The up tack or falsum (⊥, \bot in LaTeX, U+22A5 in Unicode[1]) 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 wheel theory and lattice theory, which also represents absurdum when used for logical semantics
- The bottom type in type theory, which is the bottom element in the subtype relation. This may coincide with the empty type, which represents absurdum under the Curry–Howard correspondence
- The "undefined value" in quantum physics interpretations that reject counterfactual definiteness, as in (r0,⊥)
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[1]) is a binary relation symbol used to represent:
See also
Notes
- 1 2 "Mathematical Operators – Unicode" (PDF). Retrieved 2013-07-20.
- ↑ "Conditional independence notation". 27 March 2020.
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