| Step | Hyp | Ref | Expression | 
						
							| 1 |  | f1opw2.1 |  |-  ( ph -> F : A -1-1-onto-> B ) | 
						
							| 2 |  | f1opw2.2 |  |-  ( ph -> ( `' F " a ) e. _V ) | 
						
							| 3 |  | f1opw2.3 |  |-  ( ph -> ( F " b ) e. _V ) | 
						
							| 4 |  | eqid |  |-  ( b e. ~P A |-> ( F " b ) ) = ( b e. ~P A |-> ( F " b ) ) | 
						
							| 5 |  | imassrn |  |-  ( F " b ) C_ ran F | 
						
							| 6 |  | f1ofo |  |-  ( F : A -1-1-onto-> B -> F : A -onto-> B ) | 
						
							| 7 | 1 6 | syl |  |-  ( ph -> F : A -onto-> B ) | 
						
							| 8 |  | forn |  |-  ( F : A -onto-> B -> ran F = B ) | 
						
							| 9 | 7 8 | syl |  |-  ( ph -> ran F = B ) | 
						
							| 10 | 5 9 | sseqtrid |  |-  ( ph -> ( F " b ) C_ B ) | 
						
							| 11 | 3 10 | elpwd |  |-  ( ph -> ( F " b ) e. ~P B ) | 
						
							| 12 | 11 | adantr |  |-  ( ( ph /\ b e. ~P A ) -> ( F " b ) e. ~P B ) | 
						
							| 13 |  | imassrn |  |-  ( `' F " a ) C_ ran `' F | 
						
							| 14 |  | dfdm4 |  |-  dom F = ran `' F | 
						
							| 15 |  | f1odm |  |-  ( F : A -1-1-onto-> B -> dom F = A ) | 
						
							| 16 | 1 15 | syl |  |-  ( ph -> dom F = A ) | 
						
							| 17 | 14 16 | eqtr3id |  |-  ( ph -> ran `' F = A ) | 
						
							| 18 | 13 17 | sseqtrid |  |-  ( ph -> ( `' F " a ) C_ A ) | 
						
							| 19 | 2 18 | elpwd |  |-  ( ph -> ( `' F " a ) e. ~P A ) | 
						
							| 20 | 19 | adantr |  |-  ( ( ph /\ a e. ~P B ) -> ( `' F " a ) e. ~P A ) | 
						
							| 21 |  | elpwi |  |-  ( a e. ~P B -> a C_ B ) | 
						
							| 22 | 21 | adantl |  |-  ( ( b e. ~P A /\ a e. ~P B ) -> a C_ B ) | 
						
							| 23 |  | foimacnv |  |-  ( ( F : A -onto-> B /\ a C_ B ) -> ( F " ( `' F " a ) ) = a ) | 
						
							| 24 | 7 22 23 | syl2an |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> ( F " ( `' F " a ) ) = a ) | 
						
							| 25 | 24 | eqcomd |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> a = ( F " ( `' F " a ) ) ) | 
						
							| 26 |  | imaeq2 |  |-  ( b = ( `' F " a ) -> ( F " b ) = ( F " ( `' F " a ) ) ) | 
						
							| 27 | 26 | eqeq2d |  |-  ( b = ( `' F " a ) -> ( a = ( F " b ) <-> a = ( F " ( `' F " a ) ) ) ) | 
						
							| 28 | 25 27 | syl5ibrcom |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> ( b = ( `' F " a ) -> a = ( F " b ) ) ) | 
						
							| 29 |  | f1of1 |  |-  ( F : A -1-1-onto-> B -> F : A -1-1-> B ) | 
						
							| 30 | 1 29 | syl |  |-  ( ph -> F : A -1-1-> B ) | 
						
							| 31 |  | elpwi |  |-  ( b e. ~P A -> b C_ A ) | 
						
							| 32 | 31 | adantr |  |-  ( ( b e. ~P A /\ a e. ~P B ) -> b C_ A ) | 
						
							| 33 |  | f1imacnv |  |-  ( ( F : A -1-1-> B /\ b C_ A ) -> ( `' F " ( F " b ) ) = b ) | 
						
							| 34 | 30 32 33 | syl2an |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> ( `' F " ( F " b ) ) = b ) | 
						
							| 35 | 34 | eqcomd |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> b = ( `' F " ( F " b ) ) ) | 
						
							| 36 |  | imaeq2 |  |-  ( a = ( F " b ) -> ( `' F " a ) = ( `' F " ( F " b ) ) ) | 
						
							| 37 | 36 | eqeq2d |  |-  ( a = ( F " b ) -> ( b = ( `' F " a ) <-> b = ( `' F " ( F " b ) ) ) ) | 
						
							| 38 | 35 37 | syl5ibrcom |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> ( a = ( F " b ) -> b = ( `' F " a ) ) ) | 
						
							| 39 | 28 38 | impbid |  |-  ( ( ph /\ ( b e. ~P A /\ a e. ~P B ) ) -> ( b = ( `' F " a ) <-> a = ( F " b ) ) ) | 
						
							| 40 | 4 12 20 39 | f1o2d |  |-  ( ph -> ( b e. ~P A |-> ( F " b ) ) : ~P A -1-1-onto-> ~P B ) |