Opened 5 years ago

Closed 5 years ago

#21551 closed enhancement (fixed)

implement shard order for W finite Coxeter group

Reported by: chapoton Owned by:
Priority: major Milestone: sage-7.4
Component: combinatorics Keywords:
Cc: tscrim Merged in:
Authors: Frédéric Chapoton Reviewers: Travis Scrimshaw
Report Upstream: N/A Work issues:
Branch: 1775973 (Commits, GitHub, GitLab) Commit: 17759737a94a3577424932a9bc3e40118c46782a
Dependencies: Stopgaps:

Status badges

Description

it already exists for symmetric groups, let us provide a general implementation

Change History (16)

comment:1 Changed 5 years ago by chapoton

  • Branch set to u/chapoton/21551
  • Commit set to f68927a05d9f5bf5f7921deaf9447ed2695df901
  • Status changed from new to needs_review

New commits:

f68927aimplementation of shard order for finite Coxeter groups

comment:2 Changed 5 years ago by git

  • Commit changed from f68927a05d9f5bf5f7921deaf9447ed2695df901 to 1949c8e8f0ab44ede687d9b7faa865b83705b69b

Branch pushed to git repo; I updated commit sha1. New commits:

1949c8etrac 21551 adding a cross-reference, some details

comment:3 Changed 5 years ago by tscrim

  • Cc tscrim added

comment:4 Changed 5 years ago by tscrim

Is cov_down_subgroup short for something?

comment:5 Changed 5 years ago by chapoton

Hello Travis.

Indeed, one should choose a better name. This is just a notation with Cov and downarrow, in the "What the Fuss" reference. One could call that "subgroup_generated_by_conjugates_of_right_descents" or something in the same spirit..

comment:6 Changed 5 years ago by chapoton

Maybe also make that an hidden method ?

comment:7 Changed 5 years ago by tscrim

In "Why the Fuss," it is called "covered reflections," so how about covered_reflections_subgroup? Also, it is a natural construction, so it should not be hidden. Yet, I think it should return the submonoid and then the shard_poset should convert it to a frozenset.

Also the arXiv number is missing a 0: 1503.00710.

comment:8 Changed 5 years ago by git

  • Commit changed from 1949c8e8f0ab44ede687d9b7faa865b83705b69b to 116f7eb498c3311ff22764a7f86ebe6040579efb

Branch pushed to git repo; I updated commit sha1. New commits:

116f7ebtrac 21551 reviewer's suggestions

comment:9 Changed 5 years ago by chapoton

done. I have chosen to do the lift in "covered_reflections_subgroup".

comment:10 Changed 5 years ago by tscrim

I am less convinced of returning a list for covered_reflections_subgroup; the submonoid (which knows it is a subgroup) seems like the correct object to return given the method name.

comment:11 Changed 5 years ago by git

  • Commit changed from 116f7eb498c3311ff22764a7f86ebe6040579efb to 17759737a94a3577424932a9bc3e40118c46782a

Branch pushed to git repo; I updated commit sha1. New commits:

1775973trac 21551 now as a subgroup

comment:12 Changed 5 years ago by chapoton

ok, done

comment:13 Changed 5 years ago by tscrim

  • Status changed from needs_review to positive_review

Thanks.

comment:14 Changed 5 years ago by vbraun

  • Status changed from positive_review to needs_work

Reviewer name...

comment:15 Changed 5 years ago by tscrim

  • Reviewers set to Travis Scrimshaw
  • Status changed from needs_work to positive_review

comment:16 Changed 5 years ago by vbraun

  • Branch changed from u/chapoton/21551 to 17759737a94a3577424932a9bc3e40118c46782a
  • Resolution set to fixed
  • Status changed from positive_review to closed
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