For instance, we write $\{0\mathrm{.}6$ Alice, $0\mathrm{.}9$ Brian, $0\mathrm{.}4$ Fred, $0\mathrm{.}1$ Oscar, $0\mathrm{.}5$ Rita$\}$ for the set F $($of famous people$)$ to indicate that Alice has a $0\mathrm{.}6$ degree of membership in F$,$ Brian has a $0\mathrm{.}9$ degree of membership in F$,$ Fred has a $0\mathrm{.}4$ degree of membership in F$,$ Oscar has a $0\mathrm{.}1$ degree of membership in F$,$ and Rita has a $0\mathrm{.}5$ degree of membership in F $($so that Brian is the most famous and Oscar is the least famous of these people$).$ Also suppose that R is the set of rich people with R $=\{0\mathrm{.}4$ Alice, $0\mathrm{.}8$ Brian, $0\mathrm{.}2$ Fred, $0\mathrm{.}9$ Oscar, $0\mathrm{.}7$ Rita$\}.$