relácia

Relácia is a term used in several languages, including Slovak, Polish and Romanian, to denote a connection, linkage or relationship between entities. The word derives from Latin relatio and is applied across disciplines to describe how things are connected, whether in abstract structures such as sets and relations in logic, or in practical contexts such as communication, transport or kinship.

In mathematics and logic, a relation between sets A and B is defined as a subset of the Cartesian product A×B. A relation can be binary (between two elements) or of higher arity. It can have properties such as reflexivity, symmetry and transitivity. The composition of relations, inverse relations and the notion of equivalence relations are common topics under this heading. An everyday example is the less-than relation on numbers.

In computer science and information systems, a relation is central to the relational model of databases. A relation corresponds to a table, with columns as attributes and rows as tuples. Keys identify records, and foreign keys link relations. Relational algebra provides a formal set of operations—selection, projection, joins, and unions—to query and transform data.

In transport and scheduling, relácia can denote a route, connection or itinerary—the sequence of trips that constitutes a journey. In social contexts, it also means kinship or other types of relation between people, such as family ties, associations or dependencies.