| Step | Hyp | Ref | Expression | 
						
							| 1 |  | usgrexmpl.v |  | 
						
							| 2 |  | usgrexmpl.e |  | 
						
							| 3 |  | usgrexmpl.g |  | 
						
							| 4 |  | edgval |  | 
						
							| 5 | 1 2 3 | usgrexmpllem |  | 
						
							| 6 | 5 | simpri |  | 
						
							| 7 | 6 | rneqi |  | 
						
							| 8 |  | prex |  | 
						
							| 9 |  | prex |  | 
						
							| 10 | 8 9 | pm3.2i |  | 
						
							| 11 |  | prex |  | 
						
							| 12 |  | prex |  | 
						
							| 13 | 11 12 | pm3.2i |  | 
						
							| 14 | 10 13 | pm3.2i |  | 
						
							| 15 |  | usgrexmpldifpr |  | 
						
							| 16 | 14 15 | pm3.2i |  | 
						
							| 17 | 16 2 | pm3.2i |  | 
						
							| 18 |  | s4f1o |  | 
						
							| 19 | 18 | imp31 |  | 
						
							| 20 |  | dff1o5 |  | 
						
							| 21 | 20 | simprbi |  | 
						
							| 22 | 17 19 21 | mp2b |  | 
						
							| 23 | 4 7 22 | 3eqtri |  |