| Step | Hyp | Ref | Expression | 
						
							| 1 |  | preq12bg |  | 
						
							| 2 |  | orddi |  | 
						
							| 3 |  | simpll |  | 
						
							| 4 |  | pm1.4 |  | 
						
							| 5 | 4 | ad2antll |  | 
						
							| 6 | 3 5 | jca |  | 
						
							| 7 | 2 6 | sylbi |  | 
						
							| 8 | 1 7 | biimtrdi |  | 
						
							| 9 |  | ianor |  | 
						
							| 10 |  | nne |  | 
						
							| 11 |  | nne |  | 
						
							| 12 | 10 11 | orbi12i |  | 
						
							| 13 | 9 12 | bitr2i |  | 
						
							| 14 |  | ianor |  | 
						
							| 15 |  | nne |  | 
						
							| 16 |  | nne |  | 
						
							| 17 | 15 16 | orbi12i |  | 
						
							| 18 | 14 17 | bitr2i |  | 
						
							| 19 | 13 18 | anbi12i |  | 
						
							| 20 | 8 19 | imbitrdi |  | 
						
							| 21 |  | pm4.56 |  | 
						
							| 22 | 20 21 | imbitrdi |  | 
						
							| 23 | 22 | necon2ad |  |