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Description: A closed subset of the codomain of a continuous function has a closed preimage. (Contributed by NM, 15-Mar-2007) (Revised by Mario Carneiro, 21-Aug-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | cnclima | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ◡ 𝐹 “ 𝐴 ) ∈ ( Clsd ‘ 𝐽 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eqid | ⊢ ∪ 𝐽 = ∪ 𝐽 | |
| 2 | eqid | ⊢ ∪ 𝐾 = ∪ 𝐾 | |
| 3 | 1 2 | cnf | ⊢ ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) → 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 ) |
| 4 | 3 | adantr | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 ) |
| 5 | ffun | ⊢ ( 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 → Fun 𝐹 ) | |
| 6 | funcnvcnv | ⊢ ( Fun 𝐹 → Fun ◡ ◡ 𝐹 ) | |
| 7 | imadif | ⊢ ( Fun ◡ ◡ 𝐹 → ( ◡ 𝐹 “ ( ∪ 𝐾 ∖ 𝐴 ) ) = ( ( ◡ 𝐹 “ ∪ 𝐾 ) ∖ ( ◡ 𝐹 “ 𝐴 ) ) ) | |
| 8 | 5 6 7 | 3syl | ⊢ ( 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 → ( ◡ 𝐹 “ ( ∪ 𝐾 ∖ 𝐴 ) ) = ( ( ◡ 𝐹 “ ∪ 𝐾 ) ∖ ( ◡ 𝐹 “ 𝐴 ) ) ) |
| 9 | fimacnv | ⊢ ( 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 → ( ◡ 𝐹 “ ∪ 𝐾 ) = ∪ 𝐽 ) | |
| 10 | 9 | difeq1d | ⊢ ( 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 → ( ( ◡ 𝐹 “ ∪ 𝐾 ) ∖ ( ◡ 𝐹 “ 𝐴 ) ) = ( ∪ 𝐽 ∖ ( ◡ 𝐹 “ 𝐴 ) ) ) |
| 11 | 8 10 | eqtr2d | ⊢ ( 𝐹 : ∪ 𝐽 ⟶ ∪ 𝐾 → ( ∪ 𝐽 ∖ ( ◡ 𝐹 “ 𝐴 ) ) = ( ◡ 𝐹 “ ( ∪ 𝐾 ∖ 𝐴 ) ) ) |
| 12 | 4 11 | syl | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ∪ 𝐽 ∖ ( ◡ 𝐹 “ 𝐴 ) ) = ( ◡ 𝐹 “ ( ∪ 𝐾 ∖ 𝐴 ) ) ) |
| 13 | 2 | cldopn | ⊢ ( 𝐴 ∈ ( Clsd ‘ 𝐾 ) → ( ∪ 𝐾 ∖ 𝐴 ) ∈ 𝐾 ) |
| 14 | cnima | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ ( ∪ 𝐾 ∖ 𝐴 ) ∈ 𝐾 ) → ( ◡ 𝐹 “ ( ∪ 𝐾 ∖ 𝐴 ) ) ∈ 𝐽 ) | |
| 15 | 13 14 | sylan2 | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ◡ 𝐹 “ ( ∪ 𝐾 ∖ 𝐴 ) ) ∈ 𝐽 ) |
| 16 | 12 15 | eqeltrd | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ∪ 𝐽 ∖ ( ◡ 𝐹 “ 𝐴 ) ) ∈ 𝐽 ) |
| 17 | cntop1 | ⊢ ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) → 𝐽 ∈ Top ) | |
| 18 | cnvimass | ⊢ ( ◡ 𝐹 “ 𝐴 ) ⊆ dom 𝐹 | |
| 19 | 18 4 | fssdm | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ◡ 𝐹 “ 𝐴 ) ⊆ ∪ 𝐽 ) |
| 20 | 1 | iscld2 | ⊢ ( ( 𝐽 ∈ Top ∧ ( ◡ 𝐹 “ 𝐴 ) ⊆ ∪ 𝐽 ) → ( ( ◡ 𝐹 “ 𝐴 ) ∈ ( Clsd ‘ 𝐽 ) ↔ ( ∪ 𝐽 ∖ ( ◡ 𝐹 “ 𝐴 ) ) ∈ 𝐽 ) ) |
| 21 | 17 19 20 | syl2an2r | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ( ◡ 𝐹 “ 𝐴 ) ∈ ( Clsd ‘ 𝐽 ) ↔ ( ∪ 𝐽 ∖ ( ◡ 𝐹 “ 𝐴 ) ) ∈ 𝐽 ) ) |
| 22 | 16 21 | mpbird | ⊢ ( ( 𝐹 ∈ ( 𝐽 Cn 𝐾 ) ∧ 𝐴 ∈ ( Clsd ‘ 𝐾 ) ) → ( ◡ 𝐹 “ 𝐴 ) ∈ ( Clsd ‘ 𝐽 ) ) |