#15454: Implement Eulerian (quasi)symmetric functions
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Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.0
Component: combinatorics | Resolution:
Keywords: Eulerian sf, qsym | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/combinat/sf/eulerian | cd66c6470765cc3651553d8af9dde2d99ab76962
Dependencies: | Stopgaps:
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Comment (by tscrim):
Replying to [comment:3 darij]:
> Interesting -- these were new to me, despite the paper being in my
algebra folder...
>
> What is the rationale behind replacing
`sage.combinat.partition.Partitions()` by `_Partitions`? Speed? (And why
only sometimes?)
This was something introduced in #13605 since the set of all partitions is
used all over the place and the UniqueRepr. calls do have some effect on
speed. Plus this means it's never garbage collected.
> EDIT: "permtutation", "excedences". Ok, the latter might need some
explanation. Dictionaries say that "exceedences" and "exceedance" are both
right, the latter form apparently being the standard one.
Combinatorialists seem to use either "exceedance" or "excedance". Noone
seems to use "excedence".
Hmmm...curious. I followed what is in `permutation.py`: the method
`weak_excedences()`. Since this is just in the docstring, I think it'd be
okay to use "excedance" to match the reference.
> EDIT2: I find this ambiguous: ``i` is a descent and `i` is not an
excedence or `i + 1` is,`.
That was the least ambiguous way I could come up with. The parenthesis
should be around the "or" but English syntax doesn't allow that. Oh,
here's a thought:
{{{`i` is a descent, and given that `i` is not an excedance or `i + 1`
is,}}}
And because I can't resist the (bad) pun: English is not a language
decided around around logic.
--
Ticket URL: <http://trac.sagemath.org/ticket/15454#comment:4>
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