Status: Accepted
Owner: ----
Labels: Type-Defect Priority-Medium WrongResult Assumptions
New issue 2877 by asmeu...@gmail.com: Contradictory facts about infinities
in the new assumptions
http://code.google.com/p/sympy/issues/detail?id=2877
We have
In [13]: ask(Q.real(oo))
Out[13]: False
In [14]: ask(Q.positive(oo))
Out[14]: True
In [15]: ask(Q.real(x), Q.positive(x))
Out[15]: True
which is of course a contradiction. The old assumptions give:
In [16]: oo.is_real
Out[16]: True
In [17]: oo.is_positive
Out[17]: True
In [18]: x = Symbol('x', positive=True)
In [19]: x.is_real
Out[19]: True
We need to decide exactly what sets real, positive, etc. define, and
document them (issue 2196). Personally, I think real, positive, etc.
should only define finite numbers, and we should have extended_real, etc.
to include infinities. But no matter what we do, it needs to be
consistant, and well documented.
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