| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdsymlem1.1 |  | 
						
							| 2 |  | mdsymlem1.2 |  | 
						
							| 3 |  | mdsymlem1.3 |  | 
						
							| 4 | 1 2 | chjcomi |  | 
						
							| 5 | 4 | sseq2i |  | 
						
							| 6 |  | atelch |  | 
						
							| 7 |  | atelch |  | 
						
							| 8 |  | chjcom |  | 
						
							| 9 | 6 7 8 | syl2an |  | 
						
							| 10 | 9 | sseq2d |  | 
						
							| 11 |  | ancom |  | 
						
							| 12 | 11 | a1i |  | 
						
							| 13 | 10 12 | anbi12d |  | 
						
							| 14 | 13 | 2rexbiia |  | 
						
							| 15 |  | rexcom |  | 
						
							| 16 | 14 15 | bitri |  | 
						
							| 17 | 5 16 | imbi12i |  | 
						
							| 18 | 17 | ralbii |  | 
						
							| 19 | 18 | a1i |  | 
						
							| 20 | 1 2 3 | mdsymlem7 |  | 
						
							| 21 |  | eqid |  | 
						
							| 22 | 2 1 21 | mdsymlem7 |  | 
						
							| 23 | 22 | ancoms |  | 
						
							| 24 | 19 20 23 | 3bitr4d |  |