Metamath Proof Explorer


Theorem elfzoelz

Description: Reverse closure for half-open integer sets. (Contributed by Stefan O'Rear, 14-Aug-2015)

Ref Expression
Assertion elfzoelz ⊢ A ∈ B ..^ C → A ∈ ℤ

Proof

Step Hyp Ref Expression
1 elfzoel1 ⊢ A ∈ B ..^ C → B ∈ ℤ
2 elfzoel2 ⊢ A ∈ B ..^ C → C ∈ ℤ
3 fzof ⊢ ..^ : ℤ × ℤ ⟶ 𝒫 ℤ
4 3 fovcl ⊢ B ∈ ℤ ∧ C ∈ ℤ → B ..^ C ∈ 𝒫 ℤ
5 1 2 4 syl2anc ⊢ A ∈ B ..^ C → B ..^ C ∈ 𝒫 ℤ
6 5 elpwid ⊢ A ∈ B ..^ C → B ..^ C ⊆ ℤ
7 id ⊢ A ∈ B ..^ C → A ∈ B ..^ C
8 6 7 sseldd ⊢ A ∈ B ..^ C → A ∈ ℤ