| Step | Hyp | Ref | Expression | 
						
							| 1 |  | isclwwlknon | ⊢ ( 𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ↔  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 ) ) | 
						
							| 2 |  | eqid | ⊢ ( Vtx ‘ 𝐺 )  =  ( Vtx ‘ 𝐺 ) | 
						
							| 3 | 2 | clwwlknbp | ⊢ ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 ) ) | 
						
							| 4 |  | simpll | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  𝑊  ∈  Word  ( Vtx ‘ 𝐺 ) ) | 
						
							| 5 |  | uzuzle23 | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  𝑁  ∈  ( ℤ≥ ‘ 2 ) ) | 
						
							| 6 |  | eluzfz2 | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 2 )  →  𝑁  ∈  ( 2 ... 𝑁 ) ) | 
						
							| 7 | 5 6 | syl | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  𝑁  ∈  ( 2 ... 𝑁 ) ) | 
						
							| 8 | 7 | adantl | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  𝑁  ∈  ( 2 ... 𝑁 ) ) | 
						
							| 9 |  | oveq2 | ⊢ ( ( ♯ ‘ 𝑊 )  =  𝑁  →  ( 2 ... ( ♯ ‘ 𝑊 ) )  =  ( 2 ... 𝑁 ) ) | 
						
							| 10 | 9 | eleq2d | ⊢ ( ( ♯ ‘ 𝑊 )  =  𝑁  →  ( 𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) )  ↔  𝑁  ∈  ( 2 ... 𝑁 ) ) ) | 
						
							| 11 | 10 | ad2antlr | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( 𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) )  ↔  𝑁  ∈  ( 2 ... 𝑁 ) ) ) | 
						
							| 12 | 8 11 | mpbird | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) | 
						
							| 13 | 4 12 | jca | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) ) | 
						
							| 14 | 13 | ex | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) ) ) | 
						
							| 15 | 3 14 | syl | ⊢ ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) ) ) | 
						
							| 16 | 15 | adantr | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) ) ) | 
						
							| 17 | 1 16 | sylbi | ⊢ ( 𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) ) ) | 
						
							| 18 | 17 | impcom | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 ) )  →  ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) ) ) | 
						
							| 19 |  | swrds2m | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  𝑁  ∈  ( 2 ... ( ♯ ‘ 𝑊 ) ) )  →  ( 𝑊  substr  〈 ( 𝑁  −  2 ) ,  𝑁 〉 )  =  〈“ ( 𝑊 ‘ ( 𝑁  −  2 ) ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 20 | 18 19 | syl | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 ) )  →  ( 𝑊  substr  〈 ( 𝑁  −  2 ) ,  𝑁 〉 )  =  〈“ ( 𝑊 ‘ ( 𝑁  −  2 ) ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 21 | 20 | 3adant3 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( 𝑊  substr  〈 ( 𝑁  −  2 ) ,  𝑁 〉 )  =  〈“ ( 𝑊 ‘ ( 𝑁  −  2 ) ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 22 |  | simp3 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) ) | 
						
							| 23 |  | eqidd | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  =  ( 𝑊 ‘ ( 𝑁  −  1 ) ) ) | 
						
							| 24 | 22 23 | s2eqd | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  〈“ ( 𝑊 ‘ ( 𝑁  −  2 ) ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉  =  〈“ ( 𝑊 ‘ 0 ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 25 |  | simpr | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  ( 𝑊 ‘ 0 )  =  𝑋 ) | 
						
							| 26 |  | eqidd | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  =  ( 𝑊 ‘ ( 𝑁  −  1 ) ) ) | 
						
							| 27 | 25 26 | s2eqd | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  〈“ ( 𝑊 ‘ 0 ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉  =  〈“ 𝑋 ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 28 | 1 27 | sylbi | ⊢ ( 𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  →  〈“ ( 𝑊 ‘ 0 ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉  =  〈“ 𝑋 ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 29 | 28 | 3ad2ant2 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  〈“ ( 𝑊 ‘ 0 ) ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉  =  〈“ 𝑋 ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 30 | 21 24 29 | 3eqtrd | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( 𝑊  substr  〈 ( 𝑁  −  2 ) ,  𝑁 〉 )  =  〈“ 𝑋 ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉 ) | 
						
							| 31 |  | clwwlknonmpo | ⊢ ( ClWWalksNOn ‘ 𝐺 )  =  ( 𝑣  ∈  ( Vtx ‘ 𝐺 ) ,  𝑛  ∈  ℕ0  ↦  { 𝑤  ∈  ( 𝑛  ClWWalksN  𝐺 )  ∣  ( 𝑤 ‘ 0 )  =  𝑣 } ) | 
						
