Ticket #13671 (closed defect: fixed)
p.lift(...) results are non-deterministic and incoherent for multivariate polynomials
| Reported by: | Bouillaguet | Owned by: | malb |
|---|---|---|---|
| Priority: | major | Milestone: | sage-5.5 |
| Component: | commutative algebra | Keywords: | polynomial rings, mathematically wrong result |
| Cc: | mstreng, malb | Work issues: | |
| Report Upstream: | N/A | Reviewers: | Marco Streng |
| Authors: | Charles Bouillaguet | Merged in: | sage-5.5.beta2 |
| Dependencies: | Stopgaps: |
Description (last modified by mstreng) (diff)
Merge together with #13675, circular dependency
sage: R.<x1,x2> = QQ[] sage: I = R.ideal(x2**2 + x1 - 2, x1**2 - 1) sage: test = I.gen(0) + x2*I.gen(1) sage: test.lift(I) # correct [1, x2] sage: (test+1).lift(I) # invalid input, should give error [0, 0] sage: test.lift(I) # incorrect [0, 0]
p.lift(I) should raise an exception "ValueError: polynomial is not in the ideal" instead of returning [0,0,...,0] in the first place...
Merge together with #13675, circular dependency
Attachments
-
13671_lift_bug.patch
(2.5 KB) -
added by Bouillaguet 7 months ago.
- Apparently fixing the bug
Change History
comment:2 Changed 7 months ago by Bouillaguet
- Status changed from new to needs_review
- Authors set to Charles Bouillaguet
comment:3 Changed 7 months ago by mstreng
- Status changed from needs_review to needs_work
Did you ask Gauss to write the patch for you?
# HG changeset patch # User Carl Friedrich Gauss <cfgauss@uni-goettingen.de>
You should update the .hmrc file in your home directory (use your own name and email address) and export a new patch here and at #13675.
comment:4 follow-up: ↓ 5 Changed 7 months ago by mstreng
ps. Would it be possible to add a check which error was reported by Singular? Just in case self is in I, but Singular reports an error for some other reason (in which case I guess RuntimeError is appropriate).
comment:5 in reply to: ↑ 4 Changed 7 months ago by Bouillaguet
- Status changed from needs_work to needs_review
Replying to mstreng:
ps. Would it be possible to add a check which error was reported by Singular? Just in case self is in I, but Singular reports an error for some other reason (in which case I guess RuntimeError is appropriate).
I renamed myself and tested that Singular returns 1 when the polynomial is not in the ideal...
comment:6 follow-up: ↓ 7 Changed 7 months ago by mstreng
4088 errorreported = 0 4089 if errorreported == 1:
This looks like it does not work.
comment:7 in reply to: ↑ 6 Changed 7 months ago by Bouillaguet
Replying to mstreng:
4088 errorreported = 0 4089 if errorreported == 1:This looks like it does not work.
Good lord, that was stupid.
comment:8 follow-up: ↓ 9 Changed 7 months ago by mstreng
- Status changed from needs_review to positive_review
- Reviewers set to Marco Streng
- Description modified (diff)
Looks good!
comment:10 in reply to: ↑ 9 Changed 7 months ago by mstreng
Replying to Bouillaguet:
I don't understand the circular dependency... Why would this one depend on #13675 ?
Not all doctests pass when only this patch is applied.
comment:11 Changed 6 months ago by jdemeyer
- Status changed from positive_review to closed
- Resolution set to fixed
- Merged in set to sage-5.5.beta2
Hans (of Singular) wrote:
This could be it, we don't reset it.