The Gateway to Computer Science Excellence
First time here? Checkout the FAQ!
0 votes

asked in Set Theory & Algebra by Boss (7.3k points) | 95 views

1 Answer

+1 vote
Best answer
Answer (A) and (B).

Subset of a countable set is countable. Set of all integers is countable and hence any subset of it is also countable.

Power set of a finite set is finite and hence countable.
answered by Veteran (10.3k points)
Thank you
I doubt about A. How do you map the subset to a number line of integers?
Enumeration method:

Go in incresing order of absolute value. In a particular absolute value, go in increasing order of the value.

Start from |0| ->0.

Then |1| -> -1,1

Then |2| -> -2,2 and so on.

I think you meant

-1,1 -> |1|

-2,2 -> |2|

Thanks. Can you give me any good reference where the any ideas about how mappings are done is given?
As such I have no reference which I can give. I will try to find if there is any. Anyways, you an solve these type of questions intuitively.

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true

29,065 questions
36,871 answers
34,760 users