Opened 5 weeks ago

Last modified 4 weeks ago

#27479 needs_review defect

Univariate PolynomialRing with 'negdegrevlex' order does not get 'ds' order in Singular

Reported by: rburing Owned by:
Priority: major Milestone: sage-8.8
Component: interfaces Keywords: PolynomialRing, Singular, order
Cc: Merged in:
Authors: Ricardo Buring Reviewers:
Report Upstream: N/A Work issues:
Branch: u/rburing/MPolynomialRing_libsingular_univariate_allow_other_monomial_orderings (Commits) Commit: ef6964686b4e5f703817d3a82d01aa26c4f50280
Dependencies: Stopgaps:

Description (last modified by rburing)

Using _singular_init_() univariate polynomial rings get global monomial ordering lp no matter what:

sage: R.<x> = PolynomialRing(QQ, 1, order='negdegrevlex')
sage: R._singular_init_()
polynomial ring, over a field, global ordering
// coefficients: QQ
// number of vars : 1
//        block   1 : ordering lp
//                  : names    x
//        block   2 : ordering C

Contrast with multivariate:

sage: S.<y,z> = PolynomialRing(QQ, 2, order='negdegrevlex')
sage: S._singular_init_()
polynomial ring, over a field, local ordering
// coefficients: QQ
// number of vars : 2
//        block   1 : ordering ds
//                  : names    y z
//        block   2 : ordering C

As long as neg* orders are allowed (see #10708) this should be fixed (and it seems easy to fix).

This is also the cause of a bug in multiplicity() for subschemes of the affine line:

sage: A1.<x> = AffineSpace(QQ,1)
sage: X = A1.subscheme([x^1789+x])
sage: Q = X([0])
sage: X.multiplicity(Q)
1789

as reported in Ask SageMath question #45777.

Change History (5)

comment:1 Changed 5 weeks ago by rburing

  • Description modified (diff)

comment:2 Changed 5 weeks ago by rburing

  • Description modified (diff)

comment:3 Changed 5 weeks ago by rburing

  • Branch set to u/rburing/MPolynomialRing_libsingular_univariate_allow_other_monomial_orderings

comment:4 Changed 5 weeks ago by rburing

  • Authors set to Ricardo Buring
  • Commit set to ef6964686b4e5f703817d3a82d01aa26c4f50280
  • Status changed from new to needs_review

New commits:

ef69646Trac #27479: Allow monomial ordering != 'lp' for univariate MPolynomialRing_libsingular

comment:5 Changed 4 weeks ago by embray

  • Milestone changed from sage-8.7 to sage-8.8

Ticket retargeted after milestone closed (if you don't believe this ticket is appropriate for the Sage 8.8 release please retarget manually)

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