Opened 11 years ago

Closed 5 years ago

Last modified 5 years ago

#8685 closed defect (worksforme)

evaluation of Monsky-Washnitzer objects

Reported by: jen Owned by: was
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: number theory Keywords: days71
Cc: robertwb, kedlaya, roed, jpflori Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description

The following should raise an error since f0 has a singularity at P (and isn't necessarily 0 at all finite Weierstrass points):

sage: R.<x> = QQ['x']
sage: H= HyperellipticCurve(x^3-10*x+9)
sage: K = Qp(5,10)
sage: HK = H.change_ring(K)
sage: P = HK(1,0)
sage: import sage.schemes.elliptic_curves.monsky_washnitzer as mw
sage: Mfrob,forms=mw.matrix_of_frobenius_hyperelliptic(HK)
sage: f0 = forms[0]
sage: f0(P[0],P[1])
0
sage: f0(x,K(0))
0

In fact, Sage seems to knows this...just not when the y-coordinate is 0 in the p-adic field. So, a coercion error?

sage: f0(x,0)
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)

ZeroDivisionError: Rational division by zero

Change History (12)

comment:1 Changed 11 years ago by kedlaya

  • Cc roed added

This appears to be a problem with (surprise) power series over p-adic fields:

sage: R.<y> = LaurentSeriesRing(Rationals())
sage: K = Qp(5, 10)
sage: u = y^(-1)
sage: u(K(0)) ## Should blow up but doesn't
0
sage: u(0) ## Should blow up and does
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)

ZeroDivisionError: Rational division by zero

comment:2 Changed 8 years ago by jdemeyer

  • Milestone changed from sage-5.11 to sage-5.12

comment:3 Changed 7 years ago by vbraun_spam

  • Milestone changed from sage-6.1 to sage-6.2

comment:4 Changed 7 years ago by vbraun_spam

  • Milestone changed from sage-6.2 to sage-6.3

comment:5 Changed 7 years ago by vbraun_spam

  • Milestone changed from sage-6.3 to sage-6.4

comment:6 Changed 6 years ago by jpflori

  • Cc jpflori added

comment:7 Changed 5 years ago by kedlaya

I just tried the test cases and (modulo the fact that monsky_washnitzer moved to hyperelliptic_curves) they no longer return the claimed errors. Probably this is due to some bug in p-adic power series getting fixed (perhaps #9457).

In light of that, I propose to resolve this ticket as "fixed".

comment:8 Changed 5 years ago by roed

  • Status changed from new to needs_review

comment:9 Changed 5 years ago by roed

  • Status changed from needs_review to positive_review

Works for me.

comment:10 Changed 5 years ago by roed

  • Milestone changed from sage-6.4 to sage-duplicate/invalid/wontfix

comment:11 Changed 5 years ago by vbraun

  • Resolution set to worksforme
  • Status changed from positive_review to closed

comment:12 Changed 5 years ago by jen

  • Keywords days71 added
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