[GAP Forum] GAP permutation question

[Dmitrii V Pasechnik (Asst Prof)]

Sorry, I thought that a permutation on the coordinates of the vectors
that makes L1=L2 equal as sets was sought. Otherwise it is indeed next
to trivial. 

Regards,
Dima
-----Original Message-----
From: forum-bounces at gap-system.org [mailto:forum-bounces at gap-system.org]
On Behalf Of Dima Pasechnik
Sent: Sunday, March 26, 2006 11:31 AM
To: David Joyner; GAP forum
Subject: Re: [GAP Forum] GAP permutation question

Dear all, dear David,

When L1, L2 are 0-1 matrices, one can use the package GRAPE to construct
(bipartite) graphs from them, and test them for isomorphism (such a
test, if successful, returns an isomorphism, too)

As GRAPE does not work with edge-coloured graphs, for more general
matrices this won't work, at least not out of the box.
One can think of constructing edge-coloured bipartite graphs, then their
vertex-coloured line graphs, and test the latter for the isomorphism.
(GRAPE can deal with vertex colourings).

One can probably use the general GAP backtracking on permutation groups,
but I doubt that this will be feasible for big matrices...

regards,
Dima



On 3/26/06 5:44 AM, "David Joyner" <wdjoyner at comcast.net> wrote:

> Hello all:
> 
> Let L1, L2 be lists of objects (lists of vectors or lists of strings).
> Is there a GAP function which returns a permutation which send L1 to 
> L2, if one exists, and "false" otherwise?
> 
> In case L1 = L2 = columns of a matrix M then the function could be 
> paired with the MatrixAutomorphism group of M to return an 
> "isomorphism" between two matrices.
> 
> - David Joyner
> 
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--
Dima Pasechnik
http://www.ntu.edu.sg/home/dima/



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