#19040: rewrite Expression.__nonzero__()
-------------------------+-------------------------------------------------
Reporter: rws | Owner:
Type: | Status: new
enhancement | Milestone: sage-6.9
Priority: major | Resolution:
Component: | Merged in:
symbolics | Reviewers:
Keywords: | Work issues:
Authors: Ralf | Commit:
Stephan | 5f4ffc0b8929f971c649339ce451189ce6d8698d
Report Upstream: N/A | Stopgaps:
Branch: |
u/rws/19040-1 |
Dependencies: |
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Comment (by vdelecroix):
A small remark: From the documentation of the method `holds`
{{{
If Sage knows exactly that the relation is
undecidable it will throw an ``AttributeError``.
}}}
For '''one''' relation there '''always''' is an algorithm which is either
`return True` or `return False`. What is not possible is to design an
algorithm whose input is an equation and answers the validity of the
input. Your sentence makes no sense. A right formulation would be
{{{
If Sage does not know if the equation is valid it will
throw a ``NotImplementedError``. Note that the validity
of equations is an undecidable problem. Hence there will
always be instances for which such error is raised.
}}}
(`AttributeError` makes no sense here).
--
Ticket URL: <http://trac.sagemath.org/ticket/19040#comment:24>
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