On 2014-09-05, Viviane Pons <vivianep...@gmail.com> wrote: > The Permutation0 might be a good idea, I don't know... It wouldn't change > the tuple vs. list thing which is used to distinguish between the cycle > notation and the word notation. > > I agree some of the syntax could be improved. But I do think backward > compatibility is important. It's really annoying when you have to rewrite > ALL your old personal code when you update your sage version (which happens > all the time), and I know it's a put-off for many people (and Sage has > quite a bad reputation for it). > > Also, Nathann, please do not assume that you represent all the Sage coders. > I'm a Sage coder and user, and I use 1-Permutation. I use them ALL THE TIME > and I need them. In every single of my programs, because permutation is my > main object of study! And the users you seem to so easily ignore are > contributors too. They contribute to algorithms and maps on permutations > that are useful to everyone. The fact is that in the math world, in every > single paper about the symmetric group, the permutations are 1-Permutations > and it makes sense to have them.
This is not 100% true. In permutation groups one often does not care about the ordering of the domain the group operates on. Besides, if one's domain is, say, Z/nZ, it's immediately obvious that using 0-base is much more natural. It's true that GAP and Magma, historically the oldest GAS' to do permutation groups, number permutations from 1, but this is due to them orginating from a Fortran IV program! Subsequent literature naturally used the same notation, for obvious reasons. So yes, we're captives of Fortran IV here... By the way, I help maintaining some 25+ years old C program to compute with centraliser rings of permutation groups, and there permutations are 0-based: https://github.com/dimpase/coco (it's a rewrite from scratch of a Fortran program, where permutations, naturally, were 1-based :-)) Dima -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
