Metamath Proof Explorer


Theorem 19.29r

Description: Variation of 19.29 . (Contributed by NM, 18-Aug-1993) (Proof shortened by Wolf Lammen, 12-Nov-2020)

Ref Expression
Assertion 19.29r x φ x ψ x φ ψ

Proof

Step Hyp Ref Expression
1 pm3.21 ψ φ φ ψ
2 1 aleximi x ψ x φ x φ ψ
3 2 impcom x φ x ψ x φ ψ