 Hence, Peirce’s slightly modified addition sign, \(\cunion\) , denotes inclusive disjunction. “\(\unary{f} \cunion \unary{u}\)” denotes all those who are either a Frenchman or a violinist. The notation does not imply that no Frenchman is a violinist or no violinist is a Frenchman. Even though Peirce’s example is limited to unary predicates, we can extend the idea to binary. Using modern notation,   \[\binary{l} \cunion \binary{s}  = \{\langle x, y\rangle \mid lover(x, y) \lor servant(x,y)\}.\]    That is, it corresponds to a union of relations.