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Re: Simplifying multiple expressions

• To: mathgroup at smc.vnet.net
• Subject: [mg108959] Re: Simplifying multiple expressions
• From: telefunkenvf14 <rgorka at gmail.com>
• Date: Thu, 8 Apr 2010 08:02:06 -0400 (EDT)
• References: <hphbmd$li4$1@smc.vnet.net> <hphq6r$1ij$1@smc.vnet.net>

On Apr 7, 6:27 am, Simon <simonjty... at gmail.com> wrote:
> On Apr 7, 3:19 pm, Geico Caveman <spammers-go-h... at spam.invalid>
> wrote:
>
> > A question arising out of laziness.
>
> > I have about 20 expressions that I want to simplify using the same set
> > of assumptions. Is there an easy method for this ?
>
> Easiest way is if your objects _always_ satisfy some conditions is to
> set the global assumptions:
>
> $Assumptions = ...
>
> otherwise you could define your own assumptions that you pass to
> Simplify:
>
> myAssumptions = a>0 && b>1;
> Simplify[ a + b > 1, myAssumptions]

I like the global assumption route. If it matters, make sure you
evaluate $Assumptions=True after performing your intended tasks, to
reset.

Here's a question I've had for a while... Why does $Assumptions=True
make sense as the default setting? (I'm trying to understand this from
the Mathematica point of view---would have guessed $Assumptions=Null)

-RG