# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Loopy Solution Brings Infinite Relief," by Charles Seife. *Science,* 9February 2001.

How long does it take to untangle a tangle? Mathematicians have been studyingthis question for years in the field of knot theory, with no definitive answer.Lately there has been a step in the right direction---Jeffrey Lagarias of AT&Tand Joel Hass of the University of California, Davis have proved that onlyfinitely many moves are required to untangle the simplest knot of all, a loopof string called the unknot. While the bound on the number of moves isridiculously large, the proof of the existence of this limit is inspiringfurther research.

*--- Benjamin Stein *