## ACM Great Results

*A Puck-ish take on promised technological advances*

Wikimedia Commons source |

Knecht Ruprecht accompanies Santa Claus in Germany. He brings gifts to good children but lumps of coal to naughty ones. He is regarded more generally as the German counterpart to England’s Robin Goodfellow, aka. Puck. The Simpsons’ dog “Santa’s Little Helper” is named “Knecht Ruprecht” in the show’s German edition.

Today we do a nice-or-naughty riff on technological gifts suggested by yesterday’s ACM TechNews mailing.

Read more…

## Explanations and Explorations

*Comparing proofs for the Jaccard metric*

BetterExplained source |

Kalid Azad is the founder of the website *Better Explained*. It is devoted to explaining mathematical concepts. He also has written two books.

Today we discuss how some proofs provide a concise *explanation* whereas others promote *exploration* of related concepts.

Read more…

## Explaining The Jaccard Metric

*Why is it a metric?*

Composite of source 1, source 2 |

Paul Jaccard was a botanist who worked at ETH in Zurich during much of the first half of the 20th century. He created, or discovered, the similarity notion that became the Jaccard metric. Very neat having a metric named after you.

Today we discuss proofs and explanations that the metric is indeed a metric.

Read more…

## Transposing

*On the arithmetic complexity of the matrix transpose*

[ KKB ] |

Michael Kaminski, David Kirkpatrick, and Nader Bshouty are complexity theorists who together and separately have proved many wonderful theorems. They wrote an interesting paper recently—well not quite—in 1988 about the transpose operation.

Today we want to discuss an alternative proof of the main result of that paper.

Read more…

## A Tiebreak Win and the Problem of Draws

*Carlsen impressed in fast chess, but what of classical?*

Cropped from AFP/Getty source (Irish Times) |

Magnus Carlsen retained his title of World Chess Champion on Wednesday. He thumped the American challenger Fabiano 3-0 in a best-of-four tiebreak series of games played at Rapid time controls. Despite his having only one-fourth the standard thinking time, Carlsen’s quality in the tiebreakers was plausibly *higher* than in the twelve regulation games.

Today Dick and I congratulate Carlsen on his victory and discuss implications for future top-level competitions in chess. Read more…

## Far From a Turkey Shoot

*Chess and draws and explainable AI*

Guardian Live source |

Magnus Carlsen and Fabiano Caruana have drawn the first eleven games of their world championship chess match. One game of the regular match is left for Monday. If it, too, is drawn, then there will be a faster-paced tiebreaker series on Wednesday. **Update 11/26:** It was drawn.

Today we discuss the match and some of its implications for computers and explanations.

Read more…

## A Thanksgiving Treat

*Another proof that there are an infinite number of primes of a special form*

Cropped from Packard Fellow src |

Trevor Wooley is a professor of mathematics at the University of Bristol in the UK.

Today, Ken and I want to say our thanks and share some small amount of fun with you all.

Read more…