Metamath Proof Explorer


Theorem pm5.11g

Description: A general instance of Theorem *5.11 of WhiteheadRussell p. 123. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm5.11g ( ( 𝜑𝜓 ) ∨ ( ¬ 𝜑𝜒 ) )

Proof

Step Hyp Ref Expression
1 pm2.5g ( ¬ ( 𝜑𝜓 ) → ( ¬ 𝜑𝜒 ) )
2 1 orri ( ( 𝜑𝜓 ) ∨ ( ¬ 𝜑𝜒 ) )