Let $P = \{ U . S \cdot \text { presidents } \} , \quad O = \text { Obama, } W = \text { Washington, } J = \text { Jones }$

Let $P = \{ U . S \cdot \text { presidents } \} , \quad O = \text { Obama, } W = \text { Washington, } J = \text { Jones }$ . $$J \in P$$