Sets and Groups - March 2005, Stage 4&5

Problems

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Spot the Card

Stage: 4 Challenge Level: Challenge Level:1

It is possible to identify a particular card out of a pack of 15 with the use of some mathematical reasoning. What is this reasoning and can it be applied to other numbers of cards?

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Sheffuls

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Discover a handy way to describe reorderings and solve our anagram in the process.

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Zodiac

Stage: 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

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Groups of Sets

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

The binary operation * for combining sets is defined as the union of two sets minus their intersection. Prove the set of all subsets of a set S together with the binary operation * forms a group.

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What's a Group?

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

Explore the properties of some groups such as: The set of all real numbers excluding -1 together with the operation x*y = xy + x + y. Find the identity and the inverse of the element x.

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Binary Sequences

Stage: 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Show that the infinite set of finite (or terminating) binary sequences can be written as an ordered list whereas the infinite set of all infinite binary sequences cannot.