| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 4at.l |  | 
						
							| 2 |  | 4at.j |  | 
						
							| 3 |  | 4at.a |  | 
						
							| 4 |  | simpl1 |  | 
						
							| 5 |  | simpl2 |  | 
						
							| 6 |  | simpl3 |  | 
						
							| 7 |  | simprl |  | 
						
							| 8 |  | simprr |  | 
						
							| 9 | 2 3 | hlatj4 |  | 
						
							| 10 | 4 5 6 7 8 9 | syl122anc |  | 
						
							| 11 | 4 | hllatd |  | 
						
							| 12 |  | eqid |  | 
						
							| 13 | 12 2 3 | hlatjcl |  | 
						
							| 14 | 4 5 7 13 | syl3anc |  | 
						
							| 15 | 12 3 | atbase |  | 
						
							| 16 | 6 15 | syl |  | 
						
							| 17 | 12 3 | atbase |  | 
						
							| 18 | 17 | ad2antll |  | 
						
							| 19 | 12 2 | latj12 |  | 
						
							| 20 | 11 14 16 18 19 | syl13anc |  | 
						
							| 21 | 10 20 | eqtrd |  |