Relatsioone

Relatsioone is a generic term describing a connection or association between two or more entities. In everyday use it encompasses relationships between people, objects, ideas, or events, and in formal contexts it refers to a precise relation with defined properties.

In mathematics and logic, a relation is a set of ordered pairs drawn from a domain, often called a binary relation. Examples include equality, the less-than relation, and the subset relation between sets. Relations can have properties such as reflexivity (every element relates to itself), symmetry (if a relates to b then b relates to a), and transitivity (if a relates to b and b relates to c, then a relates to c). They can be composed, inverted, and represented as graphs or relational matrices.

In databases and information systems, a relation is a table of values. The relational model uses relations with attributes and tuples. Operations from relational algebra such as selection, projection, join, and union manipulate relations to produce new relations.

In linguistics and semantics, relations express how entities participate in events or how words relate in meaning, such as agent-patient roles or part-whole relations, and they help model sentence structure and interpretation.

In social sciences and network theory, relational models study ties between actors, groups, and structures, using graphs to analyze connectivity, influence, and diffusion.

Because relations form a unifying concept across disciplines, they are often represented as sets of tuples, graphs, or matrices, enabling reasoning about compatibility, constraints, and interactions.

See also: relation algebra, graph theory, relational database, partial order, equivalence relation.