Description: Sethood of certain classes. (Contributed by BJ, 2-Apr-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-clexab | ⊢ ( 𝐴 ∈ 𝑉 → { 𝑥 ∣ { 𝑥 } ∈ ( 𝐴 “ 𝐵 ) } ∈ V ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | imaexg | ⊢ ( 𝐴 ∈ 𝑉 → ( 𝐴 “ 𝐵 ) ∈ V ) | |
| 2 | bj-snsetex | ⊢ ( ( 𝐴 “ 𝐵 ) ∈ V → { 𝑥 ∣ { 𝑥 } ∈ ( 𝐴 “ 𝐵 ) } ∈ V ) | |
| 3 | 1 2 | syl | ⊢ ( 𝐴 ∈ 𝑉 → { 𝑥 ∣ { 𝑥 } ∈ ( 𝐴 “ 𝐵 ) } ∈ V ) |