| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dssmapfvd.o |  |-  O = ( b e. _V |-> ( f e. ( ~P b ^m ~P b ) |-> ( s e. ~P b |-> ( b \ ( f ` ( b \ s ) ) ) ) ) ) | 
						
							| 2 |  | dssmapfvd.d |  |-  D = ( O ` B ) | 
						
							| 3 |  | dssmapfvd.b |  |-  ( ph -> B e. V ) | 
						
							| 4 |  | dssmapfv2d.f |  |-  ( ph -> F e. ( ~P B ^m ~P B ) ) | 
						
							| 5 |  | dssmapfv2d.g |  |-  G = ( D ` F ) | 
						
							| 6 | 1 2 3 | dssmapfvd |  |-  ( ph -> D = ( f e. ( ~P B ^m ~P B ) |-> ( s e. ~P B |-> ( B \ ( f ` ( B \ s ) ) ) ) ) ) | 
						
							| 7 |  | fveq1 |  |-  ( f = F -> ( f ` ( B \ s ) ) = ( F ` ( B \ s ) ) ) | 
						
							| 8 | 7 | difeq2d |  |-  ( f = F -> ( B \ ( f ` ( B \ s ) ) ) = ( B \ ( F ` ( B \ s ) ) ) ) | 
						
							| 9 | 8 | mpteq2dv |  |-  ( f = F -> ( s e. ~P B |-> ( B \ ( f ` ( B \ s ) ) ) ) = ( s e. ~P B |-> ( B \ ( F ` ( B \ s ) ) ) ) ) | 
						
							| 10 | 9 | adantl |  |-  ( ( ph /\ f = F ) -> ( s e. ~P B |-> ( B \ ( f ` ( B \ s ) ) ) ) = ( s e. ~P B |-> ( B \ ( F ` ( B \ s ) ) ) ) ) | 
						
							| 11 |  | pwexg |  |-  ( B e. V -> ~P B e. _V ) | 
						
							| 12 |  | mptexg |  |-  ( ~P B e. _V -> ( s e. ~P B |-> ( B \ ( F ` ( B \ s ) ) ) ) e. _V ) | 
						
							| 13 | 3 11 12 | 3syl |  |-  ( ph -> ( s e. ~P B |-> ( B \ ( F ` ( B \ s ) ) ) ) e. _V ) | 
						
							| 14 | 6 10 4 13 | fvmptd |  |-  ( ph -> ( D ` F ) = ( s e. ~P B |-> ( B \ ( F ` ( B \ s ) ) ) ) ) | 
						
							| 15 | 5 14 | eqtrid |  |-  ( ph -> G = ( s e. ~P B |-> ( B \ ( F ` ( B \ s ) ) ) ) ) |