| Step | Hyp | Ref | Expression | 
						
							| 1 |  | clwlkclwwlkf.c |  |-  C = { w e. ( ClWalks ` G ) | 1 <_ ( # ` ( 1st ` w ) ) } | 
						
							| 2 |  | clwlkclwwlkf.f |  |-  F = ( c e. C |-> ( ( 2nd ` c ) prefix ( ( # ` ( 2nd ` c ) ) - 1 ) ) ) | 
						
							| 3 |  | eqid |  |-  ( 1st ` c ) = ( 1st ` c ) | 
						
							| 4 |  | eqid |  |-  ( 2nd ` c ) = ( 2nd ` c ) | 
						
							| 5 | 1 3 4 | clwlkclwwlkflem |  |-  ( c e. C -> ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) | 
						
							| 6 |  | isclwlk |  |-  ( ( 1st ` c ) ( ClWalks ` G ) ( 2nd ` c ) <-> ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) ) ) | 
						
							| 7 |  | fvex |  |-  ( 1st ` c ) e. _V | 
						
							| 8 |  | breq1 |  |-  ( f = ( 1st ` c ) -> ( f ( ClWalks ` G ) ( 2nd ` c ) <-> ( 1st ` c ) ( ClWalks ` G ) ( 2nd ` c ) ) ) | 
						
							| 9 | 7 8 | spcev |  |-  ( ( 1st ` c ) ( ClWalks ` G ) ( 2nd ` c ) -> E. f f ( ClWalks ` G ) ( 2nd ` c ) ) | 
						
							| 10 | 6 9 | sylbir |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) ) -> E. f f ( ClWalks ` G ) ( 2nd ` c ) ) | 
						
							| 11 | 10 | 3adant3 |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) -> E. f f ( ClWalks ` G ) ( 2nd ` c ) ) | 
						
							| 12 | 11 | adantl |  |-  ( ( G e. USPGraph /\ ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) -> E. f f ( ClWalks ` G ) ( 2nd ` c ) ) | 
						
							| 13 |  | simpl |  |-  ( ( G e. USPGraph /\ ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) -> G e. USPGraph ) | 
						
							| 14 |  | eqid |  |-  ( Vtx ` G ) = ( Vtx ` G ) | 
						
							| 15 | 14 | wlkpwrd |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 16 | 15 | 3ad2ant1 |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 17 | 16 | adantl |  |-  ( ( G e. USPGraph /\ ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) -> ( 2nd ` c ) e. Word ( Vtx ` G ) ) | 
						
							| 18 |  | elnnnn0c |  |-  ( ( # ` ( 1st ` c ) ) e. NN <-> ( ( # ` ( 1st ` c ) ) e. NN0 /\ 1 <_ ( # ` ( 1st ` c ) ) ) ) | 
						
							| 19 |  | nn0re |  |-  ( ( # ` ( 1st ` c ) ) e. NN0 -> ( # ` ( 1st ` c ) ) e. RR ) | 
						
							| 20 |  | 1e2m1 |  |-  1 = ( 2 - 1 ) | 
						
							| 21 | 20 | breq1i |  |-  ( 1 <_ ( # ` ( 1st ` c ) ) <-> ( 2 - 1 ) <_ ( # ` ( 1st ` c ) ) ) | 
						
							| 22 | 21 | biimpi |  |-  ( 1 <_ ( # ` ( 1st ` c ) ) -> ( 2 - 1 ) <_ ( # ` ( 1st ` c ) ) ) | 
						
							| 23 |  | 2re |  |-  2 e. RR | 
						
							| 24 |  | 1re |  |-  1 e. RR | 
						
							| 25 |  | lesubadd |  |-  ( ( 2 e. RR /\ 1 e. RR /\ ( # ` ( 1st ` c ) ) e. RR ) -> ( ( 2 - 1 ) <_ ( # ` ( 1st ` c ) ) <-> 2 <_ ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 26 | 23 24 25 | mp3an12 |  |-  ( ( # ` ( 1st ` c ) ) e. RR -> ( ( 2 - 1 ) <_ ( # ` ( 1st ` c ) ) <-> 2 <_ ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 27 | 22 26 | imbitrid |  |-  ( ( # ` ( 1st ` c ) ) e. RR -> ( 1 <_ ( # ` ( 1st ` c ) ) -> 2 <_ ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 28 | 19 27 | syl |  |-  ( ( # ` ( 1st ` c ) ) e. NN0 -> ( 1 <_ ( # ` ( 1st ` c ) ) -> 2 <_ ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 29 | 28 | adantl |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) e. NN0 ) -> ( 1 <_ ( # ` ( 1st ` c ) ) -> 2 <_ ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 30 |  | wlklenvp1 |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( # ` ( 2nd ` c ) ) = ( ( # ` ( 1st ` c ) ) + 1 ) ) | 
						
