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.
Raised Bogs Raised bogs are found almost exclusively in central Ireland, chiefly in the Shannon basin. There are a few examples in Ulster and Munster, but the vast majority are to found in the midlands. Unlike blanket bogs, they were formed naturally. One of Ireland's most characteristic features is the bog. Covering 1,200,000 hectares (1/6th) of the island, Ireland contains more bog, relatively speaking, than any country in Europe except Finland. Across Europe, as well as in Ireland, bogs have been exploited in recent centuries as a source of fuel.