Re: Problem with Simplify and Assumptions
- To: mathgroup at smc.vnet.net
- Subject: [mg119230] Re: Problem with Simplify and Assumptions
- From: ADL <alberto.dilullo at tiscali.it>
- Date: Wed, 25 May 2011 19:32:23 -0400 (EDT)
- References: <irijr5$qfu$1@smc.vnet.net>
On 25 Mag, 11:57, Cisco Lane <travl... at 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