simple inequality check fails - why?

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L. C.
L. C. on 27 Jun 2012
Answered: timo on 2 Jan 2015
Hi,
I have the simple inequality check for testing purposes in MuPad:
assume(0<x<1)
assumeAlso(0<y<1)
assumeAlso(A>0)
is(1/(1-x) >=1/(1-x*y))
is(A/(1-x) >=A/(1-x*y))
The first check correctly evaluates to TRUE, but the second returns UNKNOWN, however it is obviously true. Am I doing something wrong, or I have reached the limitation of the tool?

Answers (3)

Tom
Tom on 27 Jun 2012
You have to split up the comparisons: e.g.:
x > 0 & x < 1
  1 Comment
L. C.
L. C. on 28 Jun 2012
Thanks. I tried and nothing has changed. Other ideas? I also tried to introduce an upper bound on A as well to avoid possible mess with infinity, but the result is just the same.

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Radu Trimbitas
Radu Trimbitas on 10 Sep 2014
Your code works works correctly in MATLAB 2014a.

timo
timo on 2 Jan 2015
For me evaluates to:
TRUE TRUE
in mupad for Symbolic Math Toolbox Version 6.1 (R2014b)

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