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Description: One-to-one onto mapping of the empty set. (Contributed by NM, 15-Apr-1998)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | f1o00 | |- ( F : (/) -1-1-onto-> A <-> ( F = (/) /\ A = (/) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | dff1o4 | |- ( F : (/) -1-1-onto-> A <-> ( F Fn (/) /\ `' F Fn A ) ) |
|
| 2 | fn0 | |- ( F Fn (/) <-> F = (/) ) |
|
| 3 | 2 | biimpi | |- ( F Fn (/) -> F = (/) ) |
| 4 | 3 | adantr | |- ( ( F Fn (/) /\ `' F Fn A ) -> F = (/) ) |
| 5 | cnveq | |- ( F = (/) -> `' F = `' (/) ) |
|
| 6 | cnv0 | |- `' (/) = (/) |
|
| 7 | 5 6 | eqtrdi | |- ( F = (/) -> `' F = (/) ) |
| 8 | 2 7 | sylbi | |- ( F Fn (/) -> `' F = (/) ) |
| 9 | 8 | fneq1d | |- ( F Fn (/) -> ( `' F Fn A <-> (/) Fn A ) ) |
| 10 | 9 | biimpa | |- ( ( F Fn (/) /\ `' F Fn A ) -> (/) Fn A ) |
| 11 | 10 | fndmd | |- ( ( F Fn (/) /\ `' F Fn A ) -> dom (/) = A ) |
| 12 | dm0 | |- dom (/) = (/) |
|
| 13 | 11 12 | eqtr3di | |- ( ( F Fn (/) /\ `' F Fn A ) -> A = (/) ) |
| 14 | 4 13 | jca | |- ( ( F Fn (/) /\ `' F Fn A ) -> ( F = (/) /\ A = (/) ) ) |
| 15 | 2 | biimpri | |- ( F = (/) -> F Fn (/) ) |
| 16 | 15 | adantr | |- ( ( F = (/) /\ A = (/) ) -> F Fn (/) ) |
| 17 | eqid | |- (/) = (/) |
|
| 18 | fn0 | |- ( (/) Fn (/) <-> (/) = (/) ) |
|
| 19 | 17 18 | mpbir | |- (/) Fn (/) |
| 20 | 7 | fneq1d | |- ( F = (/) -> ( `' F Fn A <-> (/) Fn A ) ) |
| 21 | fneq2 | |- ( A = (/) -> ( (/) Fn A <-> (/) Fn (/) ) ) |
|
| 22 | 20 21 | sylan9bb | |- ( ( F = (/) /\ A = (/) ) -> ( `' F Fn A <-> (/) Fn (/) ) ) |
| 23 | 19 22 | mpbiri | |- ( ( F = (/) /\ A = (/) ) -> `' F Fn A ) |
| 24 | 16 23 | jca | |- ( ( F = (/) /\ A = (/) ) -> ( F Fn (/) /\ `' F Fn A ) ) |
| 25 | 14 24 | impbii | |- ( ( F Fn (/) /\ `' F Fn A ) <-> ( F = (/) /\ A = (/) ) ) |
| 26 | 1 25 | bitri | |- ( F : (/) -1-1-onto-> A <-> ( F = (/) /\ A = (/) ) ) |