| Step | Hyp | Ref | Expression | 
						
							| 1 |  | iscring2.1 |  | 
						
							| 2 |  | iscring2.2 |  | 
						
							| 3 |  | iscring2.3 |  | 
						
							| 4 |  | iscrngo |  | 
						
							| 5 |  | relrngo |  | 
						
							| 6 |  | 1st2nd |  | 
						
							| 7 | 5 6 | mpan |  | 
						
							| 8 |  | eleq1 |  | 
						
							| 9 | 1 | rneqi |  | 
						
							| 10 | 3 9 | eqtri |  | 
						
							| 11 | 10 | raleqi |  | 
						
							| 12 | 2 | oveqi |  | 
						
							| 13 | 2 | oveqi |  | 
						
							| 14 | 12 13 | eqeq12i |  | 
						
							| 15 | 10 14 | raleqbii |  | 
						
							| 16 | 15 | ralbii |  | 
						
							| 17 |  | fvex |  | 
						
							| 18 |  | fvex |  | 
						
							| 19 |  | iscom2 |  | 
						
							| 20 | 17 18 19 | mp2an |  | 
						
							| 21 | 11 16 20 | 3bitr4ri |  | 
						
							| 22 | 8 21 | bitrdi |  | 
						
							| 23 | 7 22 | syl |  | 
						
							| 24 | 23 | pm5.32i |  | 
						
							| 25 | 4 24 | bitri |  |