| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fdc1.1 |  |-  A e. _V | 
						
							| 2 |  | fdc1.2 |  |-  M e. ZZ | 
						
							| 3 |  | fdc1.3 |  |-  Z = ( ZZ>= ` M ) | 
						
							| 4 |  | fdc1.4 |  |-  N = ( M + 1 ) | 
						
							| 5 |  | fdc1.5 |  |-  ( a = ( f ` M ) -> ( ze <-> si ) ) | 
						
							| 6 |  | fdc1.6 |  |-  ( a = ( f ` ( k - 1 ) ) -> ( ph <-> ps ) ) | 
						
							| 7 |  | fdc1.7 |  |-  ( b = ( f ` k ) -> ( ps <-> ch ) ) | 
						
							| 8 |  | fdc1.8 |  |-  ( a = ( f ` n ) -> ( th <-> ta ) ) | 
						
							| 9 |  | fdc1.9 |  |-  ( et -> E. a e. A ze ) | 
						
							| 10 |  | fdc1.10 |  |-  ( et -> R Fr A ) | 
						
							| 11 |  | fdc1.11 |  |-  ( ( et /\ a e. A ) -> ( th \/ E. b e. A ph ) ) | 
						
							| 12 |  | fdc1.12 |  |-  ( ( ( et /\ ph ) /\ ( a e. A /\ b e. A ) ) -> b R a ) | 
						
							| 13 |  | eleq1w |  |-  ( c = a -> ( c e. A <-> a e. A ) ) | 
						
							| 14 | 13 | anbi2d |  |-  ( c = a -> ( ( et /\ c e. A ) <-> ( et /\ a e. A ) ) ) | 
						
							| 15 |  | sbceq2a |  |-  ( c = a -> ( [. c / a ]. ze <-> ze ) ) | 
						
							| 16 | 14 15 | anbi12d |  |-  ( c = a -> ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) <-> ( ( et /\ a e. A ) /\ ze ) ) ) | 
						
							| 17 | 16 | imbi1d |  |-  ( c = a -> ( ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) <-> ( ( ( et /\ a e. A ) /\ ze ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) ) ) | 
						
							| 18 |  | sbsbc |  |-  ( [ d / a ] ph <-> [. d / a ]. ph ) | 
						
							| 19 |  | nfv |  |-  F/ a ps | 
						
							| 20 | 19 6 | sbhypf |  |-  ( d = ( f ` ( k - 1 ) ) -> ( [ d / a ] ph <-> ps ) ) | 
						
							| 21 | 18 20 | bitr3id |  |-  ( d = ( f ` ( k - 1 ) ) -> ( [. d / a ]. ph <-> ps ) ) | 
						
							| 22 |  | sbsbc |  |-  ( [ d / a ] th <-> [. d / a ]. th ) | 
						
							| 23 |  | nfv |  |-  F/ a ta | 
						
							| 24 | 23 8 | sbhypf |  |-  ( d = ( f ` n ) -> ( [ d / a ] th <-> ta ) ) | 
						
							| 25 | 22 24 | bitr3id |  |-  ( d = ( f ` n ) -> ( [. d / a ]. th <-> ta ) ) | 
						
							| 26 |  | simprl |  |-  ( ( et /\ ( c e. A /\ [. c / a ]. ze ) ) -> c e. A ) | 
						
							| 27 | 10 | adantr |  |-  ( ( et /\ ( c e. A /\ [. c / a ]. ze ) ) -> R Fr A ) | 
						
							| 28 |  | nfv |  |-  F/ a ( et /\ d e. A ) | 
						
							| 29 |  | nfsbc1v |  |-  F/ a [. d / a ]. th | 
						
							| 30 |  | nfcv |  |-  F/_ a A | 
						
							| 31 |  | nfsbc1v |  |-  F/ a [. d / a ]. ph | 
						
							| 32 | 30 31 | nfrexw |  |-  F/ a E. b e. A [. d / a ]. ph | 
						
							| 33 | 29 32 | nfor |  |-  F/ a ( [. d / a ]. th \/ E. b e. A [. d / a ]. ph ) | 
						
							| 34 | 28 33 | nfim |  |-  F/ a ( ( et /\ d e. A ) -> ( [. d / a ]. th \/ E. b e. A [. d / a ]. ph ) ) | 
						
							| 35 |  | eleq1w |  |-  ( a = d -> ( a e. A <-> d e. A ) ) | 
						
							| 36 | 35 | anbi2d |  |-  ( a = d -> ( ( et /\ a e. A ) <-> ( et /\ d e. A ) ) ) | 
						
							| 37 |  | sbceq1a |  |-  ( a = d -> ( th <-> [. d / a ]. th ) ) | 
						
							| 38 |  | sbceq1a |  |-  ( a = d -> ( ph <-> [. d / a ]. ph ) ) | 
						
							| 39 | 38 | rexbidv |  |-  ( a = d -> ( E. b e. A ph <-> E. b e. A [. d / a ]. ph ) ) | 
						
							| 40 | 37 39 | orbi12d |  |-  ( a = d -> ( ( th \/ E. b e. A ph ) <-> ( [. d / a ]. th \/ E. b e. A [. d / a ]. ph ) ) ) | 
						
							| 41 | 36 40 | imbi12d |  |-  ( a = d -> ( ( ( et /\ a e. A ) -> ( th \/ E. b e. A ph ) ) <-> ( ( et /\ d e. A ) -> ( [. d / a ]. th \/ E. b e. A [. d / a ]. ph ) ) ) ) | 
						
