Theorem pm2.3 938

Description: Theorem *2.3 of [WhiteheadRussell] p. 104. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.3	⊢ ((𝜑 ∨ (𝜓 ∨ 𝜒)) → (𝜑 ∨ (𝜒 ∨ 𝜓)))

Proof of Theorem pm2.3

Step	Hyp	Ref	Expression
1		pm1.4 883	. 2 ⊢ ((𝜓 ∨ 𝜒) → (𝜒 ∨ 𝜓))
2	1	orim2i 924	1 ⊢ ((𝜑 ∨ (𝜓 ∨ 𝜒)) → (𝜑 ∨ (𝜒 ∨ 𝜓)))

This proof depends on syntax axioms:   → wi 4   ∨ wo 861

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 210  df-or 862

This theorem is used by:  meran1  37169  meran3  37171