let G1 be _Graph; :: thesis: for G2 being Subgraph of G1
for W1 being Walk of G1
for W2 being Walk of G2 st W1 = W2 holds
( ( W1 is closed implies W2 is closed ) & ( W2 is closed implies W1 is closed ) & ( W1 is directed implies W2 is directed ) & ( W2 is directed implies W1 is directed ) & ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
let G2 be Subgraph of G1; :: thesis: for W1 being Walk of G1
for W2 being Walk of G2 st W1 = W2 holds
( ( W1 is closed implies W2 is closed ) & ( W2 is closed implies W1 is closed ) & ( W1 is directed implies W2 is directed ) & ( W2 is directed implies W1 is directed ) & ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
let W1 be Walk of G1; :: thesis: for W2 being Walk of G2 st W1 = W2 holds
( ( W1 is closed implies W2 is closed ) & ( W2 is closed implies W1 is closed ) & ( W1 is directed implies W2 is directed ) & ( W2 is directed implies W1 is directed ) & ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
let W2 be Walk of G2; :: thesis: ( W1 = W2 implies ( ( W1 is closed implies W2 is closed ) & ( W2 is closed implies W1 is closed ) & ( W1 is directed implies W2 is directed ) & ( W2 is directed implies W1 is directed ) & ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) ) )
assume A1: W1 = W2 ; :: thesis: ( ( W1 is closed implies W2 is closed ) & ( W2 is closed implies W1 is closed ) & ( W1 is directed implies W2 is directed ) & ( W2 is directed implies W1 is directed ) & ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
then A2: W1 .last() = W2 .last() ;
A3: ( W1 is closed iff W1 .first() = W1 .last() ) by Def24;
W1 .first() = W2 .first() by A1;
hence ( W1 is closed iff W2 is closed ) by A3, A2, Def24; :: thesis: ( ( W1 is directed implies W2 is directed ) & ( W2 is directed implies W1 is directed ) & ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )

now

hereby :: thesis: ( W2 is directed implies W1 is directed Walk of G1 )

assume A4: W1 is directed ; :: thesis: W2 is directed

now

let n be odd Element of NAT ; :: thesis: ( n < len W2 implies (the_Source_of G2) . (W2 . (n + 1)) = W2 . n )
A5: 1 <= n + 1 by NAT_1:12;
assume A6: n < len W2 ; :: thesis: (the_Source_of G2) . (W2 . (n + 1)) = W2 . n
then n + 1 <= len W2 by NAT_1:13;
then n + 1 in dom W2 by A5, FINSEQ_3:27;
then W2 . (n + 1) in the_Edges_of G2 by Th9;
then (the_Source_of G2) . (W2 . (n + 1)) = (the_Source_of G1) . (W2 . (n + 1)) by GLIB_000:def 34;
hence (the_Source_of G2) . (W2 . (n + 1)) = W2 . n by A1, A4, A6, Def25; :: thesis: verum

end;

hence W2 is directed by Def25; :: thesis: verum

end;

assume W2 is directed ; :: thesis: W1 is directed Walk of G1
hence W1 is directed Walk of G1 by A1, Th176; :: thesis: verum

end;

hence ( W1 is directed iff W2 is directed ) ; :: thesis: ( ( W1 is trivial implies W2 is trivial ) & ( W2 is trivial implies W1 is trivial ) & ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
( W1 is trivial iff len W2 = 1 ) by A1, Lm55;
hence ( W1 is trivial iff W2 is trivial ) by Lm55; :: thesis: ( ( W1 is Trail-like implies W2 is Trail-like ) & ( W2 is Trail-like implies W1 is Trail-like ) & ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
( W1 is Trail-like iff for m, n being even Element of NAT st 1 <= m & m < n & n <= len W2 holds
W2 . m <> W2 . n ) by A1, Lm57;
hence A7: ( W1 is Trail-like iff W2 is Trail-like ) by Lm57; :: thesis: ( ( W1 is Path-like implies W2 is Path-like ) & ( W2 is Path-like implies W1 is Path-like ) & ( W1 is vertex-distinct implies W2 is vertex-distinct ) & ( W2 is vertex-distinct implies W1 is vertex-distinct ) )
( W1 is Path-like iff ( W1 is Trail-like & ( for m, n being odd Element of NAT st m < n & n <= len W2 & W2 . m = W2 . n holds
( m = 1 & n = len W2 ) ) ) ) by A1, Def28;
hence ( W1 is Path-like iff W2 is Path-like ) by A7, Def28; :: thesis: ( W1 is vertex-distinct iff W2 is vertex-distinct )
( W1 is vertex-distinct iff for m, n being odd Element of NAT st m <= len W2 & n <= len W2 & W2 . m = W2 . n holds
m = n ) by A1, Def29;
hence ( W1 is vertex-distinct iff W2 is vertex-distinct ) by Def29; :: thesis: verum