Research News Solving Knotty Problems in Math and Biology + See all authors and affiliations Science 28 Mar 1986:Vol. 231, Issue 4745, pp. 1506-1508DOI: 10.1126/science.231.4745.1506 GINA KOLATAFind this author on Google Scholar Find this author on PubMed Search for this author on this site Article Info & Metrics eLetters PDF This article has a correction. Please see:Erratum - May 16, 1986 This is a PDF-only article. The first page of the PDF of this article appears below.