Now there's a question crying out for a nursery rhyme: When is a knot not a knot? Subscribe now for unlimited access . Login or signup to continue reading $ 0 / $ NaN /year All articles from our website & app The digital version of Today's Paper Breaking news alerts direct to your inbox Interactive Crosswords, Sudoku and Trivia All articles from the other regional websites in your area Continue To you and I, the answer is obvious. A knot is something to tie in your shoelace.
Which, of course, is not the same as a tangle. One is useful, while the other is the source of endless irritation. Note the use of the word "endless" - that's a plot point.
Aside from a method of fastening ropes, a knot might also refer to a nautical unit of speed or an imperfection in timber. The history of knots in rope would go back to any culture that ever developed a way of twining fibre. It's an extremely useful invention that is good for anything from constructing bags, hunting bows or a lasso.
Mathematician would argue a knot has no ends to tie or untie. Picture Shutterstock There's a vast array of types of knots, some useful and some merely decoration. In the Chinese Tang and Song Dynasty (960-1279 AD), they developed knots for handicraft, and Macramé is a popular form of art today.
So far it's not a particularly complicated story, but to a mathematician, our definition is...
loose. They would say a knot has no ends to tie or untie. In other words, a knot must be a loop that can cross over itse.
