Category Archives: problems and puzzles


It’s been almost a year since Bill Gasarch gave us the problem of four-coloring the nodes of a 17 × 17 grid in such a way that no rectangle has all four corners the same color. (See my earlier commentary … Continue reading

Posted in computing, mathematics, problems and puzzles | 2 Comments

Four questions about fuzzy rankings

The National Research Council is getting ready to release a new assessment of graduate-education programs in the U.S. The previous study, published in 1995, gave each Ph.D.-granting department a numerical score between 0 and 5, then listed all the programs … Continue reading

Posted in computing, games, mathematics, problems and puzzles, statistics | 22 Comments

A twist of fate

The school of philosophy called Antipodianism briefly flourished on the fringes of the Hellenistic world more than 2,000 years ago. The sect held that every person has an opposite number, a mirror image who inverts all our beliefs, feelings, actions … Continue reading

Posted in problems and puzzles | 6 Comments

A shy woodland creature

Martin Gardner died over the weekend. He was 95 and living in Norman, Oklahoma, not too far from his birthplace in Tulsa. Like many others, I grew up on Martin’s “Mathematical Games” column in Scientific American. Later I joined the … Continue reading

Posted in games, problems and puzzles | 5 Comments

Gruenberger’s prime path

Fred Gruenberger may well have been the first blogger on computational topics. When he was writing, back in the 1970s, there was no RSS, and so he distributed his musings in a monthly newsletter called Popular Computing. A typical issue … Continue reading

Posted in computing, mathematics, problems and puzzles | 8 Comments