Pareto distributionThe Pareto distribution, named after the Italian civil engineer, economist, and sociologist Vilfredo Pareto, is a power-law probability distribution that is used in description of social, quality control, scientific, geophysical, actuarial, and many other types of observable phenomena; the principle originally applied to describing the distribution of wealth in a society, fitting the trend that a large portion of wealth is held by a small fraction of the population.
AverageIn ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of the numbers divided by how many numbers are in the list (the arithmetic mean). For example, the average of the numbers 2, 3, 4, 7, and 9 (summing to 25) is 5. Depending on the context, an average might be another statistic such as the median, or mode. For example, the average personal income is often given as the median—the number below which are 50% of personal incomes and above which are 50% of personal incomes—because the mean would be higher by including personal incomes from a few billionaires.
Urban warfareUrban warfare is warfare in urban areas such as towns and cities. Urban combat differs from combat in the open at both the operational and the tactical levels. Complicating factors in urban warfare include the presence of civilians and the complexity of the urban terrain. Urban combat operations may be conducted to capitalize on strategic or tactical advantages associated with the possession or the control of a particular urban area or to deny these advantages to the enemy.
Dead end (street)A dead end, also known as a cul-de-sac (ˈkʌldəsæk,_ˈkʊl-, from French for 'bag-bottom'), no through road or no exit road, is a street with only one inlet or outlet. "Dead end" is also understood in all varieties of English, but the official terminology and traffic signs include many different alternatives. Some of these are used only regionally. In the United States and other countries, cul-de-sac is often not an exact synonym for dead end and refers to dead ends with a circular end.
Uruk periodThe Uruk period (ca. 4000 to 3100 BC; also known as Protoliterate period) existed from the protohistoric Chalcolithic to Early Bronze Age period in the history of Mesopotamia, after the Ubaid period and before the Jemdet Nasr period. Named after the Sumerian city of Uruk, this period saw the emergence of urban life in Mesopotamia and the Sumerian civilization. The late Uruk period (34th to 32nd centuries) saw the gradual emergence of the cuneiform script and corresponds to the Early Bronze Age; it has also been described as the "Protoliterate period".
