Schubert (1949) showed that every knot can be uniquely decomposed (up to the order in which the decomposition is performed) as a knot sum of a class of knots known as prime knots, which cannot themselves be further decomposed (Livingston 1993, p. 5; Adams 1994, pp.
The Moors were Muslim inhabitants of the Maghreb, the Iberian Peninsula, Sicily, and Malta during the Middle Ages.
The Moors in Spain were also famous as astronomers and mathematicians. Indeed, algebra comes from the Arabic al-jabr and the previously unknown, and critically important, Eastern concept of zero (probably originating from Babylonia) was introduced to Europe via Spain.