The up tack or falsum (⊥, \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
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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