programming language Language in which a computer program¬ mer writes instructions for a computer to execute. Some languages, such
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1552 I Progressive Conservative Party of Canada ► proletariat
as COBOL, FORTRAN, Pascal, and C, are known as procedural languages because they use a sequence of commands to specify how the machine is to solve a problem. Others, such as LISP, are functional, in that program¬ ming is done by invoking procedures (sections of code executed within a program). Languages that support object-oriented programming take the data to be manipulated as their point of departure. Programming languages can also be classified as high-level or low-level. Low-level languages address the computer in a way that it can understand directly, but they are very far from human language. High-level languages deal in concepts that humans devise and can understand, but they must be translated by means of a compiler into language the computer understands.
Progressive Conservative Party of Canada Former Canadian political party. It was formed as the Liberal-Conservative Party in 1854 from a union of conservative and moderate-liberal political factions; except for a period during and after World War I, the party kept this name until 1942, when it adopted the name Progressive Conservative Party of Canada. Its first leader was John Macdonald. The party led the govern¬ ment from 1854 to 1873 and again from 1878 to 1896. It regained power in coalition with the Quebec nationalists in 1911 but went down to severe defeat in 1921. From then until 1957 the party held power only twice, briefly in 1926 and from 1930 to 1935. The party held power from 1958 to 1963 under John G. Diefenbaker, from 1979 to 1980 under Joe Clark, and from 1984 to 1989 under Brian Mulroney. In 1993 it was reduced to only two seats in the Canadian House of Commons. In 2003 the Progres¬ sive Conservative Party merged with the Canadian Alliance to form the Conservative Party of Canada. The party favoured reducing government intervention in both the economy and social affairs; strongly federalist, it also was less accommodating than other parties to Quebec separatism.
progressive education Movement that took form in Europe and North America during the late 19th century as a reaction to the alleged narrowness and formalism of traditional education. A main objective was to educate the “whole child”—that is, to attend to physical and emotional as well as intellectual growth. Creative and manual arts gained impor¬ tance in the curriculum, and children were encouraged toward experi¬ mentation and independent thinking. Progressive educational ideas and practices were most powerfully advanced in the U.S. by John Dewey. See also SuMMERHILL SCHOOL.
Progressive Party U.S. independent political party. The first Progres¬ sive Party, known as the Bull Moose Party, was organized in 1911. The second was assembled in 1924; it nominated as its presidential candidate Robert La Follette, who received 17% of the national vote on a platform calling for a “housecleaning” of executive departments, public control of natural resources, public ownership of the railways, and tax reduction. The party dissolved upon La Follette’s death in 1925. The third Progres¬ sive Party, founded in 1947 by Henry Wallace, differed from the previous groups in its focus on foreign affairs; it favoured a conciliatory policy toward the Soviet Union. Though Wallace received more than one mil¬ lion votes in the 1948 election, the party was never again influential.
progressive tax Tax levied at a rate that increases as the quantity subject to taxation increases. Designed to collect a greater proportion of tax revenue from wealthy people, progressive taxes reflect the view that those who are able to pay more should carry a heavier share of the tax burden. Progressive income taxes may provide for exemption from tax liability for incomes under a specified amount, or they may establish pro¬ gressively greater rates for larger and larger incomes. The presence of deductions can also make a tax progressive. Progressive taxes are a sta¬ bilizing force in periods of inflation or recession because the amount of tax revenue changes more than proportionately with an increase or decrease in income. For example, in an inflationary economy, as prices and incomes rise, a greater percentage of taxpayers’ income goes toward taxes. Government revenues increase, and the government has more lever¬ age over the economy. A side effect of this system is that lower-income taxpayers have an especially difficult time making ends meet when infla¬ tion is high. To compensate, many economists advocate indexation; sev¬ eral countries adjust their tax rates annually in times of inflation, usually in line with the consumer price index. See also regressive tax.
Prohibition Legal prevention of the manufacture, sale, or transporta¬ tion of alcoholic beverages. In the U.S., the Prohibition movement arose out of the religious revivalism of the 1820s. Maine passed the first state Prohibition law in 1846, ushering in a wave of such state legislation. The drive toward national Prohibition was fueled by the Anti-Saloon League,
founded in 1893. With Prohibition already adopted in 33 states, the 18th Amendment to the U.S. Constitution went into effect in 1920. Prohibition was embraced with varying degrees of enthusiasm in different parts of the country, and enforced accordingly. In urban areas, bootlegging gave rise to organized crime, with such gangsters as Al Capone. In part because of the rise in crime, its supporters gradually became disenchanted with it. The 21st Amendment repealed the 18th in 1933, and by 1966 all states had also abandoned Prohibition.
Prohibition Party Oldest minor U.S. political party still in existence. It was founded in 1869 to campaign for legislation to prohibit the manu¬ facture and sale of liquor. The party was strong in rural regions and among small-town voters affiliated with Protestant evangelical churches. It nomi¬ nated candidates for state and local offices and attained national strength in the 1888 and 1892 presidential elections, when its candidates polled 2.2% of the vote. Since 1900 it has been active mainly on local levels.
projective geometry Branch of mathematics that deals with the rela¬ tionships between geometric figures and the images (mappings) of them that result from projection. Examples of projections include motion pic¬ tures, maps of the Earth’s surface, and shadows cast by objects. One stimulus for the subject’s development was the need to understand per¬ spective in drawing and painting. Every point of the projected object and the corresponding point of its image must lie on the projection ray, a line that passes through the centre of projection. Modem projective geometry emphasizes the mathematical properties (such as straightness of lines and points of intersection) preserved in projections despite the distortion of lengths, angles, and shapes.
prokaryote \pro-'kar-e-,ot\ Any cellular organism that lacks a distinct nucleus. Bacteria (including blue-green algae, or cyanobacteria) are prokaryotes; all other organisms are eukaryotes. Prokaryotic cells lack a nuclear membrane and most of the components of eukaryotic cells. The cytoplasm includes ribosomes that carry out protein synthesis and a double-stranded DNA chromosome, usually circular. Many prokaryotes also contain additional circular DNA molecules called plasmids. The fla¬ gella are distinct from those of eukaryotes in design and movement.
Prokofiev \pr3-'k6-fyif\, Sergey (Sergeyevich) (b. April 23,1891, Sontsovka, Ukraine, Russian Empire—d. March 5, 1953, Moscow, Rus¬ sia, U.S.S.R.) Russian composer and pianist. Son of a pianist, he began writing piano pieces at age five and wrote an opera at nine. He studied at the St. Petersburg Conservatory (1904-14) with Nikolay Rimsky-Korsakov and others. Prolific and arrogant, from 1910 he made a living by perform¬ ing as a virtuoso. He played his own first concerto at his graduation recital. During World War I he wrote his Scythian Suite (1915) and First (“Clas¬ sical”) Symphony (1917). His opera The Love for Three Oranges pre¬ miered in 1921 in Chicago. Paris was his base from 1922, and during the 1920s he produced three new symphonies and the operas The Fiery Angel (1927) and The Gambler (1928). In the 1930s he was drawn back to his homeland; there he wrote the score for the ballet Romeo and Juliet (1936), the symphonic children’s tale Peter and the Wolf (1936), and striking national music for Sergey Eisenstein’s film Alexander Nevsky (1938). World War II inspired the score to Eisenstein’s Ivan the Terrible (1942—45) and the opera War and Peace (1943). The government’s denunciation of his work in 1948 was a harsh blow; his health failed, and he died on the same day as Joseph Stalin.