| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							homahom.h | 
							 |-  H = ( HomA ` C )  | 
						
						
							| 2 | 
							
								
							 | 
							xpss | 
							 |-  ( ( ( Base ` C ) X. ( Base ` C ) ) X. _V ) C_ ( _V X. _V )  | 
						
						
							| 3 | 
							
								
							 | 
							eqid | 
							 |-  ( Base ` C ) = ( Base ` C )  | 
						
						
							| 4 | 
							
								1
							 | 
							homarcl | 
							 |-  ( f e. ( X H Y ) -> C e. Cat )  | 
						
						
							| 5 | 
							
								1 3 4
							 | 
							homaf | 
							 |-  ( f e. ( X H Y ) -> H : ( ( Base ` C ) X. ( Base ` C ) ) --> ~P ( ( ( Base ` C ) X. ( Base ` C ) ) X. _V ) )  | 
						
						
							| 6 | 
							
								1 3
							 | 
							homarcl2 | 
							 |-  ( f e. ( X H Y ) -> ( X e. ( Base ` C ) /\ Y e. ( Base ` C ) ) )  | 
						
						
							| 7 | 
							
								6
							 | 
							simpld | 
							 |-  ( f e. ( X H Y ) -> X e. ( Base ` C ) )  | 
						
						
							| 8 | 
							
								6
							 | 
							simprd | 
							 |-  ( f e. ( X H Y ) -> Y e. ( Base ` C ) )  | 
						
						
							| 9 | 
							
								5 7 8
							 | 
							fovcdmd | 
							 |-  ( f e. ( X H Y ) -> ( X H Y ) e. ~P ( ( ( Base ` C ) X. ( Base ` C ) ) X. _V ) )  | 
						
						
							| 10 | 
							
								
							 | 
							elelpwi | 
							 |-  ( ( f e. ( X H Y ) /\ ( X H Y ) e. ~P ( ( ( Base ` C ) X. ( Base ` C ) ) X. _V ) ) -> f e. ( ( ( Base ` C ) X. ( Base ` C ) ) X. _V ) )  | 
						
						
							| 11 | 
							
								9 10
							 | 
							mpdan | 
							 |-  ( f e. ( X H Y ) -> f e. ( ( ( Base ` C ) X. ( Base ` C ) ) X. _V ) )  | 
						
						
							| 12 | 
							
								2 11
							 | 
							sselid | 
							 |-  ( f e. ( X H Y ) -> f e. ( _V X. _V ) )  | 
						
						
							| 13 | 
							
								12
							 | 
							ssriv | 
							 |-  ( X H Y ) C_ ( _V X. _V )  | 
						
						
							| 14 | 
							
								
							 | 
							df-rel | 
							 |-  ( Rel ( X H Y ) <-> ( X H Y ) C_ ( _V X. _V ) )  | 
						
						
							| 15 | 
							
								13 14
							 | 
							mpbir | 
							 |-  Rel ( X H Y )  |