							| 42 | 34 41 11 | chvarfv |  |-  ( ( et /\ d e. A ) -> ( [. d / a ]. th \/ E. b e. A [. d / a ]. ph ) ) | 
						
							| 43 | 42 | adantlr |  |-  ( ( ( et /\ ( c e. A /\ [. c / a ]. ze ) ) /\ d e. A ) -> ( [. d / a ]. th \/ E. b e. A [. d / a ]. ph ) ) | 
						
							| 44 |  | nfv |  |-  F/ a et | 
						
							| 45 | 44 31 | nfan |  |-  F/ a ( et /\ [. d / a ]. ph ) | 
						
							| 46 |  | nfv |  |-  F/ a ( d e. A /\ b e. A ) | 
						
							| 47 | 45 46 | nfan |  |-  F/ a ( ( et /\ [. d / a ]. ph ) /\ ( d e. A /\ b e. A ) ) | 
						
							| 48 |  | nfv |  |-  F/ a b R d | 
						
							| 49 | 47 48 | nfim |  |-  F/ a ( ( ( et /\ [. d / a ]. ph ) /\ ( d e. A /\ b e. A ) ) -> b R d ) | 
						
							| 50 | 38 | anbi2d |  |-  ( a = d -> ( ( et /\ ph ) <-> ( et /\ [. d / a ]. ph ) ) ) | 
						
							| 51 | 35 | anbi1d |  |-  ( a = d -> ( ( a e. A /\ b e. A ) <-> ( d e. A /\ b e. A ) ) ) | 
						
							| 52 | 50 51 | anbi12d |  |-  ( a = d -> ( ( ( et /\ ph ) /\ ( a e. A /\ b e. A ) ) <-> ( ( et /\ [. d / a ]. ph ) /\ ( d e. A /\ b e. A ) ) ) ) | 
						
							| 53 |  | breq2 |  |-  ( a = d -> ( b R a <-> b R d ) ) | 
						
							| 54 | 52 53 | imbi12d |  |-  ( a = d -> ( ( ( ( et /\ ph ) /\ ( a e. A /\ b e. A ) ) -> b R a ) <-> ( ( ( et /\ [. d / a ]. ph ) /\ ( d e. A /\ b e. A ) ) -> b R d ) ) ) | 
						
							| 55 | 49 54 12 | chvarfv |  |-  ( ( ( et /\ [. d / a ]. ph ) /\ ( d e. A /\ b e. A ) ) -> b R d ) | 
						
							| 56 | 55 | adantllr |  |-  ( ( ( ( et /\ ( c e. A /\ [. c / a ]. ze ) ) /\ [. d / a ]. ph ) /\ ( d e. A /\ b e. A ) ) -> b R d ) | 
						
							| 57 | 1 2 3 4 21 7 25 26 27 43 56 | fdc |  |-  ( ( et /\ ( c e. A /\ [. c / a ]. ze ) ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( ( f ` M ) = c /\ ta ) /\ A. k e. ( N ... n ) ch ) ) | 
						
							| 58 | 57 | anassrs |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( ( f ` M ) = c /\ ta ) /\ A. k e. ( N ... n ) ch ) ) | 
						
							| 59 |  | idd |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( f : ( M ... n ) --> A -> f : ( M ... n ) --> A ) ) | 
						
							| 60 |  | dfsbcq |  |-  ( ( f ` M ) = c -> ( [. ( f ` M ) / a ]. ze <-> [. c / a ]. ze ) ) | 
						
							| 61 |  | fvex |  |-  ( f ` M ) e. _V | 
						
							| 62 | 61 5 | sbcie |  |-  ( [. ( f ` M ) / a ]. ze <-> si ) | 
						
							| 63 | 60 62 | bitr3di |  |-  ( ( f ` M ) = c -> ( [. c / a ]. ze <-> si ) ) | 
						
							| 64 | 63 | biimpcd |  |-  ( [. c / a ]. ze -> ( ( f ` M ) = c -> si ) ) | 
						
							| 65 | 64 | adantl |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( ( f ` M ) = c -> si ) ) | 
						
							| 66 | 65 | anim1d |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( ( ( f ` M ) = c /\ ta ) -> ( si /\ ta ) ) ) | 
						
							| 67 |  | idd |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( A. k e. ( N ... n ) ch -> A. k e. ( N ... n ) ch ) ) | 
						
							| 68 | 59 66 67 | 3anim123d |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( ( f : ( M ... n ) --> A /\ ( ( f ` M ) = c /\ ta ) /\ A. k e. ( N ... n ) ch ) -> ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) ) | 
						
							| 69 | 68 | eximdv |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( E. f ( f : ( M ... n ) --> A /\ ( ( f ` M ) = c /\ ta ) /\ A. k e. ( N ... n ) ch ) -> E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) ) | 
						
							| 70 | 69 | reximdv |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> ( E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( ( f ` M ) = c /\ ta ) /\ A. k e. ( N ... n ) ch ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) ) | 
						
							| 71 | 58 70 | mpd |  |-  ( ( ( et /\ c e. A ) /\ [. c / a ]. ze ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) | 
						
							| 72 | 17 71 | chvarvv |  |-  ( ( ( et /\ a e. A ) /\ ze ) -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) | 
						
							| 73 | 72 9 | r19.29a |  |-  ( et -> E. n e. Z E. f ( f : ( M ... n ) --> A /\ ( si /\ ta ) /\ A. k e. ( N ... n ) ch ) ) |