							| 32 | 31 | elmpocl1 | ⊢ ( 𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  →  𝑋  ∈  ( Vtx ‘ 𝐺 ) ) | 
						
							| 33 | 32 | 3ad2ant2 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  𝑋  ∈  ( Vtx ‘ 𝐺 ) ) | 
						
							| 34 |  | eluzge3nn | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  𝑁  ∈  ℕ ) | 
						
							| 35 |  | fzo0end | ⊢ ( 𝑁  ∈  ℕ  →  ( 𝑁  −  1 )  ∈  ( 0 ..^ 𝑁 ) ) | 
						
							| 36 | 34 35 | syl | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑁  −  1 )  ∈  ( 0 ..^ 𝑁 ) ) | 
						
							| 37 | 36 | adantl | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( 𝑁  −  1 )  ∈  ( 0 ..^ 𝑁 ) ) | 
						
							| 38 |  | oveq2 | ⊢ ( ( ♯ ‘ 𝑊 )  =  𝑁  →  ( 0 ..^ ( ♯ ‘ 𝑊 ) )  =  ( 0 ..^ 𝑁 ) ) | 
						
							| 39 | 38 | ad2antlr | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( 0 ..^ ( ♯ ‘ 𝑊 ) )  =  ( 0 ..^ 𝑁 ) ) | 
						
							| 40 | 39 | eleq2d | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( ( 𝑁  −  1 )  ∈  ( 0 ..^ ( ♯ ‘ 𝑊 ) )  ↔  ( 𝑁  −  1 )  ∈  ( 0 ..^ 𝑁 ) ) ) | 
						
							| 41 | 37 40 | mpbird | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( 𝑁  −  1 )  ∈  ( 0 ..^ ( ♯ ‘ 𝑊 ) ) ) | 
						
							| 42 |  | wrdsymbcl | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( 𝑁  −  1 )  ∈  ( 0 ..^ ( ♯ ‘ 𝑊 ) ) )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) | 
						
							| 43 | 4 41 42 | syl2anc | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  𝑁  ∈  ( ℤ≥ ‘ 3 ) )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) | 
						
							| 44 | 43 | ex | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) ) | 
						
							| 45 | 3 44 | syl | ⊢ ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) ) | 
						
							| 46 | 45 | adantr | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) ) | 
						
							| 47 | 1 46 | sylbi | ⊢ ( 𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  →  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) ) | 
						
							| 48 | 47 | impcom | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 ) )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) | 
						
							| 49 | 48 | 3adant3 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 ) ) | 
						
							| 50 |  | preq1 | ⊢ ( ( 𝑊 ‘ 0 )  =  𝑋  →  { ( 𝑊 ‘ 0 ) ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  =  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) } ) | 
						
							| 51 | 50 | adantl | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  { ( 𝑊 ‘ 0 ) ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  =  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) } ) | 
						
							| 52 | 51 | eqcomd | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  =  { ( 𝑊 ‘ 0 ) ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) } ) | 
						
							| 53 | 52 | 3ad2ant2 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  =  { ( 𝑊 ‘ 0 ) ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) } ) | 
						
							| 54 |  | prcom | ⊢ { ( 𝑊 ‘ 0 ) ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  =  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) } | 
						
							| 55 | 53 54 | eqtrdi | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  =  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) } ) | 
						
							| 56 |  | eqid | ⊢ ( Edg ‘ 𝐺 )  =  ( Edg ‘ 𝐺 ) | 
						
							| 57 | 2 56 | clwwlknp | ⊢ ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  →  ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( 𝑁  −  1 ) ) { ( 𝑊 ‘ 𝑖 ) ,  ( 𝑊 ‘ ( 𝑖  +  1 ) ) }  ∈  ( Edg ‘ 𝐺 )  ∧  { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) | 
						
							| 58 | 57 | adantr | ⊢ ( ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  →  ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( 𝑁  −  1 ) ) { ( 𝑊 ‘ 𝑖 ) ,  ( 𝑊 ‘ ( 𝑖  +  1 ) ) }  ∈  ( Edg ‘ 𝐺 )  ∧  { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) | 
						
							| 59 | 58 | 3ad2ant2 | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( 𝑁  −  1 ) ) { ( 𝑊 ‘ 𝑖 ) ,  ( 𝑊 ‘ ( 𝑖  +  1 ) ) }  ∈  ( Edg ‘ 𝐺 )  ∧  { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) | 
						
