Metamath Proof Explorer


Theorem elmpocl2

Description: If a two-parameter class is not empty, the second argument is in its nominal domain. (Contributed by FL, 15-Oct-2012) (Revised by Stefan O'Rear, 7-Mar-2015)

Ref Expression
Hypothesis elmpocl.f ⊢ F = x ∈ A , y ∈ B ⟼ C
Assertion elmpocl2 ⊢ X ∈ S F T → T ∈ B

Proof

Step Hyp Ref Expression
1 elmpocl.f ⊢ F = x ∈ A , y ∈ B ⟼ C
2 1 elmpocl ⊢ X ∈ S F T → S ∈ A ∧ T ∈ B
3 2 simprd ⊢ X ∈ S F T → T ∈ B