63.53 QuotientGraph

QuotientGraph( gamma, R )

Let S be the smallest gamma.group-invariant equivalence relation on the vertices of gamma, such that S contains the relation R (which should be a list of ordered pairs (length 2 lists) of vertices of gamma). Then this function returns a graph isomorphic to the quotient delta of the graph gamma, defined as follows. The vertices of delta are the equivalence classes of S, and [X,Y] is an edge of delta if and only if [x,y] is an edge of gamma for some x in X, y in Y.

    gap> gamma := JohnsonGraph(4,2);;
    gap> QuotientGraph( gamma, [[1,6]] );
    rec(
      isGraph := true,
      order := 3,
      group := Group( (1,2), (1,3), (2,3) ),
      schreierVector := [ -1, 1, 2 ],
      adjacencies := [ [ 2, 3 ] ],
      representatives := [ 1 ],
      isSimple := true,
      names := [ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 1, 3 ], [ 2, 4 ] ],
          [ [ 1, 4 ], [ 2, 3 ] ] ] ) 

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