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< ^ Subject:

Dear GAP-Forum,

Pamb <pamb@mathematik.uni-wuerzburg.de> writes:

> Here is my question:

>

> I have a set S with 30 elements, together with a symmetric binary relation R, which

> holds between some of the elements of S. I would like to find out all the

> permutations of S which preserve the relation R, in the following precise sense

> f: S to S, f bijection satisfying "a R b if and only if f(a) R f(b)".

>

> Is there any program in GAP that would allow me to do that?

>

Yes, certainly. Namely, your question is just to find

the automorphism group of a graph

(with vertex set S and edge set {(a,b) in S x S | a R b})

The shared package GRAPE will do this for you in couple of commands.

HTH,

Dima

-- Dmitrii V. Pasechnik e-mail: d.pasechnik@its.tudelft.nl ISA, TWI/ITS office location: TU Delft HB 07.070 Postbus 5031 Mekelweg 4 2600 GA Delft 2628 CD Delft The Netherlands phone: +31-(0)15-2787260 fax: +31-(0)15-2786632 http://ssor.twi.tudelft.nl/~dima

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