| Step | Hyp | Ref | Expression | 
						
							| 1 |  | psubclset.a |  | 
						
							| 2 |  | psubclset.p |  | 
						
							| 3 |  | psubclset.c |  | 
						
							| 4 |  | elex |  | 
						
							| 5 |  | fveq2 |  | 
						
							| 6 | 5 1 | eqtr4di |  | 
						
							| 7 | 6 | sseq2d |  | 
						
							| 8 |  | fveq2 |  | 
						
							| 9 | 8 2 | eqtr4di |  | 
						
							| 10 | 9 | fveq1d |  | 
						
							| 11 | 9 10 | fveq12d |  | 
						
							| 12 | 11 | eqeq1d |  | 
						
							| 13 | 7 12 | anbi12d |  | 
						
							| 14 | 13 | abbidv |  | 
						
							| 15 |  | df-psubclN |  | 
						
							| 16 | 1 | fvexi |  | 
						
							| 17 | 16 | pwex |  | 
						
							| 18 |  | velpw |  | 
						
							| 19 | 18 | anbi1i |  | 
						
							| 20 | 19 | abbii |  | 
						
							| 21 |  | ssab2 |  | 
						
							| 22 | 20 21 | eqsstrri |  | 
						
							| 23 | 17 22 | ssexi |  | 
						
							| 24 | 14 15 23 | fvmpt |  | 
						
							| 25 | 3 24 | eqtrid |  | 
						
							| 26 | 4 25 | syl |  |