Groups > comp.soft-sys.math.mathematica > #3193

Re: Why doesn't TrueQ return True here?

From	Bob Hanlon <hanlonr@cox.net>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Re: Why doesn't TrueQ return True here?
Date	2011-06-20 12:05 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<itnd1n$7h2$1@smc.vnet.net> (permalink)

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??$Assumptions

$Assumptions is the default setting for the Assumptions option used in such functions as Simplify, Refine and Integrate. =C2 >>

$Assumptions=True


TrueQ is not one of the functions that makes use of $Assumptions.

$Assumptions = t2 > t1;

Simplify[(t2 - t1) > 0]

True

TrueQ[Simplify[(t2 - t1) > 0]]

True


Bob Hanlon

---- Jacare Omoplata <walkeystalkey@gmail.com> wrote:

=============
Here's the output.
-------------------------------------------------------
In[29]:= Element[{t1, t2}, Reals]

Out[29]= (t1 | t2) \[Element] Reals

In[30]:= $Assumptions = t2 > t1

Out[30]= t2 > t1

In[31]:= TrueQ[(t2 - t1) > 0]

Out[31]= False
------------------------------------------------------

I would expect TrueQ to return True, not False. Why does it return False?

And how can I test whether t2-t1 is positive?

Thanks.

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Re: Why doesn't TrueQ return True here? Bob Hanlon <hanlonr@cox.net> - 2011-06-20 12:05 +0000
  Re: Why doesn't TrueQ return True here? Jacare Omoplata <walkeystalkey@gmail.com> - 2011-06-20 23:37 +0000
    Re: Why doesn't TrueQ return True here? Jacare Omoplata <walkeystalkey@gmail.com> - 2011-06-21 09:52 +0000

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