| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dibval.b |  | 
						
							| 2 |  | dibval.h |  | 
						
							| 3 |  | dibval.t |  | 
						
							| 4 |  | dibval.o |  | 
						
							| 5 |  | dibval.j |  | 
						
							| 6 |  | dibval.i |  | 
						
							| 7 | 1 2 | dibffval |  | 
						
							| 8 | 7 | fveq1d |  | 
						
							| 9 | 6 8 | eqtrid |  | 
						
							| 10 |  | fveq2 |  | 
						
							| 11 | 10 5 | eqtr4di |  | 
						
							| 12 | 11 | dmeqd |  | 
						
							| 13 | 11 | fveq1d |  | 
						
							| 14 |  | fveq2 |  | 
						
							| 15 | 14 3 | eqtr4di |  | 
						
							| 16 |  | eqidd |  | 
						
							| 17 | 15 16 | mpteq12dv |  | 
						
							| 18 | 17 4 | eqtr4di |  | 
						
							| 19 | 18 | sneqd |  | 
						
							| 20 | 13 19 | xpeq12d |  | 
						
							| 21 | 12 20 | mpteq12dv |  | 
						
							| 22 |  | eqid |  | 
						
							| 23 | 5 | fvexi |  | 
						
							| 24 | 23 | dmex |  | 
						
							| 25 | 24 | mptex |  | 
						
							| 26 | 21 22 25 | fvmpt |  | 
						
							| 27 | 9 26 | sylan9eq |  |