1 | 7. L: Vertices(the_graph) List 8. no_repeats(Vertices(the_graph);L) 9. y:Vertices(the_graph). (y L) no_repeats(Vertices(the_graph);list_accum(s',x'.( l,x. if P(x) [x / l] else l fi)(s',x');nil;L)) & ( x:Vertices(the_graph). (x list_accum(s',x'.( l,x. if P(x) [x / l] else l fi)(s',x');nil;L))  P(x)) | 2 steps |