Theorem pm2.25 887

Description: Theorem *2.25 of [WhiteheadRussell] p. 104. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.25	⊢ (𝜑 ∨ ((𝜑 ∨ 𝜓) → 𝜓))

Proof of Theorem pm2.25

Step	Hyp	Ref	Expression
1		orel1 886	. 2 ⊢ (¬ 𝜑 → ((𝜑 ∨ 𝜓) → 𝜓))
2	1	orri 859	1 ⊢ (𝜑 ∨ ((𝜑 ∨ 𝜓) → 𝜓))

Syntax hints:   → wi 4   ∨ wo 844

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 206  df-or 845

This theorem is referenced by: (None)