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MathGroup Archive 1994

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Re: recognition puzzle

  • To: mathgroup at
  • Subject: [mg226] Re: [mg193] recognition puzzle
  • From: sfeir at
  • Date: Wed, 23 Nov 94 12:11:02 +0100

>Dear Mma puzzle fans:
>I have a list of several expressions; for example,
>{x^2  + 2 I x y - y^2 , 4 x^2  - 8 I x y - 4 y^2 }
>Mma has the list {x,y} of primitive variables.  I want it to recognize that
>these expressions are linear in only TWO cooked-up variables (namely,
>x^2-y^2 and x*y), and I want it to return the list {x^2-y^2,  x*y} to me.
>Is this an impossible  pattern recognition task?  Or is there a way to make
>Mma recognize the combination x^2-y^2 by its own "thought" processes?
>Regards-  Martin McClain, Chemistry, Wayne State, Deetroit

The package PatternRearrange in the Mathematica Journal 4.3 by Harris
addresses exactly this question. I beleive the package is also on

A.A. Sfeir                       e-mail:  sfeir at

Ecole des Mines                    Tel : (33) 83 58 40 15
Parc de Saurupt                          (33) 83 37 64 41
54042 Nancy Cedex   FRANCE          Fax: (33) 83 57 97 94

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