| 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 |  | rexcom4 |  | 
						
							| 10 | 9 | rexbii |  | 
						
							| 11 |  | rexcom4 |  | 
						
							| 12 | 10 11 | bitri |  | 
						
							| 13 | 8 12 | orbi12i |  | 
						
							| 14 |  | 19.43 |  | 
						
							| 15 | 13 14 | bitr4i |  | 
						
							| 16 |  | difssd |  | 
						
							| 17 |  | ssralv |  | 
						
							| 18 | 16 17 | syl |  | 
						
							| 19 | 18 | impcom |  | 
						
							| 20 |  | simpl |  | 
						
							| 21 | 20 | exlimiv |  | 
						
							| 22 |  | elisset |  | 
						
							| 23 |  | ibar |  | 
						
							| 24 | 23 | bicomd |  | 
						
							| 25 | 24 | exbidv |  | 
						
							| 26 | 22 25 | syl5ibrcom |  | 
						
							| 27 | 21 26 | impbid2 |  | 
						
							| 28 | 27 | ralrexbid |  | 
						
							| 29 | 28 | adantr |  | 
						
							| 30 |  | simpl |  | 
						
							| 31 | 30 | exlimiv |  | 
						
							| 32 |  | elisset |  | 
						
							| 33 |  | ibar |  | 
						
							| 34 | 33 | bicomd |  | 
						
							| 35 | 34 | exbidv |  | 
						
							| 36 | 32 35 | syl5ibrcom |  | 
						
							| 37 | 31 36 | impbid2 |  | 
						
							| 38 | 37 | ralrexbid |  | 
						
							| 39 | 38 | adantl |  | 
						
							| 40 | 29 39 | orbi12d |  | 
						
							| 41 | 40 | ralrexbid |  | 
						
							| 42 | 19 41 | syl |  | 
						
							| 43 |  | ssralv |  | 
						
							| 44 |  | ssralv |  | 
						
							| 45 | 16 44 | syl |  | 
						
							| 46 | 45 | adantrd |  | 
						
							| 47 | 46 | ralimdv |  | 
						
							| 48 | 43 47 | syld |  | 
						
							| 49 | 48 | impcom |  | 
						
							| 50 | 27 | ralrexbid |  | 
						
							| 51 | 50 | ralrexbid |  | 
						
							| 52 | 49 51 | syl |  | 
						
							| 53 | 42 52 | orbi12d |  | 
						
							| 54 | 15 53 | bitr3id |  | 
						
							| 55 |  | eqeq1 |  | 
						
							| 56 | 55 | anbi1d |  | 
						
							| 57 | 56 | rexbidv |  | 
						
							| 58 |  | eqeq1 |  | 
						
							| 59 | 58 | anbi1d |  | 
						
							| 60 | 59 | rexbidv |  | 
						
							| 61 | 57 60 | orbi12d |  | 
						
							| 62 | 61 | rexbidv |  | 
						
							| 63 | 56 | 2rexbidv |  | 
						
							| 64 | 62 63 | orbi12d |  | 
						
							| 65 | 64 | dmopabelb |  | 
						
							| 66 | 65 | elv |  | 
						
							| 67 |  | vex |  | 
						
							| 68 | 55 | rexbidv |  | 
						
							| 69 | 58 | rexbidv |  | 
						
							| 70 | 68 69 | orbi12d |  | 
						
							| 71 | 70 | rexbidv |  | 
						
							| 72 | 55 | 2rexbidv |  | 
						
							| 73 | 71 72 | orbi12d |  | 
						
							| 74 | 67 73 | elab |  | 
						
							| 75 | 54 66 74 | 3bitr4g |  | 
						
							| 76 | 75 | eqrdv |  |