Theorem pm1.2 768

Description: Axiom *1.2 (Taut) of [WhiteheadRussell] p. 96. (Contributed by NM, 3-Jan-2005.) (Revised by NM, 10-Mar-2013.)

Assertion

Ref	Expression
pm1.2	⊢ ((𝜑 ∨ 𝜑) → 𝜑)

Proof of Theorem pm1.2

Step	Hyp	Ref	Expression
1		id 19	. 2 ⊢ (𝜑 → 𝜑)
2	1, 1	jaoi 728	1 ⊢ ((𝜑 ∨ 𝜑) → 𝜑)

Syntax hints:   → wi 4   ∨ wo 720

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 721

This theorem depends on definitions:  df-bi 117

This theorem is referenced by:  oridm  769  sbequi  1892  swoer  6829