| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mapdval.h |  | 
						
							| 2 |  | elex |  | 
						
							| 3 |  | fveq2 |  | 
						
							| 4 | 3 1 | eqtr4di |  | 
						
							| 5 |  | fveq2 |  | 
						
							| 6 | 5 | fveq1d |  | 
						
							| 7 | 6 | fveq2d |  | 
						
							| 8 | 6 | fveq2d |  | 
						
							| 9 |  | fveq2 |  | 
						
							| 10 | 9 | fveq1d |  | 
						
							| 11 | 6 | fveq2d |  | 
						
							| 12 | 11 | fveq1d |  | 
						
							| 13 | 10 12 | fveq12d |  | 
						
							| 14 | 10 13 | fveq12d |  | 
						
							| 15 | 14 12 | eqeq12d |  | 
						
							| 16 | 13 | sseq1d |  | 
						
							| 17 | 15 16 | anbi12d |  | 
						
							| 18 | 8 17 | rabeqbidv |  | 
						
							| 19 | 7 18 | mpteq12dv |  | 
						
							| 20 | 4 19 | mpteq12dv |  | 
						
							| 21 |  | df-mapd |  | 
						
							| 22 | 20 21 1 | mptfvmpt |  | 
						
							| 23 | 2 22 | syl |  |