A complement is something that completes something else. Complement may refer specifically to:

The arts

* Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-class collections into complementary sets *

Complementary color Complementary colors are pairs of colors which, when combined or mixed, cancel each other out (lose hue) by producing a grayscale color like white or black. When placed next to each other, they create the strongest contrast for those two ...

, in the visual arts

Biology and medicine

* Complement system (immunology), a cascade of proteins in the blood that form part of innate immunity *

Complementary DNA In genetics, complementary DNA (cDNA) is DNA synthesized from a single-stranded RNA (e.g., messenger RNA ( mRNA) or microRNA (miRNA)) template in a reaction catalyzed by the enzyme reverse transcriptase. cDNA is often used to express a sp ...

, DNA reverse transcribed from a mature mRNA template * Complementarity (molecular biology), a property whereby double stranded nucleic acids pair with each other * Complementation (genetics), a test to determine if independent recessive mutant phenotypes are caused by mutations in the same gene or in different genes

Grammar and linguistics

Complement (linguistics) In grammar, a complement is a word, phrase, or clause that is necessary to complete the meaning of a given expression. Complements are often also arguments (expressions that help complete the meaning of a predicate). Predicative, subject an ...

, a word or phrase having a particular syntactic role ** Subject complement, a word or phrase adding to a clause's subject after a linking verb * Phonetic complement * Complementary, a type of opposite in lexical semantics (sometimes called an antonym)

Mathematics

Algebra

* Complement (group theory) *

Complementary subspaces In abstract algebra, the direct sum is a construction which combines several modules into a new, larger module. The direct sum of modules is the smallest module which contains the given modules as submodules with no "unnecessary" constraints, ma ...

* Orthogonal complement *

Schur complement In linear algebra and the theory of matrices, the Schur complement of a block matrix is defined as follows. Suppose ''p'', ''q'' are nonnegative integers, and suppose ''A'', ''B'', ''C'', ''D'' are respectively ''p'' × ''p'', ''p'' × ''q'', ''q'' ...

Algorithms

Complement (complexity) In computational complexity theory, the complement of a decision problem is the decision problem resulting from reversing the ''yes'' and ''no'' answers. Equivalently, if we define decision problems as sets of finite strings, then the complement o ...

, relating to decision problems and complexity classes * Complement operator (regular expressions) * Method of complements, in computer science ** Radix complement ** Diminished radix complement ** Ones' complement **

Two's complement Two's complement is a mathematical operation to reversibly convert a positive binary number into a negative binary number with equivalent (but negative) value, using the binary digit with the greatest place value (the leftmost bit in big- endian ...

Discrete mathematics

* Complement graph ** Self-complementary graph, a graph which is isomorphic to its complement * Complemented lattice

Geometry

* Complementary angles * Knot complement * Complement of a point, the dilation of a point in the

centroid In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the arithmetic mean position of all the points in the surface of the figure. The same definition extends to any ...

of a given triangle, with ratio −1/2

Logic

Complement (set theory) In set theory, the complement of a set , often denoted by (or ), is the set of elements not in . When all sets in the universe, i.e. all sets under consideration, are considered to be members of a given set , the absolute complement of is the ...

* Complementary event in probability * Logical complement * Bitwise complement * Complements in

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 ...

Other uses

* Complementary experiments, in physics *

Complement good In economics, a complementary good is a good whose appeal increases with the popularity of its complement. Technically, it displays a negative cross elasticity of demand and that demand for it increases when the price of another good decreases ...

(economics), a good often consumed together with another good * Ship's complement, the number of persons in a ship's company