#11163: documentation of p-adic L-function  order_of_vanishing is very wrong
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   Reporter:  was            |       Owner:  was     
       Type:  defect         |      Status:  new     
   Priority:  minor          |   Milestone:  sage-4.7
  Component:  number theory  |    Keywords:          
     Author:                 |    Upstream:  N/A     
   Reviewer:                 |      Merged:          
Work_issues:                 |  
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 {{{
 To: Chris Wuthrich
 From: William Stein

 We have a function order_of_vanishing  on p-adic L-functions with
 docstring:

 -------------
 Definition:     L.order_of_vanishing(self)
 Source:
    def order_of_vanishing(self):
        r"""
        Return the order of vanishing of this `p`-adic L-series.

        The output of this function is provably correct, due to a
        theorem of Kato [Ka].  This function will terminate if and only if
        the Mazur-Tate-Teitelbaum analogue [MTT] of the BSD conjecture
 about
        the rank of the curve is true and the subgroup of elements of
        `p`-power order in the Tate-Shafarevich group of this curve is
        finite.  I.e. if this function terminates (with no errors!),
        then you may conclude that the `p`-adic BSD rank conjecture is
        true and that the `p`-part of Sha is finite.

 -------------

 The actual code doesn't call p-adic regulator anywhere.  However, in
 our paper we claim that not only does
 one have to verify that the order of vanishing of the analytic p-adic
 L-function equals the rank of the curve,
 but one also needs that the p-adic regulator is nonzero, in order to
 get the claimed conclusion that Sha is finite.
 That makes sense to me, since I don't think Schneider gets anywhere
 without knowing the height pairing
 is nondegenerate.

 So... is this a bug... I guess only in the documentation.  We could
 simply add to the documentation that if
 you call this function, get a number, and then *also* call
 padic_regulator and get a nonzero number, then
 you can conclude that Sha(p) is finite.

 William
 ----

 From: Chris Wuthrich
 To: William Stein

 I agree that the documentation is wrong. I would simply delete to
 mention Sha at all. This is probably better explained in p_primary
 bound. So a reference to this function could be included.

 Chris.
 }}}

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11163>
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