Metamath Proof Explorer


Theorem exp44

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

Ref Expression
Hypothesis exp44.1 φψχθτ
Assertion exp44 φψχθτ

Proof

Step Hyp Ref Expression
1 exp44.1 φψχθτ
2 1 exp32 φψχθτ
3 2 expd φψχθτ