| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdsym.1 |  | 
						
							| 2 |  | mdsym.2 |  | 
						
							| 3 | 2 | choccli |  | 
						
							| 4 | 1 | choccli |  | 
						
							| 5 |  | eqid |  | 
						
							| 6 | 3 4 5 | mdsymlem8 |  | 
						
							| 7 |  | mddmd |  | 
						
							| 8 | 1 2 7 | mp2an |  | 
						
							| 9 |  | mddmd |  | 
						
							| 10 | 2 1 9 | mp2an |  | 
						
							| 11 | 6 8 10 | 3bitr4g |  | 
						
							| 12 | 1 | chssii |  | 
						
							| 13 |  | fveq2 |  | 
						
							| 14 | 2 | pjococi |  | 
						
							| 15 |  | choc0 |  | 
						
							| 16 | 13 14 15 | 3eqtr3g |  | 
						
							| 17 | 12 16 | sseqtrrid |  | 
						
							| 18 |  | ssmd1 |  | 
						
							| 19 | 1 2 18 | mp3an12 |  | 
						
							| 20 |  | ssmd2 |  | 
						
							| 21 | 1 2 20 | mp3an12 |  | 
						
							| 22 | 19 21 | jca |  | 
						
							| 23 |  | pm5.1 |  | 
						
							| 24 | 17 22 23 | 3syl |  | 
						
							| 25 | 2 | chssii |  | 
						
							| 26 |  | fveq2 |  | 
						
							| 27 | 1 | pjococi |  | 
						
							| 28 | 26 27 15 | 3eqtr3g |  | 
						
							| 29 | 25 28 | sseqtrrid |  | 
						
							| 30 |  | ssmd2 |  | 
						
							| 31 | 2 1 30 | mp3an12 |  | 
						
							| 32 |  | ssmd1 |  | 
						
							| 33 | 2 1 32 | mp3an12 |  | 
						
							| 34 | 31 33 | jca |  | 
						
							| 35 | 29 34 23 | 3syl |  | 
						
							| 36 | 11 24 35 | pm2.61iine |  |