 Each logical system, in its formal semantics, will include objects designed to represent ways the world pointed to by formulae in this system can be. Let these ways be denoted by \(W^i_{{\mathcal{L}_X}}\). When we aren’t concerned with which logical system is involved, we can simply write \(W^i\). To say that such a way models a formula \(\phi\) we write       \[     W_i \models \phi     \]   