Metamath Proof Explorer


Theorem r19.28v

Description: Restricted quantifier version of one direction of 19.28 . (Assuming F/_ x A , the other direction holds when A is nonempty, see r19.28zv .) (Contributed by NM, 2-Apr-2004) (Proof shortened by Wolf Lammen, 17-Jun-2023)

Ref Expression
Assertion r19.28v φxAψxAφψ

Proof

Step Hyp Ref Expression
1 id φφ
2 1 ralrimivw φxAφ
3 2 anim1i φxAψxAφxAψ
4 r19.26 xAφψxAφxAψ
5 3 4 sylibr φxAψxAφψ