Powersets A powerset is a set of sets s=a, b,c) Powerset of S= the set of all the subsets ofS, P(S), 2 2S={Q,{a},{b},{c},{a,b},{a,c},{b,c},{a,b,c}} Observation: 2S=2S(8=23)Powersets A powerset is a set of sets Powerset of S = the set of all the subsets of S， P（S），2 S S = { a, b, c } 2 S = { , {a}, {b}, {c}, {a, b}, {a, c}, {b, c}, {a, b, c} } Observation: | 2S | = 2|S| ( 8 = 23 )