CSFn

CSFn is an acronym that appears in several fields, without a single universally accepted meaning. In theoretical computer science and discrete mathematics, CSFn is often used to denote an n-ary constraint satisfaction function—a boolean-valued function F that takes an n-tuple of variable assignments and returns true if the constraints on those variables are satisfied. Such functions form part of constraint satisfaction problems (CSPs) and are used to define local constraints in algorithms and encodings.

In optimization and machine learning, CSFn can refer to a cost or objective function that has n components. In this sense, F could be a vector-valued function, or a scalar function aggregating n sub-functions, with the index n indicating the number of components or the particular member of a family of functions.

In software engineering and systems design, CSFn is sometimes used as a naming convention for a family of functions within a library, where n differentiates variants or versions of a function, such as CSFn1, CSFn2, etc. Usage is informal and library-specific.

Because CSFn is not standardized, readers should rely on the surrounding text to determine the intended meaning. Common cross-domain notes include: if discussing CSPs, interpret CSFn as an n-ary constraint function; if discussing optimization, interpret CSFn as an n-component cost function.

See also: CSP, cost function, function, network, constraint.