| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eleq1 |  | 
						
							| 2 |  | dfatafv2rnb |  | 
						
							| 3 |  | dfdfat2 |  | 
						
							| 4 | 3 | simprbi |  | 
						
							| 5 | 2 4 | sylbir |  | 
						
							| 6 |  | tz6.12c-afv2 |  | 
						
							| 7 | 5 6 | syl |  | 
						
							| 8 | 7 | biimpcd |  | 
						
							| 9 | 1 8 | sylbird |  | 
						
							| 10 | 9 | eqcoms |  | 
						
							| 11 |  | eleq1 |  | 
						
							| 12 |  | breq2 |  | 
						
							| 13 | 10 11 12 | 3imtr3d |  | 
						
							| 14 | 13 | vtocleg |  | 
						
							| 15 | 14 | pm2.43i |  | 
						
							| 16 | 15 | a1i |  | 
						
							| 17 |  | eleq1 |  | 
						
							| 18 |  | breq2 |  | 
						
							| 19 | 16 17 18 | 3imtr3d |  | 
						
							| 20 | 19 | com12 |  |