"Seven-Color Torus Series in Bead-Crochet: Bracelet 4," by Sophie Sommer (Colgate University, Hamilton, NY; Susan Goldstine (St. Mary’s College of Maryland, St. Mary’s City); Ellie Baker (Computer scientist/Artist, Lexington, MA)

Bead-crochet (glass beads, thread) , "11.25” x "11.25”, 2008-2009. One of a series of “map-coloring” bead-crochet bracelets. The first three are examples of maps on the torus where each of seven “countries” shares a border with all six others. Such patterns prove that at least seven colors are necessary for map coloring on the torus [Heawood]. The fourth bracelet design is an embedding of the complete graph on seven vertices [K7] on the torus. The artists wish to acknowledge the extraordinary seven-color torus designs by Norton Starr (painted hydrostone), Carolyn Yackel (crocheted yarn) and sarah-marie belcastro (knitted yarn), which inspired our development of these patterns in bead-crochet. "Bead-crochet bracelets are made by crocheting a strand of beads into a cylinder and sewing the ends together to form a torus. Visualizing finished designs from the linear strand or from 2-D patterns can be quite challenging. Our design explorations started with a desire to create novel patterns that went beyond those we found in books. Noting that bracelets are topological tori, Sophie and Ellie went hunting for mathematics to inspire new patterns and found Susan’s seven-color tori website. Susan joined the quest to design the ideal 7-color torus bracelet, adding mathematical insight that gave rise to more perfect symmetry and better understanding of the relationships between designs. The four bracelets represent our collective steps in this process. As a set, they enhance our enjoyment of the beauty of the patterns, the pleasure of the craft, and the insights that come from the puzzle-solving design process." --- http://faculty.smcm.edu/sgoldstine/torus7.html