Metamath Proof Explorer


Theorem imori

Description: Infer disjunction from implication. (Contributed by NM, 12-Mar-2012)

Ref Expression
Hypothesis imori.1 φ ψ
Assertion imori ¬ φ ψ

Proof

Step Hyp Ref Expression
1 imori.1 φ ψ
2 imor φ ψ ¬ φ ψ
3 1 2 mpbi ¬ φ ψ