							| 31 | 30 | adantr |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) e. NN0 ) -> ( # ` ( 2nd ` c ) ) = ( ( # ` ( 1st ` c ) ) + 1 ) ) | 
						
							| 32 | 31 | breq2d |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) e. NN0 ) -> ( 2 <_ ( # ` ( 2nd ` c ) ) <-> 2 <_ ( ( # ` ( 1st ` c ) ) + 1 ) ) ) | 
						
							| 33 | 29 32 | sylibrd |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( # ` ( 1st ` c ) ) e. NN0 ) -> ( 1 <_ ( # ` ( 1st ` c ) ) -> 2 <_ ( # ` ( 2nd ` c ) ) ) ) | 
						
							| 34 | 33 | expimpd |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( ( ( # ` ( 1st ` c ) ) e. NN0 /\ 1 <_ ( # ` ( 1st ` c ) ) ) -> 2 <_ ( # ` ( 2nd ` c ) ) ) ) | 
						
							| 35 | 18 34 | biimtrid |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( ( # ` ( 1st ` c ) ) e. NN -> 2 <_ ( # ` ( 2nd ` c ) ) ) ) | 
						
							| 36 | 35 | a1d |  |-  ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) -> ( ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) -> ( ( # ` ( 1st ` c ) ) e. NN -> 2 <_ ( # ` ( 2nd ` c ) ) ) ) ) | 
						
							| 37 | 36 | 3imp |  |-  ( ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) -> 2 <_ ( # ` ( 2nd ` c ) ) ) | 
						
							| 38 | 37 | adantl |  |-  ( ( G e. USPGraph /\ ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) -> 2 <_ ( # ` ( 2nd ` c ) ) ) | 
						
							| 39 |  | eqid |  |-  ( iEdg ` G ) = ( iEdg ` G ) | 
						
							| 40 | 14 39 | clwlkclwwlk |  |-  ( ( G e. USPGraph /\ ( 2nd ` c ) e. Word ( Vtx ` G ) /\ 2 <_ ( # ` ( 2nd ` c ) ) ) -> ( E. f f ( ClWalks ` G ) ( 2nd ` c ) <-> ( ( lastS ` ( 2nd ` c ) ) = ( ( 2nd ` c ) ` 0 ) /\ ( ( 2nd ` c ) prefix ( ( # ` ( 2nd ` c ) ) - 1 ) ) e. ( ClWWalks ` G ) ) ) ) | 
						
							| 41 | 13 17 38 40 | syl3anc |  |-  ( ( G e. USPGraph /\ ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) -> ( E. f f ( ClWalks ` G ) ( 2nd ` c ) <-> ( ( lastS ` ( 2nd ` c ) ) = ( ( 2nd ` c ) ` 0 ) /\ ( ( 2nd ` c ) prefix ( ( # ` ( 2nd ` c ) ) - 1 ) ) e. ( ClWWalks ` G ) ) ) ) | 
						
							| 42 | 12 41 | mpbid |  |-  ( ( G e. USPGraph /\ ( ( 1st ` c ) ( Walks ` G ) ( 2nd ` c ) /\ ( ( 2nd ` c ) ` 0 ) = ( ( 2nd ` c ) ` ( # ` ( 1st ` c ) ) ) /\ ( # ` ( 1st ` c ) ) e. NN ) ) -> ( ( lastS ` ( 2nd ` c ) ) = ( ( 2nd ` c ) ` 0 ) /\ ( ( 2nd ` c ) prefix ( ( # ` ( 2nd ` c ) ) - 1 ) ) e. ( ClWWalks ` G ) ) ) | 
						
							| 43 | 5 42 | sylan2 |  |-  ( ( G e. USPGraph /\ c e. C ) -> ( ( lastS ` ( 2nd ` c ) ) = ( ( 2nd ` c ) ` 0 ) /\ ( ( 2nd ` c ) prefix ( ( # ` ( 2nd ` c ) ) - 1 ) ) e. ( ClWWalks ` G ) ) ) | 
						
							| 44 | 43 | simprd |  |-  ( ( G e. USPGraph /\ c e. C ) -> ( ( 2nd ` c ) prefix ( ( # ` ( 2nd ` c ) ) - 1 ) ) e. ( ClWWalks ` G ) ) | 
						
							| 45 | 44 2 | fmptd |  |-  ( G e. USPGraph -> F : C --> ( ClWWalks ` G ) ) |