set IT = { W where W is Walk of G : verum } ;

A1: now

let x be set ; :: thesis: ( x in { W where W is Walk of G : verum } implies x in ((the_Vertices_of G) \/ (the_Edges_of G)) * )
assume x in { W where W is Walk of G : verum } ; :: thesis: x in ((the_Vertices_of G) \/ (the_Edges_of G)) *
then ex W being Walk of G st x = W ;
hence x in ((the_Vertices_of G) \/ (the_Edges_of G)) * by FINSEQ_1:def 11; :: thesis: verum

end;

G .walkOf (choose (the_Vertices_of G)) in { W where W is Walk of G : verum } ;
hence { W where W is Walk of G : verum } is non empty Subset of (((the_Vertices_of G) \/ (the_Edges_of G)) * ) by A1, TARSKI:def 3; :: thesis: verum