| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ttrclselem.1 |  |-  F = rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) | 
						
							| 2 |  | nn0suc |  |-  ( N e. _om -> ( N = (/) \/ E. n e. _om N = suc n ) ) | 
						
							| 3 | 1 | fveq1i |  |-  ( F ` N ) = ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` N ) | 
						
							| 4 |  | fveq2 |  |-  ( N = (/) -> ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` N ) = ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) ) | 
						
							| 5 | 3 4 | eqtrid |  |-  ( N = (/) -> ( F ` N ) = ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) ) | 
						
							| 6 |  | rdg0g |  |-  ( Pred ( R , A , X ) e. _V -> ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) = Pred ( R , A , X ) ) | 
						
							| 7 |  | predss |  |-  Pred ( R , A , X ) C_ A | 
						
							| 8 | 6 7 | eqsstrdi |  |-  ( Pred ( R , A , X ) e. _V -> ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) C_ A ) | 
						
							| 9 |  | rdg0n |  |-  ( -. Pred ( R , A , X ) e. _V -> ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) = (/) ) | 
						
							| 10 |  | 0ss |  |-  (/) C_ A | 
						
							| 11 | 9 10 | eqsstrdi |  |-  ( -. Pred ( R , A , X ) e. _V -> ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) C_ A ) | 
						
							| 12 | 8 11 | pm2.61i |  |-  ( rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) ` (/) ) C_ A | 
						
							| 13 | 5 12 | eqsstrdi |  |-  ( N = (/) -> ( F ` N ) C_ A ) | 
						
							| 14 |  | nnon |  |-  ( n e. _om -> n e. On ) | 
						
							| 15 |  | nfcv |  |-  F/_ b Pred ( R , A , X ) | 
						
							| 16 |  | nfcv |  |-  F/_ b n | 
						
							| 17 |  | nfmpt1 |  |-  F/_ b ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) | 
						
							| 18 | 17 15 | nfrdg |  |-  F/_ b rec ( ( b e. _V |-> U_ w e. b Pred ( R , A , w ) ) , Pred ( R , A , X ) ) | 
						
							| 19 | 1 18 | nfcxfr |  |-  F/_ b F | 
						
							| 20 | 19 16 | nffv |  |-  F/_ b ( F ` n ) | 
						
							| 21 |  | nfcv |  |-  F/_ b Pred ( R , A , t ) | 
						
							| 22 | 20 21 | nfiun |  |-  F/_ b U_ t e. ( F ` n ) Pred ( R , A , t ) | 
						
							| 23 |  | predeq3 |  |-  ( w = t -> Pred ( R , A , w ) = Pred ( R , A , t ) ) | 
						
							| 24 | 23 | cbviunv |  |-  U_ w e. b Pred ( R , A , w ) = U_ t e. b Pred ( R , A , t ) | 
						
							| 25 |  | iuneq1 |  |-  ( b = ( F ` n ) -> U_ t e. b Pred ( R , A , t ) = U_ t e. ( F ` n ) Pred ( R , A , t ) ) | 
						
							| 26 | 24 25 | eqtrid |  |-  ( b = ( F ` n ) -> U_ w e. b Pred ( R , A , w ) = U_ t e. ( F ` n ) Pred ( R , A , t ) ) | 
						
							| 27 | 15 16 22 1 26 | rdgsucmptf |  |-  ( ( n e. On /\ U_ t e. ( F ` n ) Pred ( R , A , t ) e. _V ) -> ( F ` suc n ) = U_ t e. ( F ` n ) Pred ( R , A , t ) ) | 
						
							| 28 |  | iunss |  |-  ( U_ t e. ( F ` n ) Pred ( R , A , t ) C_ A <-> A. t e. ( F ` n ) Pred ( R , A , t ) C_ A ) | 
						
							| 29 |  | predss |  |-  Pred ( R , A , t ) C_ A | 
						
							| 30 | 29 | a1i |  |-  ( t e. ( F ` n ) -> Pred ( R , A , t ) C_ A ) | 
						
							| 31 | 28 30 | mprgbir |  |-  U_ t e. ( F ` n ) Pred ( R , A , t ) C_ A | 
						
							| 32 | 27 31 | eqsstrdi |  |-  ( ( n e. On /\ U_ t e. ( F ` n ) Pred ( R , A , t ) e. _V ) -> ( F ` suc n ) C_ A ) | 
						
							| 33 | 14 32 | sylan |  |-  ( ( n e. _om /\ U_ t e. ( F ` n ) Pred ( R , A , t ) e. _V ) -> ( F ` suc n ) C_ A ) | 
						
							| 34 | 15 16 22 1 26 | rdgsucmptnf |  |-  ( -. U_ t e. ( F ` n ) Pred ( R , A , t ) e. _V -> ( F ` suc n ) = (/) ) | 
						
							| 35 | 34 10 | eqsstrdi |  |-  ( -. U_ t e. ( F ` n ) Pred ( R , A , t ) e. _V -> ( F ` suc n ) C_ A ) | 
						
							| 36 | 35 | adantl |  |-  ( ( n e. _om /\ -. U_ t e. ( F ` n ) Pred ( R , A , t ) e. _V ) -> ( F ` suc n ) C_ A ) | 
						
							| 37 | 33 36 | pm2.61dan |  |-  ( n e. _om -> ( F ` suc n ) C_ A ) | 
						
							| 38 |  | fveq2 |  |-  ( N = suc n -> ( F ` N ) = ( F ` suc n ) ) | 
						
							| 39 | 38 | sseq1d |  |-  ( N = suc n -> ( ( F ` N ) C_ A <-> ( F ` suc n ) C_ A ) ) | 
						
							| 40 | 37 39 | syl5ibrcom |  |-  ( n e. _om -> ( N = suc n -> ( F ` N ) C_ A ) ) | 
						
							| 41 | 40 | rexlimiv |  |-  ( E. n e. _om N = suc n -> ( F ` N ) C_ A ) | 
						
							| 42 | 13 41 | jaoi |  |-  ( ( N = (/) \/ E. n e. _om N = suc n ) -> ( F ` N ) C_ A ) | 
						
							| 43 | 2 42 | syl |  |-  ( N e. _om -> ( F ` N ) C_ A ) |