Description: If a class is a member of another class, then it is a set. Inference associated with elex . (Contributed by NM, 11-Jun-1994)
Ref | Expression | ||
---|---|---|---|
Hypothesis | elexi.1 | ⊢ 𝐴 ∈ 𝐵 | |
Assertion | elexi | ⊢ 𝐴 ∈ V |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elexi.1 | ⊢ 𝐴 ∈ 𝐵 | |
2 | elex | ⊢ ( 𝐴 ∈ 𝐵 → 𝐴 ∈ V ) | |
3 | 1 2 | ax-mp | ⊢ 𝐴 ∈ V |