Mathematical Digest

Short Summaries of Articles about Mathematics
in the Popular Press

"Spin Doctors," by Kurt Przybilla, and "Shape-Shifter," by Chuck Hoberman. In"Tops, Bots, and Yo-yos," Discover, June 2001.

In the "Toys" portion of the Re/views section, we catch a glimpseof newfangled mathematical tops: rubber balls glued together to maketetrahedrons, octahedrons, and icosahedrons all spin beautifully on anyexterior ball. Unlike conventional tops, they'll spin on many differentaxes.Hoberman's greatest claim to fame is his plastic expanding Hobermansphere, which smoothly alters its shape with a gentle tug. InSpetember, he introduced Gro-bots, a line of motorized playthings thatlets people assemble droves of pieces into continuously shape-shiftingcreatures.

--- Rafe Jones