Metamath Proof Explorer


Theorem goelel3xp

Description: A "Godel-set of membership" is a member of a doubled Cartesian product. (Contributed by AV, 16-Sep-2023)

Ref Expression
Assertion goelel3xp ⊢ I ∈ ω ∧ J ∈ ω → I ∈ 𝑔 J ∈ ω × ω × ω

Proof

Step Hyp Ref Expression
1 goel ⊢ I ∈ ω ∧ J ∈ ω → I ∈ 𝑔 J = ∅ I J
2 peano1 ⊢ ∅ ∈ ω
3 2 a1i ⊢ I ∈ ω ∧ J ∈ ω → ∅ ∈ ω
4 opelxpi ⊢ I ∈ ω ∧ J ∈ ω → I J ∈ ω × ω
5 3 4 opelxpd ⊢ I ∈ ω ∧ J ∈ ω → ∅ I J ∈ ω × ω × ω
6 1 5 eqeltrd ⊢ I ∈ ω ∧ J ∈ ω → I ∈ 𝑔 J ∈ ω × ω × ω