Theorem pm2.48 230

Description: Theorem *2.48 of [WhiteheadRussell] p. 107.

Assertion

Ref	Expression
pm2.48	⊢ (¬ (φ ∨ ψ) → (φ ∨ ¬ ψ))

Proof of Theorem pm2.48

Step	Hyp	Ref	Expression
1		pm2.46 229	. . 3 ⊢ (¬ (φ ∨ ψ) → ¬ ψ)
2	1	a1d 14	. 2 ⊢ (¬ (φ ∨ ψ) → (¬ φ → ¬ ψ))
3	2	orrd 203	1 ⊢ (¬ (φ ∨ ψ) → (φ ∨ ¬ ψ))

Syntax hints:  ¬ wn 1   → wi 2   ∨ wo 195

This theorem is referenced by:  pm2.85 439

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6

This theorem depends on definitions:  df-bi 128  df-or 197

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