#17282: Implementing Wehler K3 Surfaces
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       Reporter:  jdefaria           |        Owner:
           Type:  enhancement        |       Status:  needs_work
       Priority:  major              |    Milestone:  sage-6.7
      Component:  algebraic          |   Resolution:
  geometry                           |    Merged in:
       Keywords:                     |    Reviewers:  Ben Hutz, Grayson
        Authors:  Joao Alberto de    |  Jorgenson
  Faria                              |  Work issues:
Report Upstream:  N/A                |       Commit:
         Branch:                     |  1edfe71b0fda3685fd3edc0bd9b9e1532d549f28
  u/jdefaria/ticket/17282            |     Stopgaps:
   Dependencies:                     |
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Changes (by bhutz):

 * status:  needs_review => needs_work


Comment:

 Here is what I see in the documentation:

 ramification poly

  * cite call silverman
  * output: polynomial in coordinate ring of ambient space

 canonical height

  * change '-' to 'minus'

 canonical height minus

  * change '+' to 'minus'
  * 'Use v=0 for the archimedean place' should be deleted
  * add (local heights) after 'lambda minus heights'

 canonical height plus

  * - 'Use v=0 for the archimedean place' should be deleted
  * add (local heights) after 'lambda plus heights'

 degenerate fibers

  * Remove the extra 'in' in 'The output is a list of lists where in the
 elements of lists are points in the appropriate projective space.'

 degenerate primes

  * only over ZZ or QQ

 is_symmetric_oribt

  * fix 'ps`'

 lambda minus

  * change '-' to 'minus'

 lambda plus

  * change '+' to 'plus'

 nth_iterate_phi

  * write out 'phi'
  * quotes for `psi' is fine, but you should be consistent throughout the

 documentation. This is thefirst place you've done that.

 nth_iterate_phi

  * write out 'psi'

 orbit_phi

  * Function is defined in [!CaSi]

 phi

  * output: a point on self

 psi

  * output: a point on self

 sigmaX

  * !``self!`` - you have single quotes
  * change 'while we have two points in the fiber' to 'while we can split
 the fiber into pairs of points'

  * output: a point on self

 sigmaY

  * !``self!`` - you have single quotes
  * change 'while we have two points in the fiber' to 'while we can split
 the fiber into pairs of points'

  * output: a point on self

 you are inconsistent with the hyphenation of bilinear and biquadratic. I
 think it

 should not be hyphenated.

 ----
 For functionality

 fiber:

  * add a component = 0 example
  * shouldn't the last 3 cases have an else for component == 1?

 PP.<x0,x1,x2,y0,y1,y2> = !ProductProjectiveSpaces([2,2],GF(7))
 L = x0*y0 + x1*y1 - 1*x2*y2
 Q=(2*x0!^2 + x2*x0 + (2*x1!^2 + x2!^2))*y0!^2 + ((x0!^2 + x1*x0 +(x1!^2 +
 2*x2*x1 + x2!^2))*y1 + (2*x1!^2 + x2*x1 + x2!^2)*y2)*y0 + ((2*x0!^2+ (x1 +
 2*x2)*x0 + (2*x1!^2 + x2*x1))*y1!^2 + ((2*x1 + 2*x2)*x0 + (x1!^2 +x2*x1 +
 2*x2!^2))*y2*y1 + (2*x0!^2 + x1*x0 + (2*x1!^2 + x2!^2))*y2!^2)
 W = WehlerK3Surface([L,Q])
 W.fiber([4,0,1],0)

 Should have 2 points...

 ----
 PP.<x0,x1,x2,y0,y1,y2> = !ProductProjectiveSpaces([2,2],GF(7))
 L = x0*y0 + x1*y1 - 1*x2*y2
 Q = (2*y0!^2 + y2*y0 + (2*y1!^2 + y2!^2))*x0!^2 + ((y0!^2 + y1*y0 +(y1!^2
 + 2*y2*y1 + y2!^2))*x1 + (2*y1!^2 + y2*y1 + y2!^2)*x2)*x0 + ((2*y0!^2+ (y1
 + 2*y2)*y0 + (2*y1!^2 + y2*y1))*x1!^2 + ((2*y1 + 2*y2)*y0 + (y1!^2 +y2*y1
 + 2*y2!^2))*x2*x1 + (2*y0!^2 + y1*y0 + (2*y1!^2 + y2!^2))*x2!^2)
 W = WehlerK3Surface([L,Q])
 W.fiber([1,0,0],1)

 This is returning a point over base field with a entry in a quadratic
 extension. That is 2 issues.

 ----
 nth_iterates

  * Unless I'm missing something, the negative seems not to be working

 R.<x0,x1,x2,y0,y1,y2>=!PolynomialRing(QQ,6)
 L = (-y0 - y1)*x0 + (-y0*x1 - y2*x2)
 Q = (-y2*y0 - y1!^2)*x0!^2 + ((-y0!^2 - y2*y0 + (-y2*y1 - y2!^2))*x1 +
 (-y0!^2 - y2*y1)*x2)*x0 + ((-y0!^2 - y2*y0 - y2!^2)*x1!^2 + (-y2*y0 -
 y1!^2)*x2*x1 + (-y0!^2 + (-y1 - y2)*y0)*x2!^2)
 X = WehlerK3Surface([L,Q])
 P = X([1,0,-1,1,-1,0])
 X.nth_iterate_phi(P,1)==X.nth_iterate_psi(P,-1)

--
Ticket URL: <http://trac.sagemath.org/ticket/17282#comment:20>
Sage <http://www.sagemath.org>
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