Up tack

The up tack or falsum (⊥, \bot in LaTeX, U+22A5 in Unicode) is a constant symbol used to represent:

• The bottom element in lattice theory
• The bottom type in type theory
• A logical constant denoting contradiction in logic (false)

The glyph of the up tack appears as an upside-down tee symbol, and as such is sometimes called eet (the word "tee" in reverse).

The tee (⊤), also called down tack, plays a complementary or dual role in many of these theories.

The similar-looking perpendicular symbol (⟂, \perp in LaTeX, U+27C2 in Unicode) is a binary relation symbol used to represent:

• Perpendicularity of lines in geometry
• Orthogonality in linear algebra
• Independence of random variables in probability theory
• Comparability in order theory
• Coprimality in number theory

See also

• Tee (symbol) (⊤)
• Table of mathematical symbols
• Alternative plus sign
• List of mathematical symbols