Theorem pm2.62 398

Description: Theorem *2.62 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 13-Dec-2013.)

Assertion

Ref	Expression
pm2.62	⊢ ((φ ∨ ψ) → ((φ → ψ) → ψ))

Proof of Theorem pm2.62

Step	Hyp	Ref	Expression
1		pm2.621 397	. 2 ⊢ ((φ → ψ) → ((φ ∨ ψ) → ψ))
2	1	com12 27	1 ⊢ ((φ ∨ ψ) → ((φ → ψ) → ψ))

Syntax hints:   → wi 4   ∨ wo 357

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 177  df-or 359

This theorem is referenced by:  dfor2  400