| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rngcsect.c |  | 
						
							| 2 |  | rngcsect.b |  | 
						
							| 3 |  | rngcsect.u |  | 
						
							| 4 |  | rngcsect.x |  | 
						
							| 5 |  | rngcsect.y |  | 
						
							| 6 |  | rngciso.n |  | 
						
							| 7 |  | eqid |  | 
						
							| 8 | 1 | rngccat |  | 
						
							| 9 | 3 8 | syl |  | 
						
							| 10 | 2 7 9 4 5 6 | isoval |  | 
						
							| 11 | 10 | eleq2d |  | 
						
							| 12 | 2 7 9 4 5 | invfun |  | 
						
							| 13 |  | funfvbrb |  | 
						
							| 14 | 12 13 | syl |  | 
						
							| 15 | 1 2 3 4 5 7 | rngcinv |  | 
						
							| 16 |  | simpl |  | 
						
							| 17 | 15 16 | biimtrdi |  | 
						
							| 18 | 14 17 | sylbid |  | 
						
							| 19 |  | eqid |  | 
						
							| 20 | 1 2 3 4 5 7 | rngcinv |  | 
						
							| 21 |  | funrel |  | 
						
							| 22 | 12 21 | syl |  | 
						
							| 23 |  | releldm |  | 
						
							| 24 | 23 | ex |  | 
						
							| 25 | 22 24 | syl |  | 
						
							| 26 | 20 25 | sylbird |  | 
						
							| 27 | 19 26 | mpan2i |  | 
						
							| 28 | 18 27 | impbid |  | 
						
							| 29 | 11 28 | bitrd |  |