| Step | Hyp | Ref | Expression | 
						
							| 1 |  | clwlkwlk |  |-  ( c e. ( ClWalks ` G ) -> c e. ( Walks ` G ) ) | 
						
							| 2 |  | wlkcpr |  |-  ( c e. ( Walks ` G ) <-> ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) ) | 
						
							| 3 | 1 2 | sylib |  |-  ( c e. ( ClWalks ` G ) -> ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) ) | 
						
							| 4 |  | eqid |  |-  ( Vtx ` G ) = ( Vtx ` G ) | 
						
							| 5 | 4 | wlkpwrd |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 6 | 3 5 | syl |  |-  ( c e. ( ClWalks ` G ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 7 | 6 | 3ad2ant2 |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 8 |  | eluzge2nn0 |  |-  ( N e. ( ZZ>= ` 2 ) -> N e. NN0 ) | 
						
							| 9 | 8 | 3ad2ant3 |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> N e. NN0 ) | 
						
							| 10 |  | eleq1 |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( ( # ` ( 1st ` c ) ) e. NN0 <-> N e. NN0 ) ) | 
						
							| 11 | 10 | 3ad2ant1 |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( ( # ` ( 1st ` c ) ) e. NN0 <-> N e. NN0 ) ) | 
						
							| 12 | 9 11 | mpbird |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( # ` ( 1st ` c ) ) e. NN0 ) | 
						
							| 13 |  | nn0fz0 |  |-  ( ( # ` ( 1st ` c ) ) e. NN0 <-> ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 1st ` c ) ) ) ) | 
						
							| 14 | 12 13 | sylib |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 1st ` c ) ) ) ) | 
						
							| 15 |  | fzelp1 |  |-  ( ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 1st ` c ) ) ) -> ( # ` ( 1st ` c ) ) e. ( 0 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 16 | 14 15 | syl |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( # ` ( 1st ` c ) ) e. ( 0 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 17 |  | wlklenvp1 |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( # ` ( 2nd ` c ) ) = ( ( # ` ( 1st ` c ) ) + 1 ) ) | 
						
							| 18 | 17 | eqcomd |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( ( # ` ( 1st ` c ) ) + 1 ) = ( # ` ( 2nd ` c ) ) ) | 
						
							| 19 | 3 18 | syl |  |-  ( c e. ( ClWalks ` G ) -> ( ( # ` ( 1st ` c ) ) + 1 ) = ( # ` ( 2nd ` c ) ) ) | 
						
							| 20 | 19 | oveq2d |  |-  ( c e. ( ClWalks ` G ) -> ( 0 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) = ( 0 ... ( # ` ( 2nd ` c ) ) ) ) | 
						
							| 21 | 20 | eleq2d |  |-  ( c e. ( ClWalks ` G ) -> ( ( # ` ( 1st ` c ) ) e. ( 0 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) <-> ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 2nd ` c ) ) ) ) ) | 
						
							| 22 | 21 | 3ad2ant2 |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( ( # ` ( 1st ` c ) ) e. ( 0 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) <-> ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 2nd ` c ) ) ) ) ) | 
						
							| 23 | 16 22 | mpbid |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 2nd ` c ) ) ) ) | 
						
							| 24 |  | 2nn |  |-  2 e. NN | 
						
							| 25 | 24 | a1i |  |-  ( N e. ( ZZ>= ` 2 ) -> 2 e. NN ) | 
						
							| 26 |  | eluz2nn |  |-  ( N e. ( ZZ>= ` 2 ) -> N e. NN ) | 
						
							| 27 |  | eluzle |  |-  ( N e. ( ZZ>= ` 2 ) -> 2 <_ N ) | 
						
							| 28 |  | elfz1b |  |-  ( 2 e. ( 1 ... N ) <-> ( 2 e. NN /\ N e. NN /\ 2 <_ N ) ) | 
						
							| 29 | 25 26 27 28 | syl3anbrc |  |-  ( N e. ( ZZ>= ` 2 ) -> 2 e. ( 1 ... N ) ) | 
						
							| 30 |  | ubmelfzo |  |-  ( 2 e. ( 1 ... N ) -> ( N - 2 ) e. ( 0 ..^ N ) ) | 
						
							| 31 | 29 30 | syl |  |-  ( N e. ( ZZ>= ` 2 ) -> ( N - 2 ) e. ( 0 ..^ N ) ) | 
						
							| 32 | 31 | 3ad2ant3 |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( N - 2 ) e. ( 0 ..^ N ) ) | 
						
							| 33 |  | oveq2 |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( 0 ..^ ( # ` ( 1st ` c ) ) ) = ( 0 ..^ N ) ) | 
						
							| 34 | 33 | eleq2d |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( ( N - 2 ) e. ( 0 ..^ ( # ` ( 1st ` c ) ) ) <-> ( N - 2 ) e. ( 0 ..^ N ) ) ) | 
						
							| 35 | 34 | 3ad2ant1 |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( ( N - 2 ) e. ( 0 ..^ ( # ` ( 1st ` c ) ) ) <-> ( N - 2 ) e. ( 0 ..^ N ) ) ) | 
						
							| 36 | 32 35 | mpbird |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( N - 2 ) e. ( 0 ..^ ( # ` ( 1st ` c ) ) ) ) | 
						
							| 37 |  | pfxfv |  |-  ( ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 0 ... ( # ` ( 2nd ` c ) ) ) /\ ( N - 2 ) e. ( 0 ..^ ( # ` ( 1st ` c ) ) ) ) -> ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` ( N - 2 ) ) = ( ( 2nd ` c ) ` ( N - 2 ) ) ) | 
						
							| 38 | 7 23 36 37 | syl3anc |  |-  ( ( ( # ` ( 1st ` c ) ) = N /\ c e. ( ClWalks ` G ) /\ N e. ( ZZ>= ` 2 ) ) -> ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` ( N - 2 ) ) = ( ( 2nd ` c ) ` ( N - 2 ) ) ) |