#11930: disallow non-smooth hyperelliptic curves, and let hyperelliptic curves
know
they are not singular
-------------------------------------------------------------+--------------
Reporter: dkrenn | Owner:
cremona
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-5.0
Component: elliptic curves | Resolution:
Keywords: hyperelliptic curve singular smooth sd35 | Work issues:
Report Upstream: N/A | Reviewers:
Marco Streng, Damiano Testa, David Eklund
Authors: Daniel Krenn, Marco Streng, Damiano Testa | Merged in:
Dependencies: | Stopgaps:
-------------------------------------------------------------+--------------
Description changed by mstreng:
Old description:
> Hyperelliptic curves are smooth curves mathematically. These patches add
> a check for this to the constructor and implement {{{is_singular}}} to
> always return {{{False}}}
>
> Example
> {{{
> sage: R.<x> = PolynomialRing(GF(3))
> sage: H=HyperellipticCurve(x^5+1)
> sage: H.is_singular()
> # used to return True, now returns False
> sage: H=HyperellipticCurve(x^5)
> # used to return a curve y^2 = x^5, now raises an error
> }}}
>
> Apply
>
> * [attachment:11930c.patch]
> * [attachment:11930_is_singular.patch]
New description:
Hyperelliptic curves are smooth curves mathematically. These patches add a
check for this to the constructor and implement {{{is_singular}}} to
always return {{{False}}}
Example
{{{
sage: R.<x> = PolynomialRing(GF(3))
sage: H=HyperellipticCurve(x^5+1)
sage: H.is_singular()
# used to return True, now returns False
sage: H.is_smooth()
# used to return False, now returns True
sage: HyperellipticCurve(x^5)
# used to return a curve y^2 = x^5, now raises an error
}}}
Apply
* [attachment:11930c.patch]
* [attachment:11930_is_singular2.patch]
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11930#comment:25>
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