is mentioned by

Thm* For any graph the_obj:GraphObject(the_graph), L:V List. (i:V. (i L)) (non-trivial-loop-free(the_graph) topsortedl(the_graph;L;topsortl(the_obj;L))) & (i:V. (i topsortl(the_obj;L))) & no_repeats(V;topsortl(the_obj;L))	[topsortl-properties]
Thm* For any graph the_obj:GraphObject(the_graph). L:V List. (non-trivial-loop-free(the_graph) topsorted(the_graph;L)) & (i:V. (i L)) & no_repeats(V;L)	[topsort-exists]
Thm* For any graph the_obj:GraphObject(the_graph). (non-trivial-loop-free(the_graph) topsorted(the_graph;topsort(the_obj))) & (i:V. (i topsort(the_obj))) & no_repeats(V;topsort(the_obj))	[topsort-properties]

Try larger context: Graphs