A deterministic variable is a variable representing a deterministic relation. In a relevance diagram, a variable is conditionally deterministic when it can be described by a deterministic function of a set of direct predecessors; it is unconditionally deterministic when it can be described by a constant. A deterministic variable can be viewed as a degenerate uncertain variable in which all conditional probability distributions are each totally concentrated on a single outcome.

See also: Unconditional Probability Distribution.