Byzantine emperor (1081-1118) at the time of the First Crusade who founded the Comnenian dynasty and partially restored the strength of the empire after its defeats by the Normans and Turks in the 11th century.
Byzantine emperor from 1180 to 1183. Alexius was the son of Manuel I Comnenus and Maria, daughter of Raymond, prince of Antioch. When his father died on September 24, 1180, Alexius became emperor at the age of 11, with his ...
Byzantine emperor from 1195 to 1203. He was the second son of Andronicus Angelus, grandson of Alexius I. In 1195 he was proclaimed emperor by the troops; he captured his brother, the emperor Isaac II, at Stagira in Macedonia and ...
Byzantine emperor from 1203 to 1204. Alexius was the son of Emperor Isaac II. He regained control of his rights to the Byzantine throne with the help of the Fourth Crusade but was deposed soon after by a palace coup.
Byzantine emperor in 1204, son-in-law of Alexius III Angelus. He led a revolt against the coemperors Isaac II and Alexius IV, who were supported by the Fourth Crusade. He then became the last emperor of Byzantium before its overthrow and ...
Italian manufacturer of high-priced sports cars and other vehicles. The company was operated by the Italian government through its state holding company, IRI (Istituto per la Ricostruzione Industriale), until 1986, when it was sold to Fiat SpA. Headquarters are in ...
perennial, clover-like, leguminous plant of the pea family (Fabaceae), known for its tolerance of drought, heat, and cold; for the remarkable productivity and the quality of its herbage; and for its value in soil improvement. It is widely grown primarily ...
(Hypera postica), insect pest of the family Curculionidae (order Coleoptera). The adult is dark brown to black and tiny (3 mm [ 110 inch] long) and has the typical prominent snout used by weevils to bore the small holes in ...
Talmudic scholar who wrote a codification of the Talmud known as Sefer ha-Halakhot ("Book of Laws"), which ranks with the great codes of Maimonides and Karo.
Soviet physicist who, with Herbert Kroemer and Jack S. Kilby, was awarded the Nobel Prize for Physics in 2000 for their work that laid the foundation for the modern era of computers and information technology.
Italian tragic poet whose predominant theme was the overthrow of tyranny. In his tragedies, he hoped to provide Italy with dramas comparable to those of other European nations. Through his lyrics and dramas he helped to revive the national spirit ...
one of the 12 soil orders in the U.S. Soil Taxonomy. Alfisols are arable soils with water content adequate for at least three consecutive months of the growing season. Prior to cultivation they are covered with natural broad-leaved deciduous forest ...
civilian president of Argentina (1983-89) elected after eight years of military rule, leader of the moderate Radical Civic Union (Spanish: Union Civica Radical, or UCR).
the first set of astronomical tables prepared in Christian Europe. They enabled calculation of eclipses and the positions of the planets for any given time based on the Ptolemaic theory, which assumed that the Earth was at the centre of ...
any of the eight species of exclusively marine fishes constituting the family Berycidae (order Beryciformes). The family contains two genera, Beryx and Centroberyx. Representatives occur in deep-sea habitats of the Atlantic, Pacific, and Indian oceans.
king of Asturias from 739 to 757, probably the son-in-law of the first Asturian king, Pelayo. The rebellion of the Berber garrisons in Islamic Spain (741) and the civil strife there that followed gave him the opportunity to incorporate Galicia ...
king of Asturias from 791 to 842, the son of Fruela I. He had to face frequent and determined attacks by the armies of the emirate of Cordoba and was often defeated, but his doggedness saved Asturias from extinction. He ...
king of Aragon from 1285 to 1291, son of Peter III. A weak king, he was involved in an unsuccessful constitutional struggle with the Aragonese nobles. In 1287 he was compelled to grant the so-called "Privilegio de la Union," which ...
king of Aragon from 1327 to 1336, son of James II. He was well-intentioned but weak. His reign was marked by a serious revolt in Sardinia, which led to war with Genoa, and by the establishment of diplomatic relations with ...
