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Re: Simplifying algebraic expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66899] Re: [mg66839] Simplifying algebraic expressions
  • From: Amitabha Roy <aroy at cs.bc.edu>
  • Date: Sat, 3 Jun 2006 03:25:23 -0400 (EDT)
  • References: <200606011054.GAA20566@smc.vnet.net> <44803200.7000104@wolfram.com>
  • Sender: owner-wri-mathgroup at wolfram.com

In Mathematica 5.2,

this does not work

Simplify[ (-1)^(2 x  + 3 y), Element[{x, y}, Integers] ]
gives no simplication. Neither does Refine.

I forgot to mention that I am only interested in the situation when  
the variables take on integer values.






On Jun 2, 2006, at 8:41 AM, Carl K. Woll wrote:

> Amitabha Roy wrote:
>> Hello:
>> I would like Mathematica to be able to take an expression, say,
>> (-1)^{2 x  + 3 y} and be able to simplify to (-1)^y.
>> Is there a way one can do this ?
>> Thanks
>
> I presume you want this simplification to occur assuming x and y  
> are integers, as the simplification is not valid when either x or y  
> are not integers. For example, with x==0 and y==.1, we have (-1)^ 
> (3*.1) != (-1)^.1. Try:
>
> Simplify[ (-1)^(2 x  + 3 y), Element[{x,y},Integers] ]
>
>     y
> (-1)
>
> (you could also use Refine with the same syntax instead of Simplify)
>
> Carl Woll
> Wolfram Research


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