Question

The number of possible subsets of a power set originating from a set with X number of element is given by the expression ____

(a) 2^X

(b) 2^X-1

(c) 2^2^x-1

(d) 2^2^x-2

I had been asked this question in class test.

This interesting question is from Interface Technologies in portion Software Defined Radio Architecture of Cognitive Radio

Answer 1

The correct choice is (d) 2^2^x-2

The best I can explain: The number of possible subsets of a power set originating from a set with X number of element is given by the expression 2^2^x-2. This expressed is referred as double exponential. It is not possible for all candidate topologies to be closed under union and finite intersection. It is necessary to define finite interface topologies more compactly.