Duality may refer to:

Mathematics

* Duality (mathematics), a mathematical concept ** Dual (category theory), a formalization of mathematical duality ** Duality (optimization) ** Duality (order theory), a concept regarding binary relations ** Duality (projective geometry), general principle of projective geometry **

Duality principle (Boolean algebra) In mathematics and mathematical logic, Boolean algebra is a branch of algebra. It differs from elementary algebra in two ways. First, the values of the variables are the truth values ''true'' and ''false'', usually denoted 1 and 0, whereas in ...

, the extension of order-theoretic duality to Boolean algebras **

S-duality (homotopy theory) In theoretical physics, S-duality (short for strong–weak duality, or Sen duality) is an equivalence of two physical theories, which may be either quantum field theories or string theories. S-duality is useful for doing calculations in theoret ...

Philosophy, logic, and psychology

Dualistic cosmology Dualism in cosmology or dualistic cosmology is the moral or spiritual belief that two fundamental concepts exist, which often oppose each other. It is an umbrella term that covers a diversity of views from various religions, including both traditi ...

, a twofold division in several spiritual and religious worldviews * Dualism (philosophy of mind), where the body and mind are considered to be irreducibly distinct * De Morgan's laws, specifically the ability to generate the dual of any logical expression * Complementary duality of Carl Jung's functions and types in Socionics

Science

Electrical and mechanical

* Duality (electrical circuits), regarding isomorphism of electrical circuits * Duality (mechanical engineering), regarding isomorphism of some mechanical laws

Physics

* AdS/CFT correspondence (anti de Sitter/conformal field theory correspondence), sometimes called the Maldacena duality *

Dual resonance model In theoretical physics, a dual resonance model arose during the early investigation (1968–1973) of string theory as an S-matrix theory of the strong interaction. Overview The dual resonance model was based upon the observation that the amplitud ...

* Duality (electricity and magnetism) * Englert–Greenberger duality relation * Holographic duality * Kramers–Wannier duality * * Mirror symmetry (string theory) *

Montonen–Olive duality Montonen–Olive duality or electric–magnetic duality is the oldest known example of strong–weak duality or S-duality according to current terminology. It generalizes the electro-magnetic symmetry of Maxwell's equations by stating that ma ...

* Mysterious duality * String duality, a class of symmetries ** S-duality ** T-duality ** U-duality * Wave–particle duality

Music

Albums

* ''Duality'' (Peter Leitch and John Hicks album), 1994 * ''Duality'' (Lisa Gerrard and Pieter Bourke album), 1998 * ''Duality'' (Set It Off album), 2014 * ''Duality'' (Ra album), 2005 * ''Duality'' (mixtape), 2012 * ''Duality'' (Luna Li album), 2022 * ''Duality'', a 2009 album by

Darker Half Darker-half is a heavy metal band from Sydney, led by vocalist Vo Simpson and known for their energetic live performances, their style has been described as power/thrash. History Singer/guitarist Vo Simpson started Darker Half in 2003 whi ...

* ''Duality'', a 2020 album by Duke Dumont * ''Duality'', a 2018 album by Big Scoob

Songs

* "Duality", a 2014 single from pop rock/punk rock band Set It Off * "Duality" (song), a 2004 single & Grammy-nominated song by metal band Slipknot * "Duality", a 2007 single from alternative rock/punk band Bayside

Other

* ''Duality'' (film), a 2001 Star Wars fan film by Dave Macomber and Mark Thomas * Duality, a large format audio mixing console by Solid State Logic * Duality (CoPs), refers to the notion of a duality in a Community of Practice * Dual (grammatical number), grammatical number that some languages use in addition to singular and plural