Opened 5 years ago
Closed 4 years ago
#19290 closed defect (wontfix)
MatroidUnion _rank accept any iterator, partition accept empty partition
| Reported by: | chaoxu | Owned by: | |
|---|---|---|---|
| Priority: | trivial | Milestone: | sage-duplicate/invalid/wontfix |
| Component: | matroid theory | Keywords: | |
| Cc: | Stefan, yomcat, Rudi | Merged in: | |
| Authors: | Chao Xu | Reviewers: | |
| Report Upstream: | N/A | Work issues: | |
| Branch: | u/chaoxu/matroid_union (Commits) | Commit: | 4f501fbc5cdc0958d148bfe98b42a3a571a337e5 |
| Dependencies: | Stopgaps: |
Description
Currently, in MatroidUnion? _rank(X) can only accept objects X that we can take the set difference with another frozenset. There are objects having frozenset interface, but cannot be used in taking differences.
The PartitionMatroid? can't handle empty partition.
Change History (6)
comment:1 Changed 5 years ago by
- Branch set to u/chaoxu/matroid_union
comment:2 Changed 5 years ago by
- Commit set to 4f501fbc5cdc0958d148bfe98b42a3a571a337e5
- Status changed from new to needs_review
comment:3 Changed 5 years ago by
- Cc Rudi added
- Component changed from PLEASE CHANGE to matroid theory
Hi Chao,
It is OK if underscored methods like ._rank are picky about the kind of input they can handle. The idea behind having both .rank() and ._rank() is that .rank() should be convenient to use (by checking the input, possibly reformatting it), and ._rank() as efficient as possible (by assuming the input is of the right form).
So unless there is no efficiency hit whatsoever, I don't like the idea of adjusting ._rank to accept more varied input.
comment:4 Changed 5 years ago by
- Status changed from needs_review to needs_work
See http://doc.sagemath.org/html/en/reference/matroids/sage/matroids/matroid.html#sage.matroids.matroid.Matroid for an explanation of what we normally assume about inputs to our underscored functions. I agree with Rudi in this case, it is the responsibility of the caller to provide something with set interface to _rank, not the responsibility of _rank.
In addition, please keep your tickets to one issue per ticket: the PartitionMatroid? fix is fine, but can't go in because of the first issue.
comment:5 Changed 4 years ago by
- Milestone changed from sage-6.9 to sage-duplicate/invalid/wontfix
- Status changed from needs_work to positive_review
The first issue is not a bug; the second issue is now #23213
comment:6 Changed 4 years ago by
- Resolution set to wontfix
- Status changed from positive_review to closed
Closing tickets in the sage-duplicate/invalid/wontfix module with positive_review (i.e. someone has confirmed they should be closed).
New commits:
fix bugs: empty partition. _rank in MatroidUnion accepts any iterator.