 Positive semantics with dual domains are generally the simplest. The members of the outer domain \(\bD_o\) typically represent “non-existing” things. Depending on the application, these may be theoretical or ideal entities, error objects (in computer science), fictional objects, merely possible (or even impossible) objects, and so on. Some authors make \(\bD\) a subset of \(\bD_o\), which is the convention throughout this article; others make the two disjoint. In a bivalent dual-domain semantics each singular term denotes an object in \(\bD_o\) though possibly not in \(\bD\). Thus \(\bD\), though not \(\bD_o\), may be empty. Predicates are assigned extensions from \(\bD_o\), and the truth-values of atomic formulas (whether empty-termed or not) are computed in the usual Tarskian fashion: an atomic formula is true if and only if the \(n\)-tuple of objects denoted by its singular terms, taken in order, is a member of the predicate’s extension. Identity statements are no exception. Statements of the form \(s=t\) are true if and only if \(s\) and \(t\) denote the same object. Hence, even if empty-termed, they may be true.