Metamath Proof Explorer


Theorem revwlk

Description: The reverse of a walk is a walk. (Contributed by BTernaryTau, 30-Nov-2023)

Ref Expression
Assertion revwlk ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( reverse ‘ 𝐹 ) ( Walks ‘ 𝐺 ) ( reverse ‘ 𝑃 ) )

Proof

Step Hyp Ref Expression
1 eqid ( iEdg ‘ 𝐺 ) = ( iEdg ‘ 𝐺 )
2 1 wlkf ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝐹 ∈ Word dom ( iEdg ‘ 𝐺 ) )
3 revcl ( 𝐹 ∈ Word dom ( iEdg ‘ 𝐺 ) → ( reverse ‘ 𝐹 ) ∈ Word dom ( iEdg ‘ 𝐺 ) )
4 2 3 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( reverse ‘ 𝐹 ) ∈ Word dom ( iEdg ‘ 𝐺 ) )
5 eqid ( Vtx ‘ 𝐺 ) = ( Vtx ‘ 𝐺 )
6 5 wlkpwrd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑃 ∈ Word ( Vtx ‘ 𝐺 ) )
7 revcl ( 𝑃 ∈ Word ( Vtx ‘ 𝐺 ) → ( reverse ‘ 𝑃 ) ∈ Word ( Vtx ‘ 𝐺 ) )
8 wrdf ( ( reverse ‘ 𝑃 ) ∈ Word ( Vtx ‘ 𝐺 ) → ( reverse ‘ 𝑃 ) : ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝑃 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) )
9 6 7 8 3syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( reverse ‘ 𝑃 ) : ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝑃 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) )
10 revlen ( 𝐹 ∈ Word dom ( iEdg ‘ 𝐺 ) → ( ♯ ‘ ( reverse ‘ 𝐹 ) ) = ( ♯ ‘ 𝐹 ) )
11 2 10 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ ( reverse ‘ 𝐹 ) ) = ( ♯ ‘ 𝐹 ) )
12 11 oveq2d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ... ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) = ( 0 ... ( ♯ ‘ 𝐹 ) ) )
13 wlklenvp1 ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ 𝑃 ) = ( ( ♯ ‘ 𝐹 ) + 1 ) )
14 13 oveq2d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ..^ ( ♯ ‘ 𝑃 ) ) = ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
15 revlen ( 𝑃 ∈ Word ( Vtx ‘ 𝐺 ) → ( ♯ ‘ ( reverse ‘ 𝑃 ) ) = ( ♯ ‘ 𝑃 ) )
16 6 15 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ ( reverse ‘ 𝑃 ) ) = ( ♯ ‘ 𝑃 ) )
17 16 oveq2d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝑃 ) ) ) = ( 0 ..^ ( ♯ ‘ 𝑃 ) ) )
18 wlkcl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ 𝐹 ) ∈ ℕ0 )
19 18 nn0zd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ 𝐹 ) ∈ ℤ )
20 fzval3 ( ( ♯ ‘ 𝐹 ) ∈ ℤ → ( 0 ... ( ♯ ‘ 𝐹 ) ) = ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
21 19 20 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ... ( ♯ ‘ 𝐹 ) ) = ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
22 14 17 21 3eqtr4rd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ... ( ♯ ‘ 𝐹 ) ) = ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝑃 ) ) ) )
23 12 22 eqtrd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ... ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) = ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝑃 ) ) ) )
24 23 feq2d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( reverse ‘ 𝑃 ) : ( 0 ... ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) ↔ ( reverse ‘ 𝑃 ) : ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝑃 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) ) )
25 9 24 mpbird ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( reverse ‘ 𝑃 ) : ( 0 ... ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) )
26 11 oveq2d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) = ( 0 ..^ ( ♯ ‘ 𝐹 ) ) )
27 26 eleq2d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 𝑘 ∈ ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ↔ 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) )
28 27 biimpa ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ) → 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) )
29 revfv ( ( 𝐹 ∈ Word dom ( iEdg ‘ 𝐺 ) ∧ 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) = ( 𝐹 ‘ ( ( ( ♯ ‘ 𝐹 ) − 1 ) − 𝑘 ) ) )
30 2 29 sylan ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) = ( 𝐹 ‘ ( ( ( ♯ ‘ 𝐹 ) − 1 ) − 𝑘 ) ) )
31 wlklenvm1 ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ 𝐹 ) = ( ( ♯ ‘ 𝑃 ) − 1 ) )
32 31 oveq1d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( ♯ ‘ 𝐹 ) − 1 ) = ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) )
33 lencl ( 𝑃 ∈ Word ( Vtx ‘ 𝐺 ) → ( ♯ ‘ 𝑃 ) ∈ ℕ0 )
34 33 nn0cnd ( 𝑃 ∈ Word ( Vtx ‘ 𝐺 ) → ( ♯ ‘ 𝑃 ) ∈ ℂ )
35 sub1m1 ( ( ♯ ‘ 𝑃 ) ∈ ℂ → ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) = ( ( ♯ ‘ 𝑃 ) − 2 ) )
36 6 34 35 3syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) = ( ( ♯ ‘ 𝑃 ) − 2 ) )
37 32 36 eqtrd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( ♯ ‘ 𝐹 ) − 1 ) = ( ( ♯ ‘ 𝑃 ) − 2 ) )
38 37 fvoveq1d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 𝐹 ‘ ( ( ( ♯ ‘ 𝐹 ) − 1 ) − 𝑘 ) ) = ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) )
39 38 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 𝐹 ‘ ( ( ( ♯ ‘ 𝐹 ) − 1 ) − 𝑘 ) ) = ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) )
40 30 39 eqtrd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) = ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) )
41 40 fveq2d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) )
42 41 adantr ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) )
43 fzonn0p1p1 ( 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) → ( 𝑘 + 1 ) ∈ ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
44 43 adantl ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 𝑘 + 1 ) ∈ ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
45 14 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 0 ..^ ( ♯ ‘ 𝑃 ) ) = ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
46 44 45 eleqtrrd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 𝑘 + 1 ) ∈ ( 0 ..^ ( ♯ ‘ 𝑃 ) ) )
47 revfv ( ( 𝑃 ∈ Word ( Vtx ‘ 𝐺 ) ∧ ( 𝑘 + 1 ) ∈ ( 0 ..^ ( ♯ ‘ 𝑃 ) ) ) → ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) = ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 𝑘 + 1 ) ) ) )
