Description: Algebraicity of a point closure condition. (Contributed by Stefan O'Rear, 3-Apr-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | acsfn0 | ⊢ ( ( 𝑋 ∈ 𝑉 ∧ 𝐾 ∈ 𝑋 ) → { 𝑎 ∈ 𝒫 𝑋 ∣ 𝐾 ∈ 𝑎 } ∈ ( ACS ‘ 𝑋 ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ss | ⊢ ∅ ⊆ 𝑎 | |
2 | 1 | a1bi | ⊢ ( 𝐾 ∈ 𝑎 ↔ ( ∅ ⊆ 𝑎 → 𝐾 ∈ 𝑎 ) ) |
3 | 2 | rabbii | ⊢ { 𝑎 ∈ 𝒫 𝑋 ∣ 𝐾 ∈ 𝑎 } = { 𝑎 ∈ 𝒫 𝑋 ∣ ( ∅ ⊆ 𝑎 → 𝐾 ∈ 𝑎 ) } |
4 | 0ss | ⊢ ∅ ⊆ 𝑋 | |
5 | 0fin | ⊢ ∅ ∈ Fin | |
6 | acsfn | ⊢ ( ( ( 𝑋 ∈ 𝑉 ∧ 𝐾 ∈ 𝑋 ) ∧ ( ∅ ⊆ 𝑋 ∧ ∅ ∈ Fin ) ) → { 𝑎 ∈ 𝒫 𝑋 ∣ ( ∅ ⊆ 𝑎 → 𝐾 ∈ 𝑎 ) } ∈ ( ACS ‘ 𝑋 ) ) | |
7 | 4 5 6 | mpanr12 | ⊢ ( ( 𝑋 ∈ 𝑉 ∧ 𝐾 ∈ 𝑋 ) → { 𝑎 ∈ 𝒫 𝑋 ∣ ( ∅ ⊆ 𝑎 → 𝐾 ∈ 𝑎 ) } ∈ ( ACS ‘ 𝑋 ) ) |
8 | 3 7 | eqeltrid | ⊢ ( ( 𝑋 ∈ 𝑉 ∧ 𝐾 ∈ 𝑋 ) → { 𝑎 ∈ 𝒫 𝑋 ∣ 𝐾 ∈ 𝑎 } ∈ ( ACS ‘ 𝑋 ) ) |