Suhteline

Suhteline is a Finnish noun that can refer to a relation, connection, or proportion, depending on the context. In everyday language it covers relationships between people or things, as well as proportional or dependent connections in measurement and analysis. In mathematics the term is used to describe a relation from one set to another.

In mathematical usage, a relation R from a set A to a set B is a subset of the Cartesian product A × B. If a is related to b by R, this is written as aRb, meaning (a, b) ∈ R. Relations can have various properties: reflexive (every element a in A is related to itself), symmetric (if aRb then bRa), and transitive (if aRb and bRc then aRc). A relation that is reflexive, symmetric, and transitive is called an equivalence relation. A relation that is reflexive, antisymmetric, and transitive is a partial order.

A notable special case is a function, which is a relation where every element a in A is related to exactly one element b in B. Functions can thus be viewed as a subset of a relation with a uniqueness condition for the second component.

Other related concepts include relation composition and the inverse (converse) relation. In data modeling and relational databases, relations provide the foundational idea behind storing and querying connections between data items.

The term also appears in phrases such as cause-and-effect relations or proportional relations, reflecting its broad use to describe how entities connect, depend on, or compare with one another. Related Finnish terms include suhdeteema and suhde, which underlie the broader notion of connection or relationship.