| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							climrel | 
							 |-  Rel ~~>  | 
						
						
							| 2 | 
							
								
							 | 
							climuni | 
							 |-  ( ( x ~~> y /\ x ~~> z ) -> y = z )  | 
						
						
							| 3 | 
							
								2
							 | 
							ax-gen | 
							 |-  A. z ( ( x ~~> y /\ x ~~> z ) -> y = z )  | 
						
						
							| 4 | 
							
								3
							 | 
							ax-gen | 
							 |-  A. y A. z ( ( x ~~> y /\ x ~~> z ) -> y = z )  | 
						
						
							| 5 | 
							
								4
							 | 
							ax-gen | 
							 |-  A. x A. y A. z ( ( x ~~> y /\ x ~~> z ) -> y = z )  | 
						
						
							| 6 | 
							
								
							 | 
							dffun2 | 
							 |-  ( Fun ~~> <-> ( Rel ~~> /\ A. x A. y A. z ( ( x ~~> y /\ x ~~> z ) -> y = z ) ) )  | 
						
						
							| 7 | 
							
								1 5 6
							 | 
							mpbir2an | 
							 |-  Fun ~~>  | 
						
						
							| 8 | 
							
								
							 | 
							funfn | 
							 |-  ( Fun ~~> <-> ~~> Fn dom ~~> )  | 
						
						
							| 9 | 
							
								7 8
							 | 
							mpbi | 
							 |-  ~~> Fn dom ~~>  | 
						
						
							| 10 | 
							
								
							 | 
							vex | 
							 |-  y e. _V  | 
						
						
							| 11 | 
							
								10
							 | 
							elrn | 
							 |-  ( y e. ran ~~> <-> E. x x ~~> y )  | 
						
						
							| 12 | 
							
								
							 | 
							climcl | 
							 |-  ( x ~~> y -> y e. CC )  | 
						
						
							| 13 | 
							
								12
							 | 
							exlimiv | 
							 |-  ( E. x x ~~> y -> y e. CC )  | 
						
						
							| 14 | 
							
								11 13
							 | 
							sylbi | 
							 |-  ( y e. ran ~~> -> y e. CC )  | 
						
						
							| 15 | 
							
								14
							 | 
							ssriv | 
							 |-  ran ~~> C_ CC  | 
						
						
							| 16 | 
							
								
							 | 
							df-f | 
							 |-  ( ~~> : dom ~~> --> CC <-> ( ~~> Fn dom ~~> /\ ran ~~> C_ CC ) )  | 
						
						
							| 17 | 
							
								9 15 16
							 | 
							mpbir2an | 
							 |-  ~~> : dom ~~> --> CC  |