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↑