can make use of functionality > implemented for them (matrix group -> sympy matrices, galois -> polys) > for basic operations and can implement the mapping to the perm group > module for group theoretic operations. So I looked at the permutations module and it has a lot of nice group- ish functions (like composing/inverting permutations, raising to powers, conjugating permutations, getting the order (as an element of the corresponding symmetric group) of a permutation, ...). These can be incorporated in a representation of groups using permutation groups; Galois groups would fit perfectly in this representation since they naturally live inside the symmetric groups, and yes a lot of the functions in the polys module will be helpful. Also, there are generators for common groups like S_n, C_n, D_n, A_n in the context of permutation representations. All this provides a nice foundation for defining a Group class or something like that, with one of the ways of representing it being the permutation representation. Other ways (e.g., matrices, character tables, list of generators and relations) could probably be added later, and functionality to go from one to representation to another? In other news, I found a bug inside the generators.py file in the permutations module - the dihedral group D_2 of order 4 is given a wrong permutation representation. I have a fix for this (well it's quite straightforward, just manually considering the case n=2 and outputting the right representation, because the general algorithm fails there), what should I do about it? Aleksandar Makelov -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
