Exercise 8.26

Write in first-order logic the assertion that every key and at least one of every pair of socks will eventually be lost forever, using only the following vocabulary: ${Key}(x)$, $x$ is a key; ${Sock}(x)$, $x$ is a sock; ${Pair}(x,y)$, $x$ and $y$ are a pair; ${Now}$, the current time; ${Before}(t_1,t_2)$, time $t_1$ comes before time $t_2$; ${Lost}(x,t)$, object $x$ is lost at time $t$.

View Answer