Opened 6 years ago

Closed 6 years ago

#15958 closed defect (fixed)

Bug in Partition Algebras

Reported by: Bruce Owned by: Bruce
Priority: minor Milestone: sage-6.2
Component: combinatorics Keywords:
Cc: tscrim, sage-combinat Merged in:
Authors: Bruce Westbury Reviewers: Darij Grinberg, Chwas Ahmed
Report Upstream: N/A Work issues:
Branch: 92d3350 (Commits) Commit: 92d3350ed305fe53fcf4eda491138b32b2bd4278
Dependencies: Stopgaps:

Description

There is a bug in the implementation of the product in partition algebras. 

sage: A = PartitionAlgebra(1,17)
sage: g = SetPartitionsAk(1).list()
sage: a = A[g[1]]
sage: a
P[{{-1}, {1}}]
sage: a*a
P[{{-1}, {1}}]

This should return 

17*P[{{-1}, {1}}]

Change History (16)

comment:1 Changed 6 years ago by Bruce

  • Type changed from PLEASE CHANGE to defect

comment:2 Changed 6 years ago by Bruce

  • Component changed from PLEASE CHANGE to combinatorics

comment:3 Changed 6 years ago by Bruce

  • Branch set to u/Bruce/ticket/15958
  • Created changed from 03/17/14 10:42:04 to 03/17/14 10:42:04
  • Modified changed from 03/17/14 11:43:18 to 03/17/14 11:43:18

comment:4 Changed 6 years ago by git

  • Commit set to 70747fb6fa10db18414a9e49e06f3769c7e17eb0

Branch pushed to git repo; I updated commit sha1. New commits:

​70747fbFixed an error

comment:5 Changed 6 years ago by Bruce

  • Status changed from new to needs_review

comment:6 Changed 6 years ago by darij

  • Branch changed from u/Bruce/ticket/15958 to public/ticket/15958
  • Commit changed from 70747fb6fa10db18414a9e49e06f3769c7e17eb0 to 92d3350ed305fe53fcf4eda491138b32b2bd4278

New commits:

​7866a3aMerge branch 'u/Bruce/ticket/15958' of trac.sagemath.org:sage into 15958
​92d3350add doctests, improve documentation, duplicate the fix in partition_algebra.py
Last edited 6 years ago by darij (previous) (diff)

comment:7 Changed 6 years ago by darij

  • Cc tscrim sage-combinat added

Good catch! I've improved it a bit. First of all, bugs fixed should be doctested to ensure that they don't reappear when someone later copies bad code (or for other reasons). Second, there is no good reason to check for len(part_list) > 0 after a call to part_list[0]; that test should have been removed rather than corrected. (By the way, this was already inside an if len(part_list) > 0 clause...) Finally, the code is (for some reason) duplicated in partition_algebra.py; I don't have the time to track down the reasons of this duplication, but I've fixed the bug over there as well.

Bad news is that someone else will have to review this ticket now. :)

comment:8 Changed 6 years ago by Chwas

  • Owner changed from (none) to Chwas

comment:9 in reply to: ↑ description Changed 6 years ago by Chwas

I think you are right about the bug, and I will try to review it.

Last edited 6 years ago by Chwas (previous) (diff)

comment:10 Changed 6 years ago by darij

Any progress? Hello?

comment:11 Changed 6 years ago by Chwas

  • Owner changed from Chwas to (none)

comment:12 Changed 6 years ago by Chwas

  • Status changed from needs_review to positive_review

comment:13 Changed 6 years ago by tscrim

  • Authors set to Bruce Westbury
  • Owner changed from (none) to Bruce
  • Reviewers set to Darij Grinberg,

Chwas, please add your real name to the reviewers.

comment:14 Changed 6 years ago by Chwas

  • Reviewers changed from Darij Grinberg, to Darij Grinberg, Chwas

comment:15 Changed 6 years ago by Chwas

  • Reviewers changed from Darij Grinberg, Chwas to Darij Grinberg, Chwas Ahmed

comment:16 Changed 6 years ago by vbraun

  • Branch changed from public/ticket/15958 to 92d3350ed305fe53fcf4eda491138b32b2bd4278
  • Resolution set to fixed
  • Status changed from positive_review to closed
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