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.
Peat deposits are found in many places around the world, including northern Europe and North America, principally in Canada and the Northern United States. Here, too, occur some of the world's largest peatlands, including the West Siberian Lowland, the Hudson Bay Lowland, and the Mackenzie River Valley.