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 North York Moors consist of a moorland plateau, intersected by a number of deep dales or valleys containing cultivated land or woodland. The largest dale is Eskdale, the valley of the River Esk which flows from west to east and empties into the North Sea at Whitby. The Cleveland Hills rise north of Eskdale.