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:  sage7.4 
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: 
Description
it already exists for symmetric groups, let us provide a general implementation
Change History (16)
comment:1 Changed 5 years ago by
 Branch set to u/chapoton/21551
 Commit set to f68927a05d9f5bf5f7921deaf9447ed2695df901
 Status changed from new to needs_review
comment:2 Changed 5 years ago by
 Commit changed from f68927a05d9f5bf5f7921deaf9447ed2695df901 to 1949c8e8f0ab44ede687d9b7faa865b83705b69b
Branch pushed to git repo; I updated commit sha1. New commits:
1949c8e  trac 21551 adding a crossreference, some details

comment:3 Changed 5 years ago by
 Cc tscrim added
comment:4 Changed 5 years ago by
Is cov_down_subgroup
short for something?
comment:5 Changed 5 years ago by
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
Maybe also make that an hidden method ?
comment:7 Changed 5 years ago by
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
 Commit changed from 1949c8e8f0ab44ede687d9b7faa865b83705b69b to 116f7eb498c3311ff22764a7f86ebe6040579efb
Branch pushed to git repo; I updated commit sha1. New commits:
116f7eb  trac 21551 reviewer's suggestions

comment:9 Changed 5 years ago by
done. I have chosen to do the lift in "covered_reflections_subgroup".
comment:10 Changed 5 years ago by
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
 Commit changed from 116f7eb498c3311ff22764a7f86ebe6040579efb to 17759737a94a3577424932a9bc3e40118c46782a
Branch pushed to git repo; I updated commit sha1. New commits:
1775973  trac 21551 now as a subgroup

comment:12 Changed 5 years ago by
ok, done
comment:14 Changed 5 years ago by
 Status changed from positive_review to needs_work
Reviewer name...
comment:15 Changed 5 years ago by
 Reviewers set to Travis Scrimshaw
 Status changed from needs_work to positive_review
comment:16 Changed 5 years ago by
 Branch changed from u/chapoton/21551 to 17759737a94a3577424932a9bc3e40118c46782a
 Resolution set to fixed
 Status changed from positive_review to closed
New commits:
implementation of shard order for finite Coxeter groups