Opened 8 years ago
Closed 8 years ago
#18610 closed defect (fixed)
Bug: Circular Descent Check in WeylGroups
Reported by: | nathanwilliams | Owned by: | |
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Priority: | major | Milestone: | sage-6.8 |
Component: | combinatorics | Keywords: | sagedays64.5, coxeter, descent |
Cc: | VivianePons, stumpc5 | Merged in: | |
Authors: | Nathan Williams | Reviewers: | Frédéric Chapoton |
Report Upstream: | N/A | Work issues: | |
Branch: | ab4999f (Commits, GitHub, GitLab) | Commit: | ab4999f27f1e84c2659c544ccc1b5ee3afe7b729 |
Dependencies: | Stopgaps: |
Description (last modified by )
The following code breaks:
WeylGroup(['A',2]).long_element().has_left_descent(1)
Change History (12)
comment:1 Changed 8 years ago by
Authors: | → Nathan Williams |
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Cc: | VivianePons stumpc5 added |
Component: | PLEASE CHANGE → combinatorics |
Description: | modified (diff) |
Keywords: | sagedays64.5 coxeter descent added |
Type: | PLEASE CHANGE → defect |
comment:2 Changed 8 years ago by
comment:3 Changed 8 years ago by
Branch: | → u/nathanwilliams/bug__circular_descent_check_in_weylgroups |
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comment:4 Changed 8 years ago by
Commit: | → 8fe1bb853913ea62a065bf5b53fa460928354815 |
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Status: | new → needs_review |
The suggestion is essentially a good one, but fails because CoxeterGroups().example()
is in a category where this again will cause an infinite loop. Changing has_right_descent(i)
in the way suggested works.
New commits:
5716df5 | Fixed according to Travis's suggestions
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4404133 | Fixed according to Travis's suggestions, and now actually running I think
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8fe1bb8 | Tab fixed
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comment:7 follow-up: 8 Changed 8 years ago by
Status: | needs_review → needs_work |
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I think this really needs to be solved.
Either you go this way, but add a doctest, or you use the other ticket.
comment:8 Changed 8 years ago by
Replying to chapoton:
I think this really needs to be solved.
Either you go this way, but add a doctest, or you use the other ticket.
I had added a test, so could I ask you to be more specific about what you would like?
comment:9 Changed 8 years ago by
Commit: | 8fe1bb853913ea62a065bf5b53fa460928354815 → ab4999f27f1e84c2659c544ccc1b5ee3afe7b729 |
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Branch pushed to git repo; I updated commit sha1. New commits:
ab4999f | more intelligent fix a la stump
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comment:10 Changed 8 years ago by
Status: | needs_work → needs_review |
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comment:11 Changed 8 years ago by
Reviewers: | → Frédéric Chapoton |
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Status: | needs_review → positive_review |
ok, this does not seem to break anything. Let it be
comment:12 Changed 8 years ago by
Branch: | u/nathanwilliams/bug__circular_descent_check_in_weylgroups → ab4999f27f1e84c2659c544ccc1b5ee3afe7b729 |
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Resolution: | → fixed |
Status: | positive_review → closed |
This is because the Weyl group element implements
has_descent
, which is the standard entry point, and the default implementations do the following call structure:since I think most code calls
has_descent
and gives the shortest path function call path if someone only implementshas_left_descent
. So the solution would be to explicitly havehas_left_descent(i)
callhas_descent(i, side='left')
.