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Groups > comp.soft-sys.math.mathematica > #3571

Re: Unwanted Recursion

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On 2011-07-07 13:48:07 +0200, DrMajorBob said:

> ClearAll@p
> SetAttributes[p, {Flat, OneIdentity}]
> p[a_] := a
> p[a]
> 
> a
> 
> Bobby
> 
> On Wed, 06 Jul 2011 04:39:33 -0500, Casorati <casorati@f-m.fm> wrote:
> 
>> I'm trying to define an anti-commutative algebra in Mathematica.
>> Here I will show only a minimal example to demonstrate my point.
>> The product of two elements a^b should be give by p[a,b] so I
>> make p flat:
>> 
>> SetAttributes[p, {Flat}]
>> 
>> But now I want p[a] to reduce to a.
>> Such a  rule would make other rules much simpler but when I define
>> 
>> p[a_] := a
>> 
>> the expression p[a] causes an infinite recursion. I get the message
>> 
>> $IterationLimit::itlim: Iteration limit of 4096 exceeded.
>> 
>> I have similar problems with p[]:=1 which makes mathematica puts
>> ones into the p : p[a]=p[a,a]=p[1,1,...,a] .
>> 
>> How can I solve this problem?

SetAttributes[p, {Flat, OneIdentity}]
p[a_] := a
p[] := 1
p[a]
$IterationLimit::itlim :  "Iteration limit of 4096 exceeded. \

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Re: Unwanted Recursion DrMajorBob <btreat1@austin.rr.com> - 2011-07-07 11:48 +0000
  Re: Unwanted Recursion Kambis Veschgini <k.veschgini@thphys.uni-heidelberg.de> - 2011-07-08 08:58 +0000

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