Metamath Proof Explorer


Theorem pm5.11

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

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

Proof

Step Hyp Ref Expression
1 pm5.11g ( ( 𝜑𝜓 ) ∨ ( ¬ 𝜑𝜓 ) )