85 ways to tie a tie
My father taught me to tie a tie on my first day in high school. By the end of my first term, tying a tie had lodged itself in that part of my mind sometimes referred to as muscle memory. I don't know how I do it, I just do. It is the same type of memory that helps me touch type or drive a car.
Thomas Fink and Yong Mao, two Cambridge scientists, have shown that there are exactly 85 ways to tie a tie. Using Fink's encyclopaedia of knots I discovered that my father showed me how to tie knot number 31. That is an Li-Co-Ri-Lo-Ci-Ro-Li-Co-T for the mathematically inclined, or a Windsor knot as it is more commonly known.
According to Fink and Mao, the Windsor has some nice properties: (1) It consists of eight moves, not just three or four like some of its cousins; (2) It has three centre moves resulting in a wide knot; (3) It is nearly symmetrical. When the number of right moves are subtracted from the number of left moves, the result is one; (4) It is completely balanced. There is no switching back and forth between clockwise and counter-clockwise windings; (5) Finally, the Windsor's knotted status is negative. When it is loosened, removed over the head and the thin end pulled, it leaves no knot.
Two days to go till Christmas. What are the odds of getting a tie this year?