The up tack or falsum (⊥,

/ref>

** See also **

*Plus and minus signs#Alternative plus sign|Alternative plus sign
* Contradiction
* List of mathematical symbols
* Tee (symbol) (⊤)
* Verum

** Notes **

{{Common logical symbols
Category:Mathematical notation
Category:Mathematical symbols
Category:Logic symbols

`\bot`

in LaTeX, U+22A5 in Unicode) is a constant symbol used to represent:
* The truth value 'false', or a logical constant denoting a proposition in logic that is always false (often called "falsum" or "absurdum").
* The bottom element in lattice theory, which also represents absurdum when used for logical semantics
* The bottom type in type theory, which also represents absurdum under the Curry–Howard correspondence
as well as
* Mixed radix decoding in the APL programming language
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). Tee 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
* Coprimality in number theory
The double tack up symbol (⫫, U+2AEB in Unicode) is a constant symbol used to represent:
* Conditional independence of random variables in probability theory/ref>