Opened 2 years ago
Closed 23 months ago
#29808 closed defect (fixed)
fix left and right actions of permutations on matrices
Reported by: | gh-mwageringel | Owned by: | |
---|---|---|---|
Priority: | minor | Milestone: | sage-9.2 |
Component: | group theory | Keywords: | |
Cc: | tscrim | Merged in: | |
Authors: | Markus Wageringel | Reviewers: | Travis Scrimshaw |
Report Upstream: | N/A | Work issues: | |
Branch: | a9dd308 (Commits, GitHub, GitLab) | Commit: | a9dd3081e05e858e9a19dca973d51968130ec2db |
Dependencies: | Stopgaps: |
Description
As observed in #29553, permutations incorrectly act on matrices via a left action on the rows when multiplying on the right. This ticket fixes the left action to act on the left, and also adds the missing right action on the columns.
sage: S = SymmetricGroup(6) sage: p, q = S('(1,2,3,4,5,6)'), S('(1,2)(3,4)(5,6)') sage: M = matrix.diagonal([1..6]) sage: (M * p.matrix()) * q.matrix() == M * (p.matrix() * q.matrix()) # correct True sage: (M * p) * q == M * (p * q) # should be True False
Change History (3)
comment:1 Changed 2 years ago by
- Branch set to u/gh-mwageringel/29808
- Cc tscrim added
- Commit set to a9dd3081e05e858e9a19dca973d51968130ec2db
- Status changed from new to needs_review
comment:2 Changed 2 years ago by
- Reviewers set to Travis Scrimshaw
- Status changed from needs_review to positive_review
LGTM.
comment:3 Changed 23 months ago by
- Branch changed from u/gh-mwageringel/29808 to a9dd3081e05e858e9a19dca973d51968130ec2db
- Resolution set to fixed
- Status changed from positive_review to closed
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29808: fix left/right permutation actions on matrices