| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							bnj1121.1 | 
							 |-  ( th <-> ( R _FrSe A /\ X e. A ) )  | 
						
						
							| 2 | 
							
								
							 | 
							bnj1121.2 | 
							 |-  ( ta <-> ( B e. _V /\ _TrFo ( B , A , R ) /\ _pred ( X , A , R ) C_ B ) )  | 
						
						
							| 3 | 
							
								
							 | 
							bnj1121.3 | 
							 |-  ( ch <-> ( n e. D /\ f Fn n /\ ph /\ ps ) )  | 
						
						
							| 4 | 
							
								
							 | 
							bnj1121.4 | 
							 |-  ( ze <-> ( i e. n /\ z e. ( f ` i ) ) )  | 
						
						
							| 5 | 
							
								
							 | 
							bnj1121.5 | 
							 |-  ( et <-> ( ( f e. K /\ i e. dom f ) -> ( f ` i ) C_ B ) )  | 
						
						
							| 6 | 
							
								
							 | 
							bnj1121.6 | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> A. i e. n et )  | 
						
						
							| 7 | 
							
								
							 | 
							bnj1121.7 | 
							 |-  K = { f | E. n e. D ( f Fn n /\ ph /\ ps ) } | 
						
						
							| 8 | 
							
								
							 | 
							19.8a | 
							 |-  ( ch -> E. n ch )  | 
						
						
							| 9 | 
							
								8
							 | 
							bnj707 | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> E. n ch )  | 
						
						
							| 10 | 
							
								3 7
							 | 
							bnj1083 | 
							 |-  ( f e. K <-> E. n ch )  | 
						
						
							| 11 | 
							
								9 10
							 | 
							sylibr | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> f e. K )  | 
						
						
							| 12 | 
							
								4
							 | 
							simplbi | 
							 |-  ( ze -> i e. n )  | 
						
						
							| 13 | 
							
								12
							 | 
							bnj708 | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> i e. n )  | 
						
						
							| 14 | 
							
								3
							 | 
							bnj1235 | 
							 |-  ( ch -> f Fn n )  | 
						
						
							| 15 | 
							
								14
							 | 
							bnj707 | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> f Fn n )  | 
						
						
							| 16 | 
							
								15
							 | 
							fndmd | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> dom f = n )  | 
						
						
							| 17 | 
							
								13 16
							 | 
							eleqtrrd | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> i e. dom f )  | 
						
						
							| 18 | 
							
								6 13
							 | 
							bnj1294 | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> et )  | 
						
						
							| 19 | 
							
								18 5
							 | 
							sylib | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> ( ( f e. K /\ i e. dom f ) -> ( f ` i ) C_ B ) )  | 
						
						
							| 20 | 
							
								11 17 19
							 | 
							mp2and | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> ( f ` i ) C_ B )  | 
						
						
							| 21 | 
							
								4
							 | 
							simprbi | 
							 |-  ( ze -> z e. ( f ` i ) )  | 
						
						
							| 22 | 
							
								21
							 | 
							bnj708 | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> z e. ( f ` i ) )  | 
						
						
							| 23 | 
							
								20 22
							 | 
							sseldd | 
							 |-  ( ( th /\ ta /\ ch /\ ze ) -> z e. B )  |