 Using the ternary relation \(R\), one can build models for different relevant logics. Starting with the basic relevant system \(\mathbf{B}\), one obtains models for stronger logics such as \(\mathbf{R}\), the system of relevant implication, by adding additional conditions on \(R\). (This is similar to the way we may move on from basic modal logic \(\mathbf{K}\) to the systems \(\mathbf{T}, \mathbf{S4}\), and \(\mathbf{S5}\), by adding extra conditions on the accessibility relation.) The constraints to be added to the ternary \(R\) are more complex than those of standard modal logic and some involve the star operator \({}^*\) (which we’ll address shortly).