							| 60 |  | lsw | ⊢ ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  →  ( lastS ‘ 𝑊 )  =  ( 𝑊 ‘ ( ( ♯ ‘ 𝑊 )  −  1 ) ) ) | 
						
							| 61 |  | fvoveq1 | ⊢ ( ( ♯ ‘ 𝑊 )  =  𝑁  →  ( 𝑊 ‘ ( ( ♯ ‘ 𝑊 )  −  1 ) )  =  ( 𝑊 ‘ ( 𝑁  −  1 ) ) ) | 
						
							| 62 | 60 61 | sylan9eq | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  →  ( lastS ‘ 𝑊 )  =  ( 𝑊 ‘ ( 𝑁  −  1 ) ) ) | 
						
							| 63 | 62 | adantr | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) ) )  →  ( lastS ‘ 𝑊 )  =  ( 𝑊 ‘ ( 𝑁  −  1 ) ) ) | 
						
							| 64 | 63 | preq1d | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) ) )  →  { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  =  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) } ) | 
						
							| 65 | 64 | eleq1d | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) ) )  →  ( { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 )  ↔  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) | 
						
							| 66 | 65 | biimpd | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) ) )  →  ( { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 )  →  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) | 
						
							| 67 | 66 | ex | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  →  ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 )  →  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) ) | 
						
							| 68 | 67 | com23 | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  →  ( { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 )  →  ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) ) | 
						
							| 69 | 68 | a1d | ⊢ ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  →  ( ∀ 𝑖  ∈  ( 0 ..^ ( 𝑁  −  1 ) ) { ( 𝑊 ‘ 𝑖 ) ,  ( 𝑊 ‘ ( 𝑖  +  1 ) ) }  ∈  ( Edg ‘ 𝐺 )  →  ( { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 )  →  ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) ) ) | 
						
							| 70 | 69 | 3imp | ⊢ ( ( ( 𝑊  ∈  Word  ( Vtx ‘ 𝐺 )  ∧  ( ♯ ‘ 𝑊 )  =  𝑁 )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( 𝑁  −  1 ) ) { ( 𝑊 ‘ 𝑖 ) ,  ( 𝑊 ‘ ( 𝑖  +  1 ) ) }  ∈  ( Edg ‘ 𝐺 )  ∧  { ( lastS ‘ 𝑊 ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) )  →  ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) ) | 
						
							| 71 | 59 70 | mpcom | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { ( 𝑊 ‘ ( 𝑁  −  1 ) ) ,  ( 𝑊 ‘ 0 ) }  ∈  ( Edg ‘ 𝐺 ) ) | 
						
							| 72 | 55 71 | eqeltrd | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  ( 𝑊  ∈  ( 𝑁  ClWWalksN  𝐺 )  ∧  ( 𝑊 ‘ 0 )  =  𝑋 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  ∈  ( Edg ‘ 𝐺 ) ) | 
						
							| 73 | 1 72 | syl3an2b | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  ∈  ( Edg ‘ 𝐺 ) ) | 
						
							| 74 |  | eqid | ⊢ ( ClWWalksNOn ‘ 𝐺 )  =  ( ClWWalksNOn ‘ 𝐺 ) | 
						
							| 75 | 74 2 56 | s2elclwwlknon2 | ⊢ ( ( 𝑋  ∈  ( Vtx ‘ 𝐺 )  ∧  ( 𝑊 ‘ ( 𝑁  −  1 ) )  ∈  ( Vtx ‘ 𝐺 )  ∧  { 𝑋 ,  ( 𝑊 ‘ ( 𝑁  −  1 ) ) }  ∈  ( Edg ‘ 𝐺 ) )  →  〈“ 𝑋 ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 2 ) ) | 
						
							| 76 | 33 49 73 75 | syl3anc | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  〈“ 𝑋 ( 𝑊 ‘ ( 𝑁  −  1 ) ) ”〉  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 2 ) ) | 
						
							| 77 | 30 76 | eqeltrd | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  ∧  𝑊  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 𝑁 )  ∧  ( 𝑊 ‘ ( 𝑁  −  2 ) )  =  ( 𝑊 ‘ 0 ) )  →  ( 𝑊  substr  〈 ( 𝑁  −  2 ) ,  𝑁 〉 )  ∈  ( 𝑋 ( ClWWalksNOn ‘ 𝐺 ) 2 ) ) |