| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rexcom4 |  | 
						
							| 2 |  | rexcom4 |  | 
						
							| 3 | 1 2 | orbi12i |  | 
						
							| 4 |  | 19.43 |  | 
						
							| 5 | 3 4 | bitr4i |  | 
						
							| 6 | 5 | rexbii |  | 
						
							| 7 |  | rexcom4 |  | 
						
							| 8 | 6 7 | bitri |  | 
						
							| 9 |  | simpl |  | 
						
							| 10 | 9 | exlimiv |  | 
						
							| 11 |  | elisset |  | 
						
							| 12 |  | ibar |  | 
						
							| 13 | 12 | bicomd |  | 
						
							| 14 | 13 | exbidv |  | 
						
							| 15 | 11 14 | syl5ibrcom |  | 
						
							| 16 | 10 15 | impbid2 |  | 
						
							| 17 | 16 | ralrexbid |  | 
						
							| 18 | 17 | adantr |  | 
						
							| 19 |  | simpl |  | 
						
							| 20 | 19 | exlimiv |  | 
						
							| 21 |  | elisset |  | 
						
							| 22 |  | ibar |  | 
						
							| 23 | 22 | bicomd |  | 
						
							| 24 | 23 | exbidv |  | 
						
							| 25 | 21 24 | syl5ibrcom |  | 
						
							| 26 | 20 25 | impbid2 |  | 
						
							| 27 | 26 | ralrexbid |  | 
						
							| 28 | 27 | adantl |  | 
						
							| 29 | 18 28 | orbi12d |  | 
						
							| 30 | 29 | ralrexbid |  | 
						
							| 31 | 8 30 | bitr3id |  | 
						
							| 32 |  | eqeq1 |  | 
						
							| 33 | 32 | anbi1d |  | 
						
							| 34 | 33 | rexbidv |  | 
						
							| 35 |  | eqeq1 |  | 
						
							| 36 | 35 | anbi1d |  | 
						
							| 37 | 36 | rexbidv |  | 
						
							| 38 | 34 37 | orbi12d |  | 
						
							| 39 | 38 | rexbidv |  | 
						
							| 40 | 39 | dmopabelb |  | 
						
							| 41 | 40 | elv |  | 
						
							| 42 |  | vex |  | 
						
							| 43 | 32 | rexbidv |  | 
						
							| 44 | 35 | rexbidv |  | 
						
							| 45 | 43 44 | orbi12d |  | 
						
							| 46 | 45 | rexbidv |  | 
						
							| 47 | 42 46 | elab |  | 
						
							| 48 | 31 41 47 | 3bitr4g |  | 
						
							| 49 | 48 | eqrdv |  |