The syntactic elements of the extension are discussed, and the semantics is described in terms of the properties of time dependent valuations of variables.
A system state is a valuation of all variables in.
Given an XML-database schema S (_{mathrm{XML}}), an XML-database is any valuation of these variables.
A formula such as πr² for the area of a circle of radius r describes infinitely many possible computations, one for each possible valuation of its variables.
Laws are always true; while they have the same form as constraints they constrain only vacuously in that every valuation of their variables is a solution.
This means, informally, that for every subset K of k outputs, every possible valuation of the variables in K is reachable.
(Valuation of a variable means the assignment of concrete values to it. The valuation of an expression means the assignment of concrete values to all variables within the expression).
Through valuation or binding of variables, a generic document type hierarchy can be brought into existence.
A state s, which is a valuation of the two variables v1 and v2, is represented as (v1[s], v2[s]).
A configuration of an EFSM is a pair of a (control) state and a valuation of the context variables (called context).
