Thumbnails

Derrick Niederman, of Charleston, S.C., recently retired from the mathematics department at the College of Charleston, is the author of numerous books, including "Math Puzzles for the Clever Mind," "Number Freak: A Mathematical Compendium From 1 to 200" and a mystery novel, "A Killing on Wall Street."

This is his 14^th crossword for The Times (all Sundays), going back to 1983.

– puzzle by Derrick Niederman

Rich Katz, of Park City, Utah, does freelance work in corporate restructuring and bankruptcy liquidations. Jeff Chen, of Seattle, is a professional puzzlemaker and editor who's a frequent contributor here.

This puzzle started when one of them noticed the double entendre at 86-Across. They thought 116-Across made a nice exclamation point to the theme set.

– puzzle by Rich Katz and Jeff Chen

John Kugelman, of Gainesville, Va., is a software engineer and musician. Remarkably, this is his seventh Sunday Times crossword since January last year — by far the most of any contributor.

"All the time and creative energy I used to pour into music," he says, "now goes to crosswords. I used to spend my nights writing music. Now it's all crosswords, all the time. It seems to scratch the same itch."

– puzzle by John Kugelman

Daniel Grinberg, of Philadelphia, researches user experience for an energy company. Rafael Musa, of San Francisco, is a software engineer at Airbnb. They met last year at a crossword tournament and hit it off.

This is Daniel's seventh crossword for The Times and Rafael's 16^th. Most of Rafael's puzzles here have been collaborations. He says co-constructing "is a great way to get to know someone."

– puzzle by Daniel Grinberg and Rafael Musa