0 votes 0 votes Set Theory & Algebra set-theory&algebra + – KISHALAY DAS asked Dec 24, 2016 KISHALAY DAS 633 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 1 votes 1 votes 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. Samujjal Das answered Dec 24, 2016 Samujjal Das comment Share Follow See all 7 Comments See all 7 7 Comments reply KISHALAY DAS commented Dec 24, 2016 reply Follow Share Thank you 1 votes 1 votes Sushant Gokhale commented Dec 25, 2016 reply Follow Share I doubt about A. How do you map the subset to a number line of integers? 0 votes 0 votes Samujjal Das commented Dec 25, 2016 reply Follow Share 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. 0 votes 0 votes Sushant Gokhale commented Dec 25, 2016 reply Follow Share @GateSet I think you meant -1,1 -> |1| -2,2 -> |2| right? 0 votes 0 votes Samujjal Das commented Dec 25, 2016 reply Follow Share Exactly 0 votes 0 votes Sushant Gokhale commented Dec 25, 2016 reply Follow Share Thanks. Can you give me any good reference where the any ideas about how mappings are done is given? 0 votes 0 votes Samujjal Das commented Dec 25, 2016 reply Follow Share 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. 1 votes 1 votes Please log in or register to add a comment.