| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nfwrecsOLD.1 |  |-  F/_ x R | 
						
							| 2 |  | nfwrecsOLD.2 |  |-  F/_ x A | 
						
							| 3 |  | nfwrecsOLD.3 |  |-  F/_ x F | 
						
							| 4 |  | dfwrecsOLD |  |-  wrecs ( R , A , F ) = U. { f | E. y ( f Fn y /\ ( y C_ A /\ A. z e. y Pred ( R , A , z ) C_ y ) /\ A. z e. y ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) ) } | 
						
							| 5 |  | nfv |  |-  F/ x f Fn y | 
						
							| 6 |  | nfcv |  |-  F/_ x y | 
						
							| 7 | 6 2 | nfss |  |-  F/ x y C_ A | 
						
							| 8 |  | nfcv |  |-  F/_ x z | 
						
							| 9 | 1 2 8 | nfpred |  |-  F/_ x Pred ( R , A , z ) | 
						
							| 10 | 9 6 | nfss |  |-  F/ x Pred ( R , A , z ) C_ y | 
						
							| 11 | 6 10 | nfralw |  |-  F/ x A. z e. y Pred ( R , A , z ) C_ y | 
						
							| 12 | 7 11 | nfan |  |-  F/ x ( y C_ A /\ A. z e. y Pred ( R , A , z ) C_ y ) | 
						
							| 13 |  | nfcv |  |-  F/_ x f | 
						
							| 14 | 13 9 | nfres |  |-  F/_ x ( f |` Pred ( R , A , z ) ) | 
						
							| 15 | 3 14 | nffv |  |-  F/_ x ( F ` ( f |` Pred ( R , A , z ) ) ) | 
						
							| 16 | 15 | nfeq2 |  |-  F/ x ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) | 
						
							| 17 | 6 16 | nfralw |  |-  F/ x A. z e. y ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) | 
						
							| 18 | 5 12 17 | nf3an |  |-  F/ x ( f Fn y /\ ( y C_ A /\ A. z e. y Pred ( R , A , z ) C_ y ) /\ A. z e. y ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) ) | 
						
							| 19 | 18 | nfex |  |-  F/ x E. y ( f Fn y /\ ( y C_ A /\ A. z e. y Pred ( R , A , z ) C_ y ) /\ A. z e. y ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) ) | 
						
							| 20 | 19 | nfab |  |-  F/_ x { f | E. y ( f Fn y /\ ( y C_ A /\ A. z e. y Pred ( R , A , z ) C_ y ) /\ A. z e. y ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) ) } | 
						
							| 21 | 20 | nfuni |  |-  F/_ x U. { f | E. y ( f Fn y /\ ( y C_ A /\ A. z e. y Pred ( R , A , z ) C_ y ) /\ A. z e. y ( f ` z ) = ( F ` ( f |` Pred ( R , A , z ) ) ) ) } | 
						
							| 22 | 4 21 | nfcxfr |  |-  F/_ x wrecs ( R , A , F ) |