king of Leon and Asturias from c. 926 to c. 931, the son of Ordono II and the successor of his uncle Fruela II. He became a monk, abdicated, and then thought better of it and tried to recover his ...
king of Leon from 1188 to 1230, son of Ferdinand II of Leon, and cousin of Alfonso VIII of Castile (next to whom he is numbered as a junior member of the family). A forceful personality, Alfonso IX was determined ...
king of Aragon (1416-58) and king of Naples (as Alfonso I, 1442-58), whose military campaigns in Italy and elsewhere in the central Mediterranean made him one of the most famous men of his day. After conquering Naples, he transferred his ...
king of Leon from 999 to 1028, son of Bermudo II. He came to the throne because the devastating campaigns of Almanzor (see Mansur, Abu 'Amir al-) had forced his father to accept Almanzor's de facto suzerainty over Leon. The ...
king of Leon (1065-70) and king of reunited Castile and Leon (1072-1109), who by 1077 had proclaimed himself "emperor of all Spain" (imperator totius Hispaniae). His oppression of his Muslim vassals led to the invasion of Spain ...
king of Leon and Castile from 1126 to 1157, son of Raymond of Burgundy and the grandson of Alfonso VI, whose imperial title he assumed. Though his reign saw the apogee of the imperial idea in medieval Spain and though ...
king of Wessex (871-899), a Saxon kingdom in southwestern England. He prevented England from falling to the Danes and promoted learning and literacy. Compilation of the Anglo-Saxon Chronicle began during his reign, c. 890.
elaborate gold ornament consisting of an enameled plaque with a figure held in place on one side by an engraved design and on the other by a gold fret of Old English words. The inscription reads, "Aelfred mec heht gewyrcan" ...
private, coeducational institution of higher learning in Alfred, New York, U.S. The university comprises the privately endowed Colleges of Liberal Arts and Sciences, Business, and Engineering and Professional Studies and the publicly funded New York State College of Ceramics, which ...
astrophysicist and winner, with Louis Neel of France, of the Nobel Prize for Physics in 1970 for his essential contributions in founding plasma physics-the study of plasmas (ionized gases).
members of a group of predominantly aquatic, photosynthetic organisms of the kingdom Protista. They range in size from the tiny flagellate Micromonas that is 1 micrometre (0.00004 inch) in diameter to giant kelp that reach 60 metres (200 feet) in ...
connoisseur of the arts and sciences, esteemed by the philosophers of the Enlightenment for his wide knowledge and elegant presentation of advanced ideas.
historical province of southern Portugal, corresponding to the modern administrative distrito of Faro, bounded by the Atlantic Ocean (south and west) and the lower Guadiana River (east). Much of the interior upland region is of low productivity and is sparsely ...
branch of mathematics in which arithmetical operations and formal manipulations are applied to abstract symbols rather than specific numbers. The notion that there exists such a distinct subdiscipline of mathematics, as well as the term algebra to denote it, resulted ...
branch of mathematics that deals with the general properties of numbers and the relations between them. Algebra is fundamental not only to all further mathematics and statistics but to the natural sciences, computer science, economics, and business. Along with writing, ...
mathematical discipline that deals with vectors and matrices and, more generally, with vector spaces and linear transformations. Unlike other parts of mathematics that are frequently invigorated by new ideas and unsolved problems, linear algebra is very well understood. Its value ...
branch of mathematics concerned with the general algebraic structure of various sets (such as real numbers, complex numbers, matrices, and vector spaces), rather than rules and procedures for manipulating their individual elements.
statement of the equality of two expressions formulated by applying to a set of variables the algebraic operations, namely, addition, subtraction, multiplication, division, raising to a power, and extraction of a root. Examples are x3 + 1 and (
study of the geometric properties of solutions to polynomial equations, including solutions in dimensions beyond three. (Solutions in two and three dimensions are first covered in plane and solid analytic geometry, respectively.)
real number for which there exists a polynomial equation with integer coefficients such that the given real number is a solution. Algebraic numbers include all of the natural numbers, all rational numbers, some irrational numbers, and complex numbers of the ...
