2.3 Example 3

Let us consider something less formal. Let $P = \{Tom, John, Edward, Mark\}$ , and let $Q = \{Jane, Mary, Ashley, Bonnie\}$ . In this example, let us consider the relation of husband-wife. The relation $L \subseteq P \times Q$ . For example, $L = \{(Tom, Mary), (John, Ashley), (Mark, Bonnie), (Edward, Jane)\}$ . This means that Tom and Mary are married, John and Ashley, Mark and Bonnie, and Edward and Jane.