William Stein wrote: > On Fri, 02 Nov 2007 09:24:53 -0700, <[EMAIL PROTECTED]> wrote: >>> I guess I just don't think permutation (which are functions) should >>> act on the left. It's repulsive to me. I guess there's just >>> not much more to say than that. >> Ok. I don't think that's a very good attitude to enforce, since a lotof >> people do use left action. > >> Use __call__ for left, and __pow__ for the right. > > I certainly agree with that. > > I'm OK with the code going in. I don't like it at all, but that's fine. I > don't have > to like everything in Sage.
It sounds like the question of notation has already been hashed out (satisfactorily to me, anyway). It might be good to mention here that a permutation already acts on a multivariate polynomial with slightly different notation than suggested above, as given in the doctests in permgroup_element.py (in 2.8.10): sage: G = PermutationGroup(['(1,2,3)(4,5)', '(1,2,3,4,5)']) sage: R.<x,y,z,u,v> = MPolynomialRing(QQ,5) sage: f = x^2 + y^2 - z^2 + 2*u^2 sage: sigma, tau = G.gens() sage: f*sigma -x^2 + y^2 + z^2 + 2*v^2 sage: f*tau y^2 + z^2 - u^2 + 2*v^2 sage: f*(sigma*tau) 2*x^2 - y^2 + z^2 + u^2 sage: (f*sigma)*tau 2*x^2 - y^2 + z^2 + u^2 (notice that it isn't f^sigma, but f*sigma) -Jason P.S. The suggestion originally came up when looking at the graph relabel function, which relabels the vertices of a graph according to a permutation. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
