Re: Simplifying algebraic expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg66881] Re: [mg66839] Simplifying algebraic expressions*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Fri, 2 Jun 2006 04:09:19 -0400 (EDT)*References*: <200606011054.GAA20566@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 1 Jun 2006, at 19:54, 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 > Note that you are using {} instead of (). Different kind of brackets have completely different meaning in Mathematica. I have found it amazingly hard to force Mathematica to perform this simplification. The best I could do is this. We need two rules. rule1 will replace 2x by u and 3y by v. rule 2 does the opposite: it replaces u by 2x and v by 2y. rule1 = {2x -> u, 3y -> v};rule2 = Map[Reverse, rule1]; Now: Simplify[TrigFactor[ FullSimplify[ExpToTrig[ FullSimplify[ ComplexExpand[ (-1)^(2*x + 3*y) /. rule1], Mod[u, 2] == 0] /. rule2], y â?? Integers]], y â?? Integers] (-1)^y Uff... Surely, this ought to be easier... Andrzej Kozlowski Tokyo, Japan

**Follow-Ups**:**Re: Re: Simplifying algebraic expressions***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>

**References**:**Simplifying algebraic expressions***From:*Amitabha Roy <aroy@cs.bc.edu>