Description: A general instance of Theorem *5.11 of WhiteheadRussell p. 123. (Contributed by NM, 3-Jan-2005)
Ref | Expression | ||
---|---|---|---|
Assertion | pm5.11g | ⊢ ( ( 𝜑 → 𝜓 ) ∨ ( ¬ 𝜑 → 𝜒 ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm2.5g | ⊢ ( ¬ ( 𝜑 → 𝜓 ) → ( ¬ 𝜑 → 𝜒 ) ) | |
2 | 1 | orri | ⊢ ( ( 𝜑 → 𝜓 ) ∨ ( ¬ 𝜑 → 𝜒 ) ) |