j R 2 le(x; y)g for every role name R a IG i = xi for every object name ai Figure 4.1 shows a tableau for the concept from Example 4.1.3. 4.2 Tableau for P LT L In this section we describe Wolper's (=-=Wolper, 1985-=-) tableau algorithm for PLT L satisfiability. Informally speaking, it attempts to construct a model for the input formula ' by generating a finite sequence of states (corresponding to time points) whi