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Opinion

Puzzled: Understanding Relationships Among Numbers

Welcome to three new challenging mathematical puzzles. Solutions to the first two will be published next month; the third is as yet (famously) unsolved. In each puzzle, the issue is how numbers interact with one another.
Opinion

Puzzled: Solutions and Sources

Last month (February 2009, p. 104) we posed a trio of brain teasers concerning algorithm termination. Here, we offer some possible solutions. How did you do?
Opinion

Puzzled: Will My Algorithm Terminate?

Welcome to three new challenging mathematical puzzles. Solutions to the first two will be published next month; the third is as yet unsolved. In them all, I concentrate on algorithm termination, outlining some simple procedures and asking whether they always terminate or might possibly run forever.
Opinion

Puzzled: Solutions and Sources

Last month (November 2008, p. 112) we posed a trio of brain teasers concerning circular food shapes. Here, we offer some possible solutions. How did you do?
Opinion

Puzzled: Circular Food

Welcome to three new challenging mathematical puzzles. Solutions to the first two will be published next month; the third is as yet unsolved, so you may need extra luck with that one. Here, I concentrate on circular food, so you might want to eat something before jumping in.
Opinion

Puzzled: Solutions and Sources

Last month (August 2008, p. 104) Peter Winkler posed a trio of brain teasers in his "Puzzled" column. Here, he offers some solutions. How well did you do?
Opinion

Puzzled: Delightful Graph Theory

Welcome to the new puzzle column. Each column will present three puzzles. The first two will have known (and usually elegant) solutions that will appear in the next issue of Communications. The third will be an open problem; good luck with that one. Readers are encouraged to submit prospective puzzles for future columns to puzzled@cacm.acm.org. We start with three delightful graph-theoretic puzzles. Here we go.

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