Theorem pm2.45 878

Description: Theorem *2.45 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.45	⊢ (¬ (𝜑 ∨ 𝜓) → ¬ 𝜑)

Proof of Theorem pm2.45

Step	Hyp	Ref	Expression
1		orc 863	. 2 ⊢ (𝜑 → (𝜑 ∨ 𝜓))
2	1	con3i 157	1 ⊢ (¬ (𝜑 ∨ 𝜓) → ¬ 𝜑)

Syntax hints:  ¬ wn 3   → wi 4   ∨ wo 843

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 209  df-or 844

This theorem is referenced by:  pm2.47  880  dn1  1052  eueq3  3702  outpasch  26535  acopyeu  26614  tgasa1  26638  unbdqndv2lem1  33843