Mathematical Digest
Short Summaries of Articles about Mathematics in the Popular Press"Tying knots to tubular geometry, DNA loops," by Ivars Peterson.Science News, 16 November 1996, page 310. This article describes a novel technique that mathematicians have used toanalyze knots. A mathematical knot is usually thought of as a closed curvewith no thickness. In this new approach, a knot is viewed as a knotted pieceof tube that has a certain diameter. The diameter of the tube is then expandeduntil there is contact between different parts of the tube. Researchers havefound that there are connections between the length and diameter of the tubeand the number of crossings, as well as to the knotting behavior of DNA. Allyn Jackson
