Status: Valid
Owner: ----
Labels: Type-Defect Priority-Medium Assumptions
New issue 3496 by [email protected]: Assumptions known_facts only apply to
atomic expressions
http://code.google.com/p/sympy/issues/detail?id=3496
Assumptions has a mechanism to allow some predicates to imply others.
known_facts = { ...
Implies(Q.lower_triangular, Q.triangular),
Implies(Q.upper_triangular, Q.triangular),
...}
Which enables successful queries as follows
In [4]: ask(Q.triangular(X), Q.lower_triangular(X))
Out[4]: True
Unfortunately this implication does not propagate to larger queries like
the following
In [5]: ask(Q.triangular(X+Y), Q.lower_triangular(X) &
Q.lower_triangular(Y))
<returns None>
Despite the fact that the X+Y bit is handled in a handler
In [3]: ask(Q.lower_triangular(X+Y), Q.lower_triangular(X) &
Q.lower_triangular(Y))
Out[3]: True
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