Opened 10 years ago
Closed 8 years ago
#13248 closed enhancement (fixed)
Coxeter groups: all elements of length N, random elements
Reported by:  tom denton  Owned by:  joyner 

Priority:  minor  Milestone:  sage6.3 
Component:  group theory  Keywords:  sd40, coxeter 
Cc:  Nicolas M. Thiéry, heglin, Travis Scrimshaw, Darij Grinberg  Merged in:  
Authors:  Tom Denton, Frédéric Chapoton  Reviewers:  Mike Zabrocki, Travis Scrimshaw 
Report Upstream:  N/A  Work issues:  
Branch:  a96be6f (Commits, GitHub, GitLab)  Commit:  a96be6f6bbe8a90d811570c5023620955e82cce7 
Dependencies:  Stopgaps: 
Description (last modified by )
Two commonly desired constructions in a Coxeter group are to: a) Iterate over all elements of a given length  this happens especially in affine or other infinite coxeter groups in order to test hypotheses, construct homogenous elements, etc... b) Choose a random element, possibly with length specified. This often occurs to see if a nonspecial element has a given property.
Iterating over all elements of a given length in particular has a nice solution (due to N. Thiery) and anecdotally has been implemented (usually in an inelegant fashion) by numerous community members in response to shortterm problems.
We provide some code implementing these functions!
Change History (18)
comment:1 Changed 10 years ago by
Keywords:  sd40 added 

comment:2 Changed 9 years ago by
Milestone:  sage5.11 → sage5.12 

comment:3 Changed 9 years ago by
Milestone:  sage6.1 → sage6.2 

comment:4 Changed 9 years ago by
Keywords:  coxeter added 

comment:5 Changed 9 years ago by
That's strange; I'm not sure why it isn't there.
The code should be the same used in the AffinePermutationGroup
for the methods elements_of_length
and random_element
.
Example:
sage: A=AffinePermutationGroup?(['A',4,1])
sage: len(list(A.elements_of_length(1)))
5
sage: A.random_element(4)
Type A affine permutation with window [0, 4, 3, 2, 6]
comment:7 Changed 9 years ago by
Branch:  → u/chapoton/13248 

Commit:  → c2ce1c2aadf83f0e4e10ec2ac307286ac5ecbd1f 
here is a git branch, moving elements_of_length into the category of coxeter groups
New commits:
c2ce1c2  trac #13248 first step : moving elements_of_length to coxeter groups

comment:8 Changed 8 years ago by
Commit:  c2ce1c2aadf83f0e4e10ec2ac307286ac5ecbd1f → 93faac6d489a6b3a54ff5573e90444290bcced8c 

Branch pushed to git repo; I updated commit sha1. New commits:
93faac6  Merge branch 'u/chapoton/13248' of trac.sagemath.org:sage into 13248

comment:9 Changed 8 years ago by
Cc:  Nicolas M. Thiéry added; ntiery removed 

comment:10 Changed 8 years ago by
Milestone:  sage6.2 → sage6.3 

comment:11 Changed 8 years ago by
Description:  modified (diff) 

Status:  new → needs_review 
Work issues:  → random not yet done 
comment:12 Changed 8 years ago by
Commit:  93faac6d489a6b3a54ff5573e90444290bcced8c → a94f96885688a39006c58fceb041694a2716b372 

comment:13 Changed 8 years ago by
Commit:  a94f96885688a39006c58fceb041694a2716b372 → fb613e237c7fb1785256f33fe115d7890c6120bb 

Branch pushed to git repo; I updated commit sha1. New commits:
fb613e2  trac #13248 remove code duplication

comment:14 Changed 8 years ago by
Work issues:  random not yet done 

comment:15 Changed 8 years ago by
Authors:  sdenton → Tom Denton, Frédéric Chapoton 

Cc:  Travis Scrimshaw Darij Grinberg added 
Reviewers:  zabrocki → Mike Zabrocki 
ping ?
comment:16 Changed 8 years ago by
Branch:  u/chapoton/13248 → u/tscrim/13248 

Commit:  fb613e237c7fb1785256f33fe115d7890c6120bb → 707c9c39ec02ba112f19e614a26c99e430b7bd67 
Reviewers:  Mike Zabrocki → Mike Zabrocki, Travis Scrimshaw 
Hey Frederic,
I've done some minor tweaks and made it so that random_element
chooses the length at random in [0, 1000]
(so the word is not too long) if not specified. LGTM otherwise, so if you're happy with my changes, then positive review.
New commits:
ec5652c  Merge branch 'u/chapoton/13248' of trac.sagemath.org:sage into u/tscrim/13248

707c9c3  Some review tweaks.

comment:17 Changed 8 years ago by
Branch:  u/tscrim/13248 → u/chapoton/13248 

Commit:  707c9c39ec02ba112f19e614a26c99e430b7bd67 → a96be6f6bbe8a90d811570c5023620955e82cce7 
Status:  needs_review → positive_review 
Hello, and thanks.
I just corrected a typo in "chosen".
I'm setting this to positive review.
New commits:
a96be6f  trac #13248 just corrected a typo in "chosen"

comment:18 Changed 8 years ago by
Branch:  u/chapoton/13248 → a96be6f6bbe8a90d811570c5023620955e82cce7 

Resolution:  → fixed 
Status:  positive_review → closed 
Where is the code ?