Opened 9 years ago
Closed 8 years ago
#15672 closed defect (fixed)
Computing degree bound GBs with Magma is broken
Reported by: | malb | Owned by: | |
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Priority: | minor | Milestone: | sage-6.4 |
Component: | interfaces | Keywords: | magma, sd59 |
Cc: | Bouillaguet | Merged in: | |
Authors: | Martin Albrecht | Reviewers: | Jakob Kroeker |
Report Upstream: | None of the above - read trac for reasoning. | Work issues: | |
Branch: | 7e43991 (Commits, GitHub, GitLab) | Commit: | 7e43991bb20fd075881d3bf8679cd756d0a91515 |
Dependencies: | Stopgaps: |
Description
This should work:
sage: R.<a,b,c,d,e,f,g,h,i,j> = PolynomialRing(GF(127),10) sage: I = sage.rings.ideal.Cyclic(R,6) sage: gb = I.groebner_basis('magma:GroebnerBasis', deg_bound=4)
The culprit is that PolynomialSequence casts to an ideal in Magma, but we need a sequence.
Change History (16)
comment:1 Changed 9 years ago by
Commit: | → 0f45e69a440d47b7476be3a9fe3c16b766f22451 |
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comment:2 Changed 9 years ago by
Status: | new → needs_review |
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comment:3 Changed 9 years ago by
Milestone: | sage-6.1 → sage-6.2 |
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comment:4 Changed 9 years ago by
Milestone: | sage-6.2 → sage-6.3 |
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comment:6 Changed 9 years ago by
Keywords: | sd59 added |
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comment:8 Changed 9 years ago by
Status: | needs_review → needs_info |
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I get a different ouput for gb
,
so the doctest fails for me at len(gb)
sage: R.<a,b,c,d,e,f,g,h,i,j> = PolynomialRing(GF(127),10) sage: I = sage.rings.ideal.Cyclic(R,6) sage: gb = I.groebner_basis('magma:GroebnerBasis', deg_bound=4) sage: len(gb) # optional - magma 7 # doctest expects 5
Singular tells me 7, too (but we should not rely on that)
So why in your output len(gb) =5 ? I have access to a dated magma version 2.17-8
.
Here is the gb output I get:
[a*b*c*d*e*f - 1, a*b*c*d*e - 3*b*c*d*e*f - c^2*d*e*f - 2*c*d^2*e*f - 2*c*d*e^2*f - d^2*e^2*f + b*c*d*f^2 + 2*b*c*e*f^2 + 2*b*d*e*f^2 + 3*c*d*e*f^2 + 2*d^2*e*f^2 + b*e^2*f^2 + c*e^2*f^2 + 3*d*e^2*f^2 + e^3*f^2 - b*c*f^3 - c*d*f^3 - 3*b*e*f^3 - 3*c*e*f^3 - d*e*f^3 + b*f^4 + c*f^4 + d*f^4 - 3*e*f^4 + f^5, c^3*d - c^2*d^2 + b*c*d*e + 2*c^2*d*e - 2*c*d^2*e - c^3*f - b*c*d*f + 3*c^2*d*f + 2*c*d^2*f - c^2*e*f + b*e^2*f + c*e^2*f + d*e^2*f + e^3*f - b*c*f^2 - 4*c^2*f^2 - b*d*f^2 - d^2*f^2 + 4*b*e*f^2 + 2*c*e*f^2 + 2*d*e*f^2 + 5*e^2*f^2 - 3*b*f^3 - 6*c*f^3 - 4*d*f^3 + 3*e*f^3 - 3*f^4, b*c*d^2 - b*c*d*e + c*d^2*e - c*d^2*f + b*c*e*f + c*d*e*f + d*e^2*f - b*c*f^2 + b*d*f^2 + d^2*f^2 - 2*b*e*f^2 - 2*c*e*f^2 - 2*d*e*f^2 - e^2*f^2 + b*f^3 + c*f^3 + 2*d*f^3 - 2*e*f^3 + f^4, b*c^2 - b*c*d + c^2*d - c^2*f + b*e*f + c*e*f + d*e*f + e^2*f - b*f^2 - 2*c*f^2 - d*f^2 + e*f^2 - f^3, b^2 + b*d - c*d + b*e - d*e + 2*b*f + c*f + d*f + f^2, a + b + c + d + e + f]
comment:9 Changed 9 years ago by
Commit: | 0f45e69a440d47b7476be3a9fe3c16b766f22451 → 7e43991bb20fd075881d3bf8679cd756d0a91515 |
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comment:10 Changed 9 years ago by
Status: | needs_info → needs_review |
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I checked with my Magma install and indeed 5 was wrong. It also returns 7. I've fixed the doctest.
comment:11 Changed 9 years ago by
Status: | needs_review → positive_review |
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comment:13 Changed 8 years ago by
Milestone: | sage-6.3 → sage-6.4 |
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comment:14 Changed 8 years ago by
Reviewers: | → Jakob Kroeker |
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Status: | needs_work → needs_review |
comment:15 Changed 8 years ago by
Status: | needs_review → positive_review |
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comment:16 Changed 8 years ago by
Branch: | u/malb/magma_gb_deg_bound → 7e43991bb20fd075881d3bf8679cd756d0a91515 |
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Resolution: | → fixed |
Status: | positive_review → closed |
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Branch pushed to git repo; I updated commit sha1. New commits:
fix deg_bound=someint when algorithm='magma' in Gröbner basis computations