| Step | Hyp | Ref | Expression | 
						
							| 1 |  | btwnlng1.p |  | 
						
							| 2 |  | btwnlng1.i |  | 
						
							| 3 |  | btwnlng1.l |  | 
						
							| 4 |  | btwnlng1.g |  | 
						
							| 5 |  | btwnlng1.x |  | 
						
							| 6 |  | btwnlng1.y |  | 
						
							| 7 |  | btwnlng1.z |  | 
						
							| 8 |  | btwnlng1.d |  | 
						
							| 9 |  | lnrot2.1 |  | 
						
							| 10 |  | lnrot2.2 |  | 
						
							| 11 |  | eqid |  | 
						
							| 12 | 1 11 2 4 6 5 7 | tgbtwncomb |  | 
						
							| 13 |  | biidd |  | 
						
							| 14 | 1 11 2 4 6 7 5 | tgbtwncomb |  | 
						
							| 15 | 12 13 14 | 3orbi123d |  | 
						
							| 16 |  | 3orrot |  | 
						
							| 17 | 15 16 | bitr4di |  | 
						
							| 18 | 1 3 2 4 6 7 10 5 | tgellng |  | 
						
							| 19 | 1 3 2 4 5 6 8 7 | tgellng |  | 
						
							| 20 | 17 18 19 | 3bitr4d |  | 
						
							| 21 | 9 20 | mpbid |  |