| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 3anass |  | 
						
							| 2 |  | 3anan12 |  | 
						
							| 3 |  | 3anrev |  | 
						
							| 4 |  | 3anass |  | 
						
							| 5 | 3 4 | bitri |  | 
						
							| 6 | 1 2 5 | 3anbi123i |  | 
						
							| 7 |  | 3an6 |  | 
						
							| 8 |  | anass |  | 
						
							| 9 | 8 | anbi2i |  | 
						
							| 10 |  | an42 |  | 
						
							| 11 | 9 10 | bitri |  | 
						
							| 12 |  | anass |  | 
						
							| 13 |  | anass |  | 
						
							| 14 | 11 12 13 | 3bitr4i |  | 
						
							| 15 | 14 | anbi1i |  | 
						
							| 16 |  | anass |  | 
						
							| 17 |  | anass |  | 
						
							| 18 | 15 16 17 | 3bitr3i |  | 
						
							| 19 |  | df-3an |  | 
						
							| 20 |  | df-3an |  | 
						
							| 21 | 18 19 20 | 3bitr4i |  | 
						
							| 22 | 21 | anbi2i |  | 
						
							| 23 | 6 7 22 | 3bitri |  |