63.64 AutGroupGraph

AutGroupGraph( gamma )
AutGroupGraph( gamma, colouring )

The first version of this function returns the automorphism group of the (directed) graph gamma, using nauty.

In the second version, colouring is a vertex-colouring of gamma, and the subgroup of Aut(<gamma>) preserving this colouring is returned. Here, a colouring should be given as a list of sets, forming a partion of the vertices. The set for the last colour may be omitted. Note that we do not require that adjacent vertices have different colours.

    gap> gamma := JohnsonGraph(4,2);;
    gap> Size(AutGroupGraph(gamma));
    48
    gap> Size(AutGroupGraph(gamma,[[1,6]]));
    16 

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