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# duality

[doo-al-i-tee, dyoo-] /duˈæl ɪ ti, dyu-/
noun
1.
a dual state or quality.
2.
Mathematics. a symmetry within a mathematical system such that a theorem remains valid if certain objects, relations, or operations are interchanged, as the interchange of points and lines in a plane in projective geometry.
Origin
1350-1400
1350-1400; Middle English dualitie < Late Latin duālitās. See dual, -ity
Related forms
nonduality, noun
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for nonduality

## duality

/djuːˈælɪtɪ/
noun (pl) -ties
1.
the state or quality of being two or in two parts; dichotomy
2.
(physics) the principle that a wave-particle duality exists in microphysics in which wave theory and corpuscular theory are complementary. The propagation of electromagnetic radiation is analysed using wave theory but its interaction with matter is described in terms of photons. The condition of particles such as electrons, neutrons, and atoms is described in terms of de Broglie waves
3.
(geometry) the interchangeability of the roles of the point and the plane in statements and theorems in projective geometry
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Word Origin and History for nonduality

## duality

n.

late 14c., from Old French dualité (14c.), from Late Latin dualitas, from Latin dualis (see dual).

Online Etymology Dictionary, © 2010 Douglas Harper
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Encyclopedia Article for nonduality

## duality

in mathematics, principle whereby one true statement can be obtained from another by merely interchanging two words. It is a property belonging to the branch of algebra known as lattice theory, which is involved with the concepts of order and structure common to different mathematical systems. A mathematical structure is called a lattice if it can be ordered in a specified way (see order). Projective geometry, set theory, and symbolic logic are examples of systems with underlying lattice structures, and therefore also have principles of duality.

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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