Metamath Proof Explorer


Theorem 3exp

Description: Exportation inference. (Contributed by NM, 30-May-1994) (Proof shortened by Wolf Lammen, 22-Jun-2022)

Ref Expression
Hypothesis 3exp.1 φ ψ χ θ
Assertion 3exp φ ψ χ θ

Proof

Step Hyp Ref Expression
1 3exp.1 φ ψ χ θ
2 1 3expa φ ψ χ θ
3 2 exp31 φ ψ χ θ