Find 881 points in the plane so that the lines between them determine as few different slopes as possible. Of course, they must not all be on a straight line.For example: 3 points determine 3 slopes. Four points forming a square determine 6 segments, but only 4 distinct slopes. (Proof of optimality not requried -- though it is known.)

Source: A beautiful new book titled: "Problems from the Book" by Aigner & Ziegler (Springer-Verlag). The "book" refers to Erdos's mythical book that contains the BEST proofs of everything.

## SNOW NEWS

A report, with photo, of our mathematical entry at the 1999 Breckenridge Snow Sculpture Championships appeared in the Feb. 5 issue of SCIENCE.

## WELCOME ROB

I am leaving town for several weeks. The PoW program will be administered by my colleague Rob Leduc (leduc@macalester.edu) in my absence.© Copyright 1999 Stan Wagon. Reproduced with permission.

23 February 1999