| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ausgr.1 |  | 
						
							| 2 |  | fvex |  | 
						
							| 3 |  | fvex |  | 
						
							| 4 | 1 | isausgr |  | 
						
							| 5 | 2 3 4 | mp2an |  | 
						
							| 6 |  | edgval |  | 
						
							| 7 | 6 | a1i |  | 
						
							| 8 | 7 | sseq1d |  | 
						
							| 9 |  | funfn |  | 
						
							| 10 | 9 | biimpi |  | 
						
							| 11 | 10 | 3ad2ant3 |  | 
						
							| 12 |  | simp2 |  | 
						
							| 13 |  | df-f |  | 
						
							| 14 | 11 12 13 | sylanbrc |  | 
						
							| 15 | 14 | 3exp |  | 
						
							| 16 | 8 15 | sylbid |  | 
						
							| 17 | 5 16 | biimtrid |  | 
						
							| 18 | 17 | 3imp |  | 
						
							| 19 |  | eqid |  | 
						
							| 20 |  | eqid |  | 
						
							| 21 | 19 20 | isumgrs |  | 
						
							| 22 | 21 | 3ad2ant1 |  | 
						
							| 23 | 18 22 | mpbird |  |