let G1 be _Graph; for G2 being Subgraph of G1
for x, y, e being set st e Joins x,y,G2 holds
G1 .walkOf (x,e,y) = G2 .walkOf (x,e,y)
let G2 be Subgraph of G1; for x, y, e being set st e Joins x,y,G2 holds
G1 .walkOf (x,e,y) = G2 .walkOf (x,e,y)
let x, y, e be set ; ( e Joins x,y,G2 implies G1 .walkOf (x,e,y) = G2 .walkOf (x,e,y) )
assume A1:
e Joins x,y,G2
; G1 .walkOf (x,e,y) = G2 .walkOf (x,e,y)
then A2:
e Joins x,y,G1
by GLIB_000:72;
G2 .walkOf (x,e,y) = <*x,e,y*>
by A1, Def5;
hence
G1 .walkOf (x,e,y) = G2 .walkOf (x,e,y)
by A2, Def5; verum