let G be _Graph; for W being Walk of G st ( for n being odd Element of NAT st n <= len W holds
W .rfind n = n ) holds
W is Path-like
let W be Walk of G; ( ( for n being odd Element of NAT st n <= len W holds
W .rfind n = n ) implies W is Path-like )
assume A1:
for n being odd Element of NAT st n <= len W holds
W .rfind n = n
; W is Path-like
now for m, n being odd Element of NAT st m <= len W & n <= len W & W . m = W . n holds
m = nlet m,
n be
odd Element of
NAT ;
( m <= len W & n <= len W & W . m = W . n implies m = n )assume that A2:
m <= len W
and A3:
n <= len W
and A4:
W . m = W . n
;
m = n
W .rfind n = n
by A1, A3;
then A5:
m <= n
by A2, A3, A4, Def22;
W .rfind m = m
by A1, A2;
then
n <= m
by A2, A3, A4, Def22;
hence
m = n
by A5, XXREAL_0:1;
verum end;
hence
W is Path-like
by Lm66; verum