The abacus called a counting frame, is a calculating tool, in use in the ancient Near East, Europe and Russia, centuries before the adoption of the written Hindu–Arabic numeral system. The exact origin of the abacus is still unknown. Today, abacuses are constructed as a bamboo frame with beads sliding on wires, but they were beans or stones moved in grooves of sand or on tablets of wood, stone, or metal. Abacuses come in different designs; some designs, like the bead frame consisting of beads divided into tens, are used to teach arithmetic, although they remain popular in the post-Soviet states as a tool. Other designs, such as the Japanese soroban, have been used for practical calculations involving several digits. For any particular abacus design, there are numerous different methods to perform a certain type of calculation, which may include basic operations like addition and multiplication, or more complex ones, such as calculating square roots; some of these methods may work with non-natural numbers.

Although today many use calculators and computers instead of abacuses to calculate, abacuses still remain in common use in some countries. Merchants and clerks in some parts of Eastern Europe, Russia and Africa use abacuses, they are still used to teach arithmetic to children; some people who are unable to use a calculator because of visual impairment may use an abacus. The use of the word abacus dates before 1387 AD, when a Middle English work borrowed the word from Latin to describe a sandboard abacus; the Latin word came from Greek ἄβαξ which means something without base, improperly, any piece of rectangular board or plank. Alternatively, without reference to ancient texts on etymology, it has been suggested that it means "a square tablet strewn with dust", or "drawing-board covered with dust". Whereas the table strewn with dust definition is popular, there are those that do not place credence in this at all and in fact state that it is not proven. Greek ἄβαξ itself is a borrowing of a Northwest Semitic Phoenician, cognate with the Hebrew word ʾābāq, or "dust".

The preferred plural of abacus is a subject of disagreement, with both abaci in use. The user of an abacus is called an abacist; the period 2700–2300 BC saw the first appearance of the Sumerian abacus, a table of successive columns which delimited the successive orders of magnitude of their sexagesimal number system. Some scholars point to a character from the Babylonian cuneiform which may