Description: If two classes are equinumerous, both classes are sets. (Contributed by AV, 21-Mar-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | encv | ⊢ ( 𝐴 ≈ 𝐵 → ( 𝐴 ∈ V ∧ 𝐵 ∈ V ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | relen | ⊢ Rel ≈ | |
| 2 | 1 | brrelex12i | ⊢ ( 𝐴 ≈ 𝐵 → ( 𝐴 ∈ V ∧ 𝐵 ∈ V ) ) |