| Step | Hyp | Ref | Expression | 
						
							| 1 |  | iblcn.1 |  | 
						
							| 2 | 1 | ismbfcn2 |  | 
						
							| 3 | 2 | anbi1d |  | 
						
							| 4 |  | 3anass |  | 
						
							| 5 |  | an4 |  | 
						
							| 6 | 3 4 5 | 3bitr4g |  | 
						
							| 7 |  | eqid |  | 
						
							| 8 |  | eqid |  | 
						
							| 9 |  | eqid |  | 
						
							| 10 |  | eqid |  | 
						
							| 11 | 7 8 9 10 1 | iblcnlem1 |  | 
						
							| 12 | 1 | recld |  | 
						
							| 13 | 12 | iblrelem |  | 
						
							| 14 |  | 3anass |  | 
						
							| 15 | 13 14 | bitrdi |  | 
						
							| 16 | 1 | imcld |  | 
						
							| 17 | 16 | iblrelem |  | 
						
							| 18 |  | 3anass |  | 
						
							| 19 | 17 18 | bitrdi |  | 
						
							| 20 | 15 19 | anbi12d |  | 
						
							| 21 | 6 11 20 | 3bitr4d |  |