We’re greatly saddened to hear of the death of Richard K. Guy yesterday morning. He was 103.

Richard K. Guy was a prolific collaborator. He co-authored four papers with Paul Erdős, worked frequently with John H. Conway and Elwyn Berlekamp, and was a frequent contributor to Martin Gardner’s Mathematical Games column.

The most well-known of Guy’s discoveries is the glider in Conway’s Game of Life.

He described himself as an amateur mathematician, often tackling problems that are best described as ‘recreational mathematics’. His work was not restricted to one area of maths, but often involved a combinatoric aspect.

Recreational mathematics occupied Guy’s mind for much longer than a normal lifetime, so you’ll have to take your pick from his bibliography. Fortunately, many of the problems and ideas that Guy wrote about can be tackled independently. *The Nesting and Roosting Habits of the Laddered Parenthesis* and *The Number-Pad Game* are two typical examples.

Two of the most approachable of Guy’s books are *Winning Ways for Your Mathematical Plays*, written with John H. Conway and Elwyn Berlekamp, and *The Book of Numbers*, written with John H. Conway.

We wrote a post on Guy’s 100th birthday, and the University of Calgary set up a page celebrating his life. Colm Mulcahy also wrote a long post summing up Guy’s first 100 years in his MAA blog.

Guy’s final book, *The Unity of Combinatorics*, co-authored with Ezra Brown, is due out in May from MAA Press.