| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdslle1.1 |  | 
						
							| 2 |  | mdslle1.2 |  | 
						
							| 3 |  | mdslle1.3 |  | 
						
							| 4 |  | mdslle1.4 |  | 
						
							| 5 | 3 4 1 | chlej1i |  | 
						
							| 6 |  | ssrin |  | 
						
							| 7 |  | id |  | 
						
							| 8 |  | ssin |  | 
						
							| 9 | 8 | bicomi |  | 
						
							| 10 | 9 | simplbi |  | 
						
							| 11 | 3 4 2 | chlubi |  | 
						
							| 12 | 11 | bicomi |  | 
						
							| 13 | 12 | simplbi |  | 
						
							| 14 | 1 2 3 | 3pm3.2i |  | 
						
							| 15 |  | mdsl3 |  | 
						
							| 16 | 14 15 | mpan |  | 
						
							| 17 | 7 10 13 16 | syl3an |  | 
						
							| 18 | 9 | simprbi |  | 
						
							| 19 | 12 | simprbi |  | 
						
							| 20 | 1 2 4 | 3pm3.2i |  | 
						
							| 21 |  | mdsl3 |  | 
						
							| 22 | 20 21 | mpan |  | 
						
							| 23 | 7 18 19 22 | syl3an |  | 
						
							| 24 | 17 23 | sseq12d |  | 
						
							| 25 | 6 24 | imbitrid |  | 
						
							| 26 | 5 25 | impbid2 |  |