a legal subset of the cross-product of the domains of a certain number of variables

a logical relation among several unknowns (or variable), each taking a value in a given domain

a mathematical representation in a mathematical programming problem of some situational factors that must be taken into consideration when an attempt is made to optimize a value function with respect to its key variables

a relation among program variables that is maintained throughout execution

a relation defined on some subset of these variables and denotes valid combinations of their values

a relation on instances of class Variable that should be maintained by the system during execution

a relationship to be maintained among a set of variables

Clause representing permissible Assignment s to Variables.

Constraint in information theory refers to the degree of statistical dependence between or among variables.