let G1, G2 be _Graph; for x being set st G1 == G2 & x is Walk of G1 holds
x is Walk of G2
let x be set ; ( G1 == G2 & x is Walk of G1 implies x is Walk of G2 )
assume that
A1:
G1 == G2
and
A2:
x is Walk of G1
; x is Walk of G2
A3:
the_Vertices_of G1 = the_Vertices_of G2
by A1, GLIB_000:def 34;
then reconsider W = x as FinSequence of (the_Vertices_of G2) \/ (the_Edges_of G2) by A1, A2, GLIB_000:def 34;
A4:
now let n be
odd Element of
NAT ;
( n < len W implies W . (n + 1) Joins W . n,W . (n + 2),G2 )assume
n < len W
;
W . (n + 1) Joins W . n,W . (n + 2),G2then
W . (n + 1) Joins W . n,
W . (n + 2),
G1
by A2, Def3;
hence
W . (n + 1) Joins W . n,
W . (n + 2),
G2
by A1, GLIB_000:88;
verum end;
W . 1 in the_Vertices_of G2
by A2, A3, Def3;
hence
x is Walk of G2
by A2, A4, Def3; verum