Theorem pm2.49 737

Description: Theorem *2.49 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.49	⊢ (¬ (𝜑 ∨ 𝜓) → (¬ 𝜑 ∨ ¬ 𝜓))

Proof of Theorem pm2.49

Step	Hyp	Ref	Expression
1		pm2.46 734	. 2 ⊢ (¬ (𝜑 ∨ 𝜓) → ¬ 𝜓)
2	1	olcd 729	1 ⊢ (¬ (𝜑 ∨ 𝜓) → (¬ 𝜑 ∨ ¬ 𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ∨ wo 703

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-io 704

This theorem depends on definitions:  df-bi 116

This theorem is referenced by: (None)