Theorem pm2.36 816

Description: Theorem *2.36 of [WhiteheadRussell] p. 105. (Contributed by NM, 6-Mar-2008.)

Assertion

Ref	Expression
pm2.36	⊢ ((ψ → χ) → ((φ ∨ ψ) → (χ ∨ φ)))

Proof of Theorem pm2.36

Step	Hyp	Ref	Expression
1		pm1.4 375	. 2 ⊢ ((φ ∨ ψ) → (ψ ∨ φ))
2		pm2.38 815	. 2 ⊢ ((ψ → χ) → ((ψ ∨ φ) → (χ ∨ φ)))
3	1, 2	syl5 28	1 ⊢ ((ψ → χ) → ((φ ∨ ψ) → (χ ∨ φ)))

This proof depends on syntax axioms:   → wi 4   ∨ wo 357

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

This proof depends on definitions:  df-bi 177  df-or 359  df-an 360

This theorem is used by: (None)