set V = {1,2};
set E = {} ;
reconsider S = {} as Function of {},{1,2} by RELSET_1:12;
set G = createGraph ({1,2},{},S,S);
take
createGraph ({1,2},{},S,S)
; ( createGraph ({1,2},{},S,S) is _finite & not createGraph ({1,2},{},S,S) is _trivial & createGraph ({1,2},{},S,S) is simple )
thus
createGraph ({1,2},{},S,S) is _finite
; ( not createGraph ({1,2},{},S,S) is _trivial & createGraph ({1,2},{},S,S) is simple )
card (the_Vertices_of (createGraph ({1,2},{},S,S))) <> 1
by CARD_2:57;
hence
not createGraph ({1,2},{},S,S) is _trivial
; createGraph ({1,2},{},S,S) is simple
A4:
createGraph ({1,2},{},S,S) is loopless
;
for e1, e2, v1, v2 being object st e1 Joins v1,v2, createGraph ({1,2},{},S,S) & e2 Joins v1,v2, createGraph ({1,2},{},S,S) holds
e1 = e2
;
then
createGraph ({1,2},{},S,S) is non-multi
;
hence
createGraph ({1,2},{},S,S) is simple
by A4; verum