48 6 46 47 syl2an2r ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) = ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 𝑘 + 1 ) ) ) )
49 elfzoelz ( 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) → 𝑘 ∈ ℤ )
50 49 zcnd ( 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) → 𝑘 ∈ ℂ )
51 50 adantl ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → 𝑘 ∈ ℂ )
52 1cnd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → 1 ∈ ℂ )
53 51 52 addcomd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 𝑘 + 1 ) = ( 1 + 𝑘 ) )
54 53 oveq2d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 𝑘 + 1 ) ) = ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 1 + 𝑘 ) ) )
55 6 34 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ 𝑃 ) ∈ ℂ )
56 55 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ♯ ‘ 𝑃 ) ∈ ℂ )
57 56 52 subcld ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ♯ ‘ 𝑃 ) − 1 ) ∈ ℂ )
58 57 52 51 subsub4d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) = ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 1 + 𝑘 ) ) )
59 36 oveq1d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) = ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) )
60 59 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) = ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) )
61 54 58 60 3eqtr2d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 𝑘 + 1 ) ) = ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) )
62 61 fveq2d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 1 ) − ( 𝑘 + 1 ) ) ) = ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) )
63 48 62 eqtrd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) = ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) )
64 63 sneqd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } )
65 64 adantr ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } )
66 sneq ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) → { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } = { ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } )
67 66 adantl ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } = { ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } )
68 eqcom ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ↔ ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) = ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) )
69 fzossfzop1 ( ( ♯ ‘ 𝐹 ) ∈ ℕ0 → ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ⊆ ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
70 18 69 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ⊆ ( 0 ..^ ( ( ♯ ‘ 𝐹 ) + 1 ) ) )
71 70 14 sseqtrrd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ⊆ ( 0 ..^ ( ♯ ‘ 𝑃 ) ) )
72 71 sselda ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝑃 ) ) )
73 revfv ( ( 𝑃 ∈ Word ( Vtx ‘ 𝐺 ) ∧ 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝑃 ) ) ) → ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) ) )
74 6 72 73 syl2an2r ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) ) )
75 57 51 52 sub32d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) − 1 ) = ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) )
76 75 oveq1d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) − 1 ) + 1 ) = ( ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) + 1 ) )
77 57 51 subcld ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) ∈ ℂ )
78 77 52 npcand ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) − 1 ) + 1 ) = ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) )
79 59 oveq1d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) + 1 ) = ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) )
80 79 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 1 ) − 𝑘 ) + 1 ) = ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) )
81 76 78 80 3eqtr3d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) = ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) )
82 81 fveq2d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 1 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) )
83 74 82 eqtrd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) )
84 63 83 eqeq12d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) = ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) ↔ ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) ) )
85 68 84 syl5bb ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ↔ ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) ) )
86 wkslem1 ( 𝑥 = ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) → ( if- ( ( 𝑃𝑥 ) = ( 𝑃 ‘ ( 𝑥 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) = { ( 𝑃𝑥 ) } , { ( 𝑃𝑥 ) , ( 𝑃 ‘ ( 𝑥 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) ) ↔ if- ( ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } , { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) ) )
87 5 1 wlkprop ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 𝐹 ∈ Word dom ( iEdg ‘ 𝐺 ) ∧ 𝑃 : ( 0 ... ( ♯ ‘ 𝐹 ) ) ⟶ ( Vtx ‘ 𝐺 ) ∧ ∀ 𝑥 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) if- ( ( 𝑃𝑥 ) = ( 𝑃 ‘ ( 𝑥 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) = { ( 𝑃𝑥 ) } , { ( 𝑃𝑥 ) , ( 𝑃 ‘ ( 𝑥 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) ) ) )
88 87 simp3d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ∀ 𝑥 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) if- ( ( 𝑃𝑥 ) = ( 𝑃 ‘ ( 𝑥 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) = { ( 𝑃𝑥 ) } , { ( 𝑃𝑥 ) , ( 𝑃 ‘ ( 𝑥 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) ) )
89 88 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ∀ 𝑥 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) if- ( ( 𝑃𝑥 ) = ( 𝑃 ‘ ( 𝑥 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) = { ( 𝑃𝑥 ) } , { ( 𝑃𝑥 ) , ( 𝑃 ‘ ( 𝑥 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹𝑥 ) ) ) )
90 18 nn0cnd ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ♯ ‘ 𝐹 ) ∈ ℂ )
91 90 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ♯ ‘ 𝐹 ) ∈ ℂ )
92 91 51 52 sub32d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝐹 ) − 𝑘 ) − 1 ) = ( ( ( ♯ ‘ 𝐹 ) − 1 ) − 𝑘 ) )
93 37 adantr ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ♯ ‘ 𝐹 ) − 1 ) = ( ( ♯ ‘ 𝑃 ) − 2 ) )
94 93 oveq1d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝐹 ) − 1 ) − 𝑘 ) = ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) )
95 92 94 eqtrd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝐹 ) − 𝑘 ) − 1 ) = ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) )
96 ubmelm1fzo ( 𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) → ( ( ( ♯ ‘ 𝐹 ) − 𝑘 ) − 1 ) ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) )
97 96 adantl ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝐹 ) − 𝑘 ) − 1 ) ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) )
98 95 97 eqeltrrd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) )
99 86 89 98 rspcdva ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → if- ( ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } , { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) )
100 dfifp2 ( if- ( ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } , { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) ↔ ( ( ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } ) ∧ ( ¬ ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) → { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) ) )
101 99 100 sylib ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } ) ∧ ( ¬ ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) → { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) ) )
102 101 simpld ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } ) )
103 85 102 sylbid ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } ) )
104 103 imp ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) } )
105 65 67 104 3eqtr4rd ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } )
106 42 105 eqtrd ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } )
107 85 notbid ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ¬ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ↔ ¬ ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) ) )
108 101 simprd ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ¬ ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) = ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) → { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) )
109 107 108 sylbid ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → ( ¬ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) → { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) ) )
110 109 imp ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ¬ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) )
111 prcom { ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) }
112 63 83 preq12d ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } )
113 111 112 eqtr3id ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } )
114 113 adantr ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ¬ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } = { ( 𝑃 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) , ( 𝑃 ‘ ( ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) + 1 ) ) } )
115 41 adantr ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ¬ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = ( ( iEdg ‘ 𝐺 ) ‘ ( 𝐹 ‘ ( ( ( ♯ ‘ 𝑃 ) − 2 ) − 𝑘 ) ) ) )
116 110 114 115 3sstr4d ( ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) ∧ ¬ ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) ) → { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) )
117 106 116 ifpimpda ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ 𝐹 ) ) ) → if- ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } , { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) ) )
118 28 117 syldan ( ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝑘 ∈ ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ) → if- ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } , { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) ) )
119 118 ralrimiva ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ∀ 𝑘 ∈ ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) if- ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } , { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) ) )
120 wlkv ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( 𝐺 ∈ V ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V ) )
121 120 simp1d ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃𝐺 ∈ V )
122 5 1 iswlkg ( 𝐺 ∈ V → ( ( reverse ‘ 𝐹 ) ( Walks ‘ 𝐺 ) ( reverse ‘ 𝑃 ) ↔ ( ( reverse ‘ 𝐹 ) ∈ Word dom ( iEdg ‘ 𝐺 ) ∧ ( reverse ‘ 𝑃 ) : ( 0 ... ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) ∧ ∀ 𝑘 ∈ ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) if- ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } , { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) ) ) ) )
123 121 122 syl ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( ( reverse ‘ 𝐹 ) ( Walks ‘ 𝐺 ) ( reverse ‘ 𝑃 ) ↔ ( ( reverse ‘ 𝐹 ) ∈ Word dom ( iEdg ‘ 𝐺 ) ∧ ( reverse ‘ 𝑃 ) : ( 0 ... ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) ⟶ ( Vtx ‘ 𝐺 ) ∧ ∀ 𝑘 ∈ ( 0 ..^ ( ♯ ‘ ( reverse ‘ 𝐹 ) ) ) if- ( ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) = ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) , ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) = { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) } , { ( ( reverse ‘ 𝑃 ) ‘ 𝑘 ) , ( ( reverse ‘ 𝑃 ) ‘ ( 𝑘 + 1 ) ) } ⊆ ( ( iEdg ‘ 𝐺 ) ‘ ( ( reverse ‘ 𝐹 ) ‘ 𝑘 ) ) ) ) ) )
124 4 25 119 123 mpbir3and ( 𝐹 ( Walks ‘ 𝐺 ) 𝑃 → ( reverse ‘ 𝐹 ) ( Walks ‘ 𝐺 ) ( reverse ‘ 𝑃 ) )