Theorem xor3 385

Description: Two ways to express "exclusive or". (Contributed by NM, 1-Jan-2006.)

Assertion

Ref	Expression
xor3	⊢ (¬ (𝜑 ↔ 𝜓) ↔ (𝜑 ↔ ¬ 𝜓))

Proof of Theorem xor3

Step	Hyp	Ref	Expression
1		pm5.18 384	. . 3 ⊢ ((𝜑 ↔ 𝜓) ↔ ¬ (𝜑 ↔ ¬ 𝜓))
2	1	con2bii 360	. 2 ⊢ ((𝜑 ↔ ¬ 𝜓) ↔ ¬ (𝜑 ↔ 𝜓))
3	2	bicomi 227	1 ⊢ (¬ (𝜑 ↔ 𝜓) ↔ (𝜑 ↔ ¬ 𝜓))

This proof depends on syntax axioms:  ¬ wn 3   ↔ wb 209

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

This theorem is used by:  nbbnOLD  387  pm5.15  1030  nbi2  1033  xorass  1545  hadnot  1632  had0  1634  nabbib  3064  vn0OLD  4295  nmogtmnf  31429  nmopgtmnf  32527  dfac16  35887  maxssj0  36047  limsucncmpi  37448  wl-3xorbi  38664  wl-3xornot  38672  oneptri  44520  oaordnrex  44558  omnord1ex  44567  oenord1ex  44578  aiffnbandciffatnotciffb  48247  axorbciffatcxorb  48248  abnotbtaxb  48258  afv2orxorb  48571  line2ylem  50194  line2xlem  50196