| Step | Hyp | Ref | Expression | 
						
							| 1 |  | inocv.o |  | 
						
							| 2 |  | unss |  | 
						
							| 3 | 2 | bicomi |  | 
						
							| 4 |  | ralunb |  | 
						
							| 5 | 3 4 | anbi12i |  | 
						
							| 6 |  | an4 |  | 
						
							| 7 | 5 6 | bitri |  | 
						
							| 8 | 7 | anbi2i |  | 
						
							| 9 |  | eqid |  | 
						
							| 10 |  | eqid |  | 
						
							| 11 |  | eqid |  | 
						
							| 12 |  | eqid |  | 
						
							| 13 | 9 10 11 12 1 | elocv |  | 
						
							| 14 |  | 3anan12 |  | 
						
							| 15 | 13 14 | bitri |  | 
						
							| 16 | 9 10 11 12 1 | elocv |  | 
						
							| 17 |  | 3anan12 |  | 
						
							| 18 | 16 17 | bitri |  | 
						
							| 19 | 9 10 11 12 1 | elocv |  | 
						
							| 20 |  | 3anan12 |  | 
						
							| 21 | 19 20 | bitri |  | 
						
							| 22 | 18 21 | anbi12i |  | 
						
							| 23 |  | elin |  | 
						
							| 24 |  | anandi |  | 
						
							| 25 | 22 23 24 | 3bitr4i |  | 
						
							| 26 | 8 15 25 | 3bitr4i |  | 
						
							| 27 | 26 | eqriv |  |