| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nvinvfval.2 |  | 
						
							| 2 |  | nvinvfval.4 |  | 
						
							| 3 |  | nvinvfval.3 |  | 
						
							| 4 |  | eqid |  | 
						
							| 5 | 4 2 | nvsf |  | 
						
							| 6 |  | neg1cn |  | 
						
							| 7 | 3 | curry1f |  | 
						
							| 8 | 5 6 7 | sylancl |  | 
						
							| 9 | 8 | ffnd |  | 
						
							| 10 | 1 | nvgrp |  | 
						
							| 11 | 4 1 | bafval |  | 
						
							| 12 |  | eqid |  | 
						
							| 13 | 11 12 | grpoinvf |  | 
						
							| 14 |  | f1ofn |  | 
						
							| 15 | 10 13 14 | 3syl |  | 
						
							| 16 | 5 | ffnd |  | 
						
							| 17 | 16 | adantr |  | 
						
							| 18 | 3 | curry1val |  | 
						
							| 19 | 17 6 18 | sylancl |  | 
						
							| 20 | 4 1 2 12 | nvinv |  | 
						
							| 21 | 19 20 | eqtrd |  | 
						
							| 22 | 9 15 21 | eqfnfvd |  |