Description: If an ordered pair has an element, then its arguments are sets. (Contributed by Mario Carneiro, 26-Apr-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | oprcl | ⊢ ( 𝐶 ∈ 〈 𝐴 , 𝐵 〉 → ( 𝐴 ∈ V ∧ 𝐵 ∈ V ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | n0i | ⊢ ( 𝐶 ∈ 〈 𝐴 , 𝐵 〉 → ¬ 〈 𝐴 , 𝐵 〉 = ∅ ) | |
| 2 | opprc | ⊢ ( ¬ ( 𝐴 ∈ V ∧ 𝐵 ∈ V ) → 〈 𝐴 , 𝐵 〉 = ∅ ) | |
| 3 | 1 2 | nsyl2 | ⊢ ( 𝐶 ∈ 〈 𝐴 , 𝐵 〉 → ( 𝐴 ∈ V ∧ 𝐵 ∈ V ) ) |