relationer

Relationer is a term used across disciplines to describe a connection or association between objects. In mathematics, a relation on a set A is a subset of the Cartesian product A × A; more generally, a relation can relate any number of elements (an arity). A binary relation relates pairs of elements and serves as the basis for concepts such as orders, equivalence relations, and graphs.

Binary relations may have several properties. A relation is reflexive if every element relates to itself; it is symmetric if a relates to b implies b relates to a; it is transitive if a relates to b and b relates to c implies a relates to c. A function is a special kind of relation in which each first element is related to exactly one second element. Relations may also be nonreflexive, antisymmetric, or intransitive depending on the context.

In computing and data management, the relational model treats relations as tables. A table contains rows (tuples) and columns (attributes). Keys prevent ambiguity and enable connections between tables; primary keys identify rows and foreign keys link related tables. SQL is a common language used to query and modify relations in databases.

In the social sciences and network analysis, relationer denote ties between people, groups, or organizations. These relations can reflect friendship, kinship, collaboration, or influence. Analyzing the structure and dynamics of networks helps researchers understand phenomena such as community formation, information flow, and resilience.