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Questions › DSE › DSE 2005 › Q5
2 marks, −1Mathematics › Real analysis › Topology of the real line: open, closed and compact setsHardabout 3 min

DSE 2005 Question 5: Real analysis

Consider a Society consisting of individuals who may belong to sets called Clubs and/or Tribes, with the rules: the entire Society is a Club; the empty subset is a Club; given a collection of Clubs the set of individuals in at least one of them is a Club (arbitrary unions); given any two Clubs the set of individuals in both is a Club (finite intersections); and a set is a Tribe if and only if the set of individuals not in it constitutes a Club. The union of two Tribes is necessarily

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Real analysis has come up 38 times in 5 exams since 2005.

What this question tests

This question is on Topology of the real line: open, closed and compact sets, part of Real analysis in Mathematics.

Which sets are open, closed or compact and how unions and intersections behave.

TestStop has 29 past-paper questions on this subtopic.

Practise Real analysisMore on Topology of the real line: open, closed and compact sets

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Question from the DSE 2005 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.