Hi.

There is no unique faithful linear representation for a arbitrary finite group in general. (For arbitrary groups there is in general not a single faithful linear representation) I guess the only canonical choice is the regular representation, i.e. the group of permutation matrices that corresponds to the permutation action of G on itself via left-translation (or right-translation if you choose to act from the right). Therefore your way should be the easiest one to implement. Caveat: In general this procedure does not give you a faithful representation of smallest possible degree, i.e. it might be possible to find a "better" embedding in the sense that the matrices have smaller dimension. I don't think that there is some good way to do that besides the brute-force-way: Look through all characters of the group and check which are faithful. Then find a representation for this character (which is itself a nontrivial problem).

Johannes Hahn.

Am 21.11.2011 14:36, schrieb Robert Heffernan:
Hi,

Given a group G in GAP (eg. a group from the Small Groups library) is
there an easy way to get the group as a subgroup of a linear group?

I guess I could run IsomorphismPermGroup(G) and then get permutation
matrices for the generators.  Is there a better way to do it than
this?  A browse through the documentation didn't turn up anything
obvious.

Thank you,
Bob Heffernan

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