let H be removeParallelEdges of G; not H is loopless
consider E being RepEdgeSelection of G such that
A1:
H is inducedSubgraph of G, the_Vertices_of G,E
by GLIB_009:def 7;
consider v being object such that
A2:
ex e being object st e Joins v,v,G
by GLIB_000:18;
consider e0 being object such that
A3:
e0 Joins v,v,G
by A2;
consider e being object such that
A4:
( e Joins v,v,G & e in E )
and
for e9 being object st e9 Joins v,v,G & e9 in E holds
e9 = e
by A3, GLIB_009:def 5;
A5:
the_Edges_of G = G .edgesBetween (the_Vertices_of G)
by GLIB_000:34;
the_Vertices_of G c= the_Vertices_of G
;
then A6:
e in the_Edges_of H
by A1, A4, A5, GLIB_000:def 37;
( v is set & e is set )
by TARSKI:1;
then
e Joins v,v,H
by A4, A6, GLIB_000:73;
hence
not H is loopless
by GLIB_000:18; verum