Theorem pm5.17 1009

Description: Theorem *5.17 of [WhiteheadRussell] p. 124. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 3-Jan-2013.)

Assertion

Ref	Expression
pm5.17	⊢ (((𝜑 ∨ 𝜓) ∧ ¬ (𝜑 ∧ 𝜓)) ↔ (𝜑 ↔ ¬ 𝜓))

Proof of Theorem pm5.17

Step	Hyp	Ref	Expression
1		bicom 225	. 2 ⊢ ((𝜑 ↔ ¬ 𝜓) ↔ (¬ 𝜓 ↔ 𝜑))
2		dfbi2 478	. 2 ⊢ ((¬ 𝜓 ↔ 𝜑) ↔ ((¬ 𝜓 → 𝜑) ∧ (𝜑 → ¬ 𝜓)))
3		orcom 867	. . . 4 ⊢ ((𝜑 ∨ 𝜓) ↔ (𝜓 ∨ 𝜑))
4		df-or 845	. . . 4 ⊢ ((𝜓 ∨ 𝜑) ↔ (¬ 𝜓 → 𝜑))
5	3, 4	bitr2i 279	. . 3 ⊢ ((¬ 𝜓 → 𝜑) ↔ (𝜑 ∨ 𝜓))
6		imnan 403	. . 3 ⊢ ((𝜑 → ¬ 𝜓) ↔ ¬ (𝜑 ∧ 𝜓))
7	5, 6	anbi12i 629	. 2 ⊢ (((¬ 𝜓 → 𝜑) ∧ (𝜑 → ¬ 𝜓)) ↔ ((𝜑 ∨ 𝜓) ∧ ¬ (𝜑 ∧ 𝜓)))
8	1, 2, 7	3bitrri 301	1 ⊢ (((𝜑 ∨ 𝜓) ∧ ¬ (𝜑 ∧ 𝜓)) ↔ (𝜑 ↔ ¬ 𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 209   ∧ wa 399   ∨ wo 844

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 210  df-an 400  df-or 845

This theorem is referenced by:  nbi2  1013  odd2np1  15755  ordtconnlem1  31408  sgnneg  32039