Re: Transformation rule problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg58085] Re: [mg58041] Transformation rule problem*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Fri, 17 Jun 2005 07:09:33 -0400 (EDT)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

expr=a^2 b^4+a^3 b+a^5+a^5 b; expr/.a^m_.*b^n_.:> (a^m*b^n*(d/a/b)^Min[m,n]) a^5 + d*a^4 + d*a^2 + b^2*d^2 Bob Hanlon > > From: Oliver Buerschaper <groo137vy at yahoo.co.uk> To: mathgroup at smc.vnet.net > Date: 2005/06/16 Thu AM 07:19:35 EDT > Subject: [mg58085] [mg58041] Transformation rule problem > > Hi there, > > I'm stuck with a problem concerning transformation rules and was > wondering whether somebody could give me a hint on this. I wouldn't > mind a complete solution either ;-) Here's the problem: > > In a sum like for example > > a^2 b^4 + a^3 b + a^5 + a^5 b > > I'd like to replace every instance of the product (a b) by a different > expression, let's call it d. Thus my result should look like > > d^2 b^2 + a^2 d + a^5 + a^4 d > > This replacement is required to work for arbitrary a and b (especially > when they're functions). I've already tried some simple transformation > rules but they couldn't do the job. > > Cheerio, > Oliver > >