Aaron, what should be done in order to add new sat handlers?
I'm thinking where to start from? sympy/assumptions/sathandlers.py:
class IsEmptyOr1x1(UnevaluatedOnFree):
def apply(self):
return Equivalent(self.args[0], self.expr.shape == (0, 0) or
self.expr.shape == (1, 1))
for klass, fact in [
...
(MatrixExpr, IsEmptyOr1x1(Q.diagonal)),
(MatrixExpr, Implies(Q.diagonal, Q.symmetric)),
...
]
On Monday, December 12, 2016 at 4:04:57 PM UTC-8, Aaron Meurer wrote:
>
> This is a downside of the handlers system. The deductions aren't made
> based on facts that the handlers return. This is one of the main
> deficiencies that the satask/sathandlers system tries to fix. I don't
> know if there's an easy fix to make it work in the handlers system.
> You could also manually modify the SymmetricHandler class to check for
> diagonal (this is obviously annoying, because it blatantly duplicates
> the general fact in get_known_facts
>
> https://github.com/sympy/sympy/blob/5827cafb1e1840915b3e7c9f62cd0d58fff9fc48/sympy/assumptions/ask.py#L1517).
>
>
>
> The better way to fix it is to implement it in the sathandlers system.
> No matrix stuff is implemented there yet, so it may require some
> ground work.
>
> Aaron Meurer
>
> On Mon, Dec 12, 2016 at 6:57 PM, Andrey Torba <[email protected]
> <javascript:>> wrote:
> > Hi,
> >
> > I'm working on the pull request.
> >
> > A 1x1 matrix is always diagonal. Diagonal implies symmetric. I have
> fixed
> > AskDiagonalHandler such that this assertion pass:
> >
> > V1 = MatrixSymbol('V1', 2, 1)
> > V2 = MatrixSymbol('V2', 2, 1)
> > expr = V1.T*(V1 + V2)
> > assert ask(Q.diagonal(expr)) is True
> >
> > Now I assume that inference module will deduce that this expression is
> also
> > symmetric (since the expression is diagonal):
> >
> > assert ask(Q.symmetric(expr)) is True # it is None!
> >
> > It returns None. Is anything missing? Can you show an example where this
> > kind of inference works well?
> >
> > -Andrey
> >
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