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Thursday, February 02, 2012

 

Ex 4.30 Empty Power Sets

Given Ƥ, the power set function, and Ø, the empty set,what are Ƥ(Ø), Ƥ(Ƥ(Ø)) and Ƥ(Ƥ(Ƥ(Ø))) ?
How many members are there in Ƥ4(Ø) and Ƥ5(Ø) ?

Answers:
Ƥ1(Ø) = {Ø} cardinality: 20 = 1
Ƥ2(Ø) = {Ø,{Ø}} cardinality: 21 = 2
Ƥ3(Ø) = {Ø,{Ø},{{Ø}},{Ø,{Ø}}} cardinality: 22 = 4
Ƥ4(Ø) = {
Ø,
{Ø},
{{Ø}},
{{{Ø}}},
{Ø,{Ø}},
{Ø,{{Ø}}},
{{Ø,{Ø}}},
{{Ø},{{Ø}}},
{Ø,{Ø,{Ø}}},
{Ø,{Ø},{{Ø}}},
{{Ø},{Ø,{Ø}}},
{{{Ø}},{Ø,{Ø}}},
{Ø,{Ø},{Ø,{Ø}}},
{Ø,{{Ø}},{Ø,{Ø}}},
{{Ø},{{Ø}},{Ø,{Ø}}},
{Ø,{Ø},{{Ø}},{Ø,{Ø}}}
} cardinality: 24 = 16

There are 216 members in Ƥ5(Ø)


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