Description: Obsolete version of tz6.12-1 as of 23-Dec-2024. (Contributed by NM, 30-Apr-2004) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | tz6.12-1OLD | |- ( ( A F y /\ E! y A F y ) -> ( F ` A ) = y ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-fv | |- ( F ` A ) = ( iota y A F y ) |
|
| 2 | iota1 | |- ( E! y A F y -> ( A F y <-> ( iota y A F y ) = y ) ) |
|
| 3 | 2 | biimpac | |- ( ( A F y /\ E! y A F y ) -> ( iota y A F y ) = y ) |
| 4 | 1 3 | eqtrid | |- ( ( A F y /\ E! y A F y ) -> ( F ` A ) = y ) |