| Step | Hyp | Ref | Expression | 
						
							| 1 |  | clwwlknonclwlknonf1o.v |  |-  V = ( Vtx ` G ) | 
						
							| 2 |  | clwwlknonclwlknonf1o.w |  |-  W = { w e. ( ClWalks ` G ) | ( ( # ` ( 1st ` w ) ) = N /\ ( ( 2nd ` w ) ` 0 ) = X ) } | 
						
							| 3 |  | clwwlknonclwlknonf1o.f |  |-  F = ( c e. W |-> ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) | 
						
							| 4 |  | eqid |  |-  { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } = { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } | 
						
							| 5 |  | eqid |  |-  ( c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } |-> ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) = ( c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } |-> ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) | 
						
							| 6 |  | eqid |  |-  ( 1st ` c ) = ( 1st ` c ) | 
						
							| 7 |  | eqid |  |-  ( 2nd ` c ) = ( 2nd ` c ) | 
						
							| 8 | 6 7 4 5 | clwlknf1oclwwlkn |  |-  ( ( G e. USPGraph /\ N e. NN ) -> ( c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } |-> ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) : { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } -1-1-onto-> ( N ClWWalksN G ) ) | 
						
							| 9 | 8 | 3adant2 |  |-  ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> ( c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } |-> ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) : { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } -1-1-onto-> ( N ClWWalksN G ) ) | 
						
							| 10 |  | fveq1 |  |-  ( s = ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) -> ( s ` 0 ) = ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` 0 ) ) | 
						
							| 11 | 10 | 3ad2ant3 |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } /\ s = ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) -> ( s ` 0 ) = ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` 0 ) ) | 
						
							| 12 |  | 2fveq3 |  |-  ( w = c -> ( # ` ( 1st ` w ) ) = ( # ` ( 1st ` c ) ) ) | 
						
							| 13 | 12 | eqeq1d |  |-  ( w = c -> ( ( # ` ( 1st ` w ) ) = N <-> ( # ` ( 1st ` c ) ) = N ) ) | 
						
							| 14 | 13 | elrab |  |-  ( c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } <-> ( c e. ( ClWalks ` G ) /\ ( # ` ( 1st ` c ) ) = N ) ) | 
						
							| 15 |  | clwlkwlk |  |-  ( c e. ( ClWalks ` G ) -> c e. ( Walks ` G ) ) | 
						
							| 16 |  | wlkcpr |  |-  ( c e. ( Walks ` G ) <-> ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) ) | 
						
							| 17 |  | eqid |  |-  ( Vtx ` G ) = ( Vtx ` G ) | 
						
							| 18 | 17 | wlkpwrd |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 19 | 18 | 3ad2ant1 |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 20 |  | elnnuz |  |-  ( N e. NN <-> N e. ( ZZ>= ` 1 ) ) | 
						
							| 21 |  | eluzfz2 |  |-  ( N e. ( ZZ>= ` 1 ) -> N e. ( 1 ... N ) ) | 
						
							| 22 | 20 21 | sylbi |  |-  ( N e. NN -> N e. ( 1 ... N ) ) | 
						
							| 23 |  | fzelp1 |  |-  ( N e. ( 1 ... N ) -> N e. ( 1 ... ( N + 1 ) ) ) | 
						
							| 24 | 22 23 | syl |  |-  ( N e. NN -> N e. ( 1 ... ( N + 1 ) ) ) | 
						
							| 25 | 24 | 3ad2ant3 |  |-  ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> N e. ( 1 ... ( N + 1 ) ) ) | 
						
							| 26 | 25 | 3ad2ant3 |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> N e. ( 1 ... ( N + 1 ) ) ) | 
						
							| 27 |  | id |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( # ` ( 1st ` c ) ) = N ) | 
						
							| 28 |  | oveq1 |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( ( # ` ( 1st ` c ) ) + 1 ) = ( N + 1 ) ) | 
						
							| 29 | 28 | oveq2d |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) = ( 1 ... ( N + 1 ) ) ) | 
						
							| 30 | 27 29 | eleq12d |  |-  ( ( # ` ( 1st ` c ) ) = N -> ( ( # ` ( 1st ` c ) ) e. ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) <-> N e. ( 1 ... ( N + 1 ) ) ) ) | 
						
							| 31 | 30 | 3ad2ant2 |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> ( ( # ` ( 1st ` c ) ) e. ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) <-> N e. ( 1 ... ( N + 1 ) ) ) ) | 
						
							| 32 | 26 31 | mpbird |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> ( # ` ( 1st ` c ) ) e. ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 33 |  | wlklenvp1 |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( # ` ( 2nd ` c ) ) = ( ( # ` ( 1st ` c ) ) + 1 ) ) | 
						
							| 34 | 33 | oveq2d |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( 1 ... ( # ` ( 2nd ` c ) ) ) = ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 35 | 34 | eleq2d |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) <-> ( # ` ( 1st ` c ) ) e. ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) ) ) | 
						
							| 36 | 35 | 3ad2ant1 |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> ( ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) <-> ( # ` ( 1st ` c ) ) e. ( 1 ... ( ( # ` ( 1st ` c ) ) + 1 ) ) ) ) | 
						
							| 37 | 32 36 | mpbird |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) | 
						
							| 38 | 19 37 | jca |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) = N /\ ( G e. USPGraph /\ X e. V /\ N e. NN ) ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) | 
						
							| 39 | 38 | 3exp |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( ( # ` ( 1st ` c ) ) = N -> ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) ) ) | 
						
							| 40 | 16 39 | sylbi |  |-  ( c e. ( Walks ` G ) -> ( ( # ` ( 1st ` c ) ) = N -> ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) ) ) | 
						
							| 41 | 15 40 | syl |  |-  ( c e. ( ClWalks ` G ) -> ( ( # ` ( 1st ` c ) ) = N -> ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) ) ) | 
						
							| 42 | 41 | imp |  |-  ( ( c e. ( ClWalks ` G ) /\ ( # ` ( 1st ` c ) ) = N ) -> ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) ) | 
						
							| 43 | 14 42 | sylbi |  |-  ( c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } -> ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) ) | 
						
							| 44 | 43 | impcom |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } ) -> ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) ) | 
						
							| 45 |  | pfxfv0 |  |-  ( ( ( 2nd ` c ) e. Word ( Vtx ` G ) /\ ( # ` ( 1st ` c ) ) e. ( 1 ... ( # ` ( 2nd ` c ) ) ) ) -> ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` 0 ) = ( ( 2nd ` c ) ` 0 ) ) | 
						
							| 46 | 44 45 | syl |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } ) -> ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` 0 ) = ( ( 2nd ` c ) ` 0 ) ) | 
						
							| 47 | 46 | 3adant3 |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } /\ s = ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) -> ( ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ` 0 ) = ( ( 2nd ` c ) ` 0 ) ) | 
						
							| 48 | 11 47 | eqtrd |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } /\ s = ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) -> ( s ` 0 ) = ( ( 2nd ` c ) ` 0 ) ) | 
						
							| 49 | 48 | eqeq1d |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } /\ s = ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) -> ( ( s ` 0 ) = X <-> ( ( 2nd ` c ) ` 0 ) = X ) ) | 
						
							| 50 |  | nfv |  |-  F/ w ( ( 2nd ` c ) ` 0 ) = X | 
						
							| 51 |  | fveq2 |  |-  ( w = c -> ( 2nd ` w ) = ( 2nd ` c ) ) | 
						
							| 52 | 51 | fveq1d |  |-  ( w = c -> ( ( 2nd ` w ) ` 0 ) = ( ( 2nd ` c ) ` 0 ) ) | 
						
							| 53 | 52 | eqeq1d |  |-  ( w = c -> ( ( ( 2nd ` w ) ` 0 ) = X <-> ( ( 2nd ` c ) ` 0 ) = X ) ) | 
						
							| 54 | 50 53 | sbiev |  |-  ( [ c / w ] ( ( 2nd ` w ) ` 0 ) = X <-> ( ( 2nd ` c ) ` 0 ) = X ) | 
						
							| 55 | 49 54 | bitr4di |  |-  ( ( ( G e. USPGraph /\ X e. V /\ N e. NN ) /\ c e. { w e. ( ClWalks ` G ) | ( # ` ( 1st ` w ) ) = N } /\ s = ( ( 2nd ` c ) prefix ( # ` ( 1st ` c ) ) ) ) -> ( ( s ` 0 ) = X <-> [ c / w ] ( ( 2nd ` w ) ` 0 ) = X ) ) | 
						
							| 56 | 2 4 3 5 9 55 | f1ossf1o |  |-  ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> F : W -1-1-onto-> { s e. ( N ClWWalksN G ) | ( s ` 0 ) = X } ) | 
						
							| 57 |  | clwwlknon |  |-  ( X ( ClWWalksNOn ` G ) N ) = { s e. ( N ClWWalksN G ) | ( s ` 0 ) = X } | 
						
							| 58 |  | f1oeq3 |  |-  ( ( X ( ClWWalksNOn ` G ) N ) = { s e. ( N ClWWalksN G ) | ( s ` 0 ) = X } -> ( F : W -1-1-onto-> ( X ( ClWWalksNOn ` G ) N ) <-> F : W -1-1-onto-> { s e. ( N ClWWalksN G ) | ( s ` 0 ) = X } ) ) | 
						
							| 59 | 57 58 | ax-mp |  |-  ( F : W -1-1-onto-> ( X ( ClWWalksNOn ` G ) N ) <-> F : W -1-1-onto-> { s e. ( N ClWWalksN G ) | ( s ` 0 ) = X } ) | 
						
							| 60 | 56 59 | sylibr |  |-  ( ( G e. USPGraph /\ X e. V /\ N e. NN ) -> F : W -1-1-onto-> ( X ( ClWWalksNOn ` G ) N ) ) |