Opened 9 years ago
Closed 7 years ago
#13248 closed enhancement (fixed)
Coxeter groups: all elements of length N, random elements
Reported by:  sdenton  Owned by:  joyner 

Priority:  minor  Milestone:  sage6.3 
Component:  group theory  Keywords:  sd40, coxeter 
Cc:  nthiery, heglin, tscrim, darij  Merged in:  
Authors:  Tom Denton, Frédéric Chapoton  Reviewers:  Mike Zabrocki, Travis Scrimshaw 
Report Upstream:  N/A  Work issues:  
Branch:  a96be6f (Commits)  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 9 years ago by
 Keywords sd40 added
comment:2 Changed 7 years ago by
 Milestone changed from sage5.11 to sage5.12
comment:3 Changed 7 years ago by
 Milestone changed from sage6.1 to sage6.2
comment:4 Changed 7 years ago by
 Keywords coxeter added
comment:5 Changed 7 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:6 Changed 7 years ago by
Maybe we should then move the code to Coxeter groups, it it works.
comment:7 Changed 7 years ago by
 Branch set to u/chapoton/13248
 Commit set to 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 7 years ago by
 Commit changed from c2ce1c2aadf83f0e4e10ec2ac307286ac5ecbd1f to 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 7 years ago by
 Cc nthiery added; ntiery removed
comment:10 Changed 7 years ago by
 Milestone changed from sage6.2 to sage6.3
comment:11 Changed 7 years ago by
 Description modified (diff)
 Status changed from new to needs_review
 Work issues set to random not yet done
comment:12 Changed 7 years ago by
 Commit changed from 93faac6d489a6b3a54ff5573e90444290bcced8c to a94f96885688a39006c58fceb041694a2716b372
comment:13 Changed 7 years ago by
 Commit changed from a94f96885688a39006c58fceb041694a2716b372 to fb613e237c7fb1785256f33fe115d7890c6120bb
Branch pushed to git repo; I updated commit sha1. New commits:
fb613e2  trac #13248 remove code duplication

comment:14 Changed 7 years ago by
 Work issues random not yet done deleted
comment:15 Changed 7 years ago by
 Cc tscrim darij added
 Reviewers changed from zabrocki to Mike Zabrocki
ping ?
comment:16 Changed 7 years ago by
 Branch changed from u/chapoton/13248 to u/tscrim/13248
 Commit changed from fb613e237c7fb1785256f33fe115d7890c6120bb to 707c9c39ec02ba112f19e614a26c99e430b7bd67
 Reviewers changed from Mike Zabrocki to 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 7 years ago by
 Branch changed from u/tscrim/13248 to u/chapoton/13248
 Commit changed from 707c9c39ec02ba112f19e614a26c99e430b7bd67 to a96be6f6bbe8a90d811570c5023620955e82cce7
 Status changed from needs_review to 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 7 years ago by
 Branch changed from u/chapoton/13248 to a96be6f6bbe8a90d811570c5023620955e82cce7
 Resolution set to fixed
 Status changed from positive_review to closed
Where is the code ?