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 co ...

, in the visual arts

Biology and medicine

Complement system The complement system, also known as complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and at ...

(immunology), a cascade of proteins in the blood that form part of innate immunity * Complementary DNA, DNA reverse transcribed from a mature mRNA template *

Complementarity (molecular biology) In molecular biology, complementarity describes a relationship between two structures each following the lock-and-key principle. In nature complementarity is the base principle of DNA replication and transcription as it is a property shared b ...

, a property whereby double stranded nucleic acids pair with each other *

Complementation (genetics) In genetics, complementation occurs when two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype (for example, a change in wing structure in flies) have offspring that express the wild-typ ...

, 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 and o ...

, a word or phrase having a particular syntactic role **

Subject complement In grammar, a subject complement or predicative of the subject is a predicative expression that follows a linking verb ( copula) and that complements the subject of the sentence by either (1) renaming it or (2) describing it. It completes the mea ...

, a word or phrase adding to a clause's subject after a linking verb *

Phonetic complement A phonetic complement is a phonetic symbol used to disambiguate word characters (logograms) that have multiple readings, in mixed logographic-phonetic scripts such as Egyptian hieroglyphs, Akkadian cuneiform, Japanese, and Mayan. Often they re ...

Complementary 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 ...

, a type of opposite in lexical semantics (sometimes called an antonym)

Mathematics

Algebra

Complement (group theory) In mathematics, especially in the area of algebra known as group theory, a complement of a subgroup ''H'' in a group ''G'' is a subgroup ''K'' of ''G'' such that :G = HK = \ \text H\cap K = \. Equivalently, every element of ''G'' has a unique expr ...

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), relating to decision problems and complexity classes *

Complement operator (regular expressions) A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of Character (computing), characters that specifies a pattern matching, search pattern in String (computer science), text. Usually s ...

* Method of complements, in computer science ** Radix complement ** Diminished radix complement ** Ones' complement ** Two's complement

Discrete mathematics

Complement graph In the mathematical field of graph theory, the complement or inverse of a graph is a graph on the same vertices such that two distinct vertices of are adjacent if and only if they are not adjacent in . That is, to generate the complement of a ...

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

Geometry

* Complementary angles *

Knot complement In mathematics, the knot complement of a tame knot ''K'' is the space where the knot is not. If a knot is embedded in the 3-sphere, then the complement is the 3-sphere minus the space near the knot. To make this precise, suppose that ''K'' is a ...

* Complement of a point, the dilation of a point in the centroid 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 In computer programming, a bitwise operation operates on a bit string, a bit array or a binary numeral (considered as a bit string) at the level of its individual bits. It is a fast and simple action, basic to the higher-level arithmetic operati ...

* 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 in e ...

Other uses

Complementary experiments In physics, two experimental techniques are often called complementary if they investigate the same subject in two different ways such that two different (ideally non-overlapping) properties or aspects can be investigated. For example, X-ray scatter ...

, 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. I ...

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