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Metamath Proof Explorer

Theorem pm5.14

Description: Theorem *5.14 of WhiteheadRussell p. 123. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm5.14 ( ( 𝜑 → 𝜓 ) ∨ ( 𝜓 → 𝜒 ) )

Proof

Step Hyp Ref Expression
1 pm2.521g ⊢ ( ¬ ( 𝜑 → 𝜓 ) → ( 𝜓 → 𝜒 ) )
2 1 orri ⊢ ( ( 𝜑 → 𝜓 ) ∨ ( 𝜓 → 𝜒 ) )