Metamath Proof Explorer


Theorem 3imp

Description: Importation inference. (Contributed by NM, 8-Apr-1994) (Proof shortened by Wolf Lammen, 20-Jun-2022)

Ref Expression
Hypothesis 3imp.1 φψχθ
Assertion 3imp φψχθ

Proof

Step Hyp Ref Expression
1 3imp.1 φψχθ
2 1 imp31 φψχθ
3 2 3impa φψχθ