Metamath Proof Explorer


Theorem exp31

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

Ref Expression
Hypothesis exp31.1 φψχθ
Assertion exp31 φψχθ

Proof

Step Hyp Ref Expression
1 exp31.1 φψχθ
2 1 ex φψχθ
3 2 ex φψχθ