 For any propositional constant, \(p\), and any moment in TIME, \(t\), there is a truth-value, \(\TRUE(p,t)\). This means that the truth-value of a propositional constant does not vary with the chronicles. The truth-value of a propositional constant depends only on the moment. On this basis the truth-value of any well formed formula (wff) has to be defined recursively. In the following sections we shall see that this can be done in several different ways.