Metamath Proof Explorer


Theorem imp42

Description: An importation inference. (Contributed by NM, 26-Apr-1994)

Ref Expression
Hypothesis imp4.1 φψχθτ
Assertion imp42 φψχθτ

Proof

Step Hyp Ref Expression
1 imp4.1 φψχθτ
2 1 imp32 φψχθτ
3 2 imp φψχθτ