Theorem pm2.67 694

Description: Theorem *2.67 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.) (Revised by NM, 9-Dec-2012.)

Assertion

Ref	Expression
pm2.67	⊢ (((𝜑 ∨ 𝜓) → 𝜓) → (𝜑 → 𝜓))

Proof of Theorem pm2.67

Step	Hyp	Ref	Expression
1		pm2.67-2 666	1 ⊢ (((𝜑 ∨ 𝜓) → 𝜓) → (𝜑 → 𝜓))

Syntax hints:   → wi 4   ∨ wo 661

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-io 662

This theorem depends on definitions:  df-bi 115

This theorem is referenced by: (None)