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Strange result of a relational expression

asked 2012-02-20 20:43:00 -0600

seflyer gravatar image

updated 2012-02-21 04:52:38 -0600

DSM gravatar image

Tried the following in sage. The answer is False, which is apparently incorrect. Anyone ever encountered this before? Any idea on what happened here?


forget()
assume(x >= 0)
expr = sin(x) <= x
print(bool(expr))

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answered 2012-02-20 22:27:05 -0600

parzan gravatar image

See here: http://ask.sagemath.org/question/1144... and here: http://ask.sagemath.org/question/605/...

Quoting from DSM's answer:

"False" doesn't necessarily mean false, it might only mean "Sage couldn't figure out how to prove it was true.

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To elaborate, it is not possible to always prove something is false or true on a computer (at least not in the age of the universe...). Different programs might return different things in different logics, but Sage sticks with Python and returns only True or False to booleans.

kcrisman gravatar imagekcrisman ( 2012-02-21 02:12:10 -0600 )edit

I kind of get it, still I would say, whatever the evaluation algorithm is, a bug just showed itself and it might not be a good choice just treat it as something inevitable.

seflyer gravatar imageseflyer ( 2012-02-25 23:25:21 -0600 )edit

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Asked: 2012-02-20 20:43:00 -0600

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Last updated: Feb 21 '12