duality

nouns

being twofold; a classification into two opposed parts or subclasses
"the dichotomy between eastern and western culture"
is derived from
(physics) the property of matter and electromagnetic radiation that is characterized by the fact that some properties can be explained best by wave theory and others by particle theory
is derived from
(geometry) the interchangeability of the roles of points and planes in the theorems of projective geometry
domain category
the pure mathematics of points and lines and curves and surfaces
is a type of (narrower)
the quality of being capable of exchange or interchange