Theorem trunanfal 1581

Description: A ⊼ identity. (Contributed by Anthony Hart, 23-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.) (Proof shortened by Wolf Lammen, 10-Jul-2020.)

Assertion

Ref	Expression
trunanfal	⊢ ((⊤ ⊼ ⊥) ↔ ⊤)

Proof of Theorem trunanfal

Step	Hyp	Ref	Expression
1		df-nan 1487	. . 3 ⊢ ((⊤ ⊼ ⊥) ↔ ¬ (⊤ ∧ ⊥))
2		truanfal 1573	. . 3 ⊢ ((⊤ ∧ ⊥) ↔ ⊥)
3	1, 2	xchbinx 334	. 2 ⊢ ((⊤ ⊼ ⊥) ↔ ¬ ⊥)
4		notfal 1567	. 2 ⊢ (¬ ⊥ ↔ ⊤)
5	3, 4	bitri 274	1 ⊢ ((⊤ ⊼ ⊥) ↔ ⊤)

Syntax hints:  ¬ wn 3   ↔ wb 205   ∧ wa 396   ⊼ wnan 1486  ⊤wtru 1540  ⊥wfal 1551

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 206  df-an 397  df-nan 1487  df-tru 1542  df-fal 1552

This theorem is referenced by:  falnantru  1582