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Problem with Simplify and Assumptions

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  Problem with Simplify and Assumptions Cisco Lane <travlorf@yahoo.com> - 2011-05-25 09:57 +0000
    Re: Problem with Simplify and Assumptions ADL <alberto.dilullo@tiscali.it> - 2011-05-25 23:32 +0000

#2702 — Problem with Simplify and Assumptions

I am wondering how to get the last line to say "True"

In[1]:= $Assumptions = {m >= 1, s > 0}

Out[1]= {m >= 1, s > 0}

In[3]:= Simplify[(1 - 2*m)*s < 0]

Out[3]= True

In[4]:= Simplify[Exp[(1 - 2*m)*s] < 1]

Out[4]= E^s < E^(2 m s)

Thanks, 
Frank L.

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#2710

On 25 Mag, 11:57, Cisco Lane <travl...@yahoo.com> wrote:
> I am wondering how to get the last line to say "True"
>
> In[1]:= $Assumptions = {m >= 1, s > 0}
>
> Out[1]= {m >= 1, s > 0}
>
> In[3]:= Simplify[(1 - 2*m)*s < 0]
>
> Out[3]= True
>
> In[4]:= Simplify[Exp[(1 - 2*m)*s] < 1]
>
> Out[4]= E^s < E^(2 m s)
>
> Thanks,
> Frank L.

To look around Andrzej Kozlowski's suggestions, I observe that Reduce
seems to be insensitive to $Assumptions or Assuming, which is strange
(to me) and not mentioned in the help.

In any case,

In[]:= Reduce[m>=1 && s>0 && Exp[(1-2*m)*s]<1]
Out[]= m>=1 && s>0

which is a rather unusual way to express that the condition on Exp is
redundant (and thus disappeared).

In fact:

In[]:= Reduce[m >= 1 && s > 0 && Exp[(1 - 2*m)*s] >= 1]
Out[]= False

So, it seems to be easier to get a False than to get a True.

ADL

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