#16926: Merge the features of SymmetricGroupAlgebra and SymmetricGroup.algebra
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Reporter: nthiery | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/combinat/fix_sga-16926 | 6597e7936048b8f30018a5e4a6e566836f6e5e68
Dependencies: | Stopgaps:
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Comment (by tscrim):
Replying to [comment:16 darij]:
> Not sure if I'm going to be reviewing this (time is short as usual and
I'm still not good at OOP -- case in point, I don't know what mixins are
for), but a few remarks.
I appreciate any time you can devote, plus I'd think it would be best that
Nicolas takes a good look at this patch (and possibly have Aladin merge it
into his current version of #11111 and test it there too).
(Mixins are as they sound to be, they are classes you "mix in" the class
heirarchy which typically contain general or independent features.
[[http://stackoverflow.com/questions/533631/what-is-a-mixin-and-why-are-
they-useful|This SO thread]] I think gives a good overview of them.)
> First, a trivial group needs no generators. ...
Good point; fixed.
> Second, you are testing for the order-of-multiplication global in
`has_left_descent` and in `has_right_descent`. I understand the reasoning
behind it, but I don't like it, as it spreads a bad design choice further.
Can we agree that the "left" in "left descent" stands for "left action"
rather than "multiplying with s_i from the left", or is this too
revisionistic?
It breaks the generic implementation of the `long_element` method, which
relies on the multiplication on the left corresponding to
`has_left_descent`. I feel these changes further shows `permutation.py`
can be a minefield...but I'm trying to make do with what I have.
--
Ticket URL: <http://trac.sagemath.org/ticket/16926#comment:18>
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