#20650: Add is_polynomial and make_look_poly to projective morphism
-------------------------------------+-------------------------------------
Reporter: rlmiller | Owner: rlmiller
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-7.3
Component: algebra | Resolution:
Keywords: | Merged in:
Authors: Rebecca Lauren | Reviewers: Ben Hutz
Miller | Work issues:
Report Upstream: N/A | Commit:
Branch: | 530a5858742e5075485487213645d537a7a865f8
u/bhutz/polynomials | Stopgaps:
Dependencies: |
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Changes (by bhutz):
* status: needs_review => needs_work
* commit: c19032f06179fcb8daae8dda215ce7a639047085 =>
530a5858742e5075485487213645d537a7a865f8
* reviewer: => Ben Hutz
Comment:
I did some code clean-up. No functionality was changed except that instead
of having to compute the inverses of the conjugation it now just computes
the right one to start with.
There are still a few functionality issues: Other base rings that should
work do not such as QQ
{{{
P.<x,y>=ProjectiveSpace(QQ,1)
H=End(P)
f=H([x^2+y^2,y^2])
f.is_polynomial()
}}}
I think it likely these will work for finite fields as well
{{{
P.<x,y>=ProjectiveSpace(GF(13),1)
H=End(P)
f=H([x^2+y^2,y^2])
f.is_polynomial()
}}}
Function field base rings are not going to work, but this error isn't very
informative
{{{
R.<c>=PolynomialRing(QQ)
P.<x,y>=ProjectiveSpace(FractionField(R),1)
H=End(P)
f=H([x^2+c*y^2,y^2])
f.is_polynomial()
}}}
{{{
R.<c>=FunctionField(QQ)
P.<x,y>=ProjectiveSpace(R,1)
H=End(P)
f=H([x^2+c*y^2,y^2])
f.is_polynomial()
}}}
The single rational preimage check is not sufficient
{{{
K.<w>=QuadraticField(4/27)
P.<x,y>=ProjectiveSpace(K,1)
H=End(P)
S=P.coordinate_ring()
f=H([x^3+w*y^3,x*y^2])
f.is_polynomial()
}}}
----
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=530a5858742e5075485487213645d537a7a865f8
530a585]||{{{20650: code clean up}}}||
--
Ticket URL: <http://trac.sagemath.org/ticket/20650#comment:9>
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