Metamath Proof Explorer


Theorem 19.37

Description: Theorem 19.37 of Margaris p. 90. See 19.37v for a version requiring fewer axioms. (Contributed by NM, 21-Jun-1993)

Ref Expression
Hypothesis 19.37.1 x φ
Assertion 19.37 x φ ψ φ x ψ

Proof

Step Hyp Ref Expression
1 19.37.1 x φ
2 19.35 x φ ψ x φ x ψ
3 1 19.3 x φ φ
4 3 imbi1i x φ x ψ φ x ψ
5 2 4 bitri x φ ψ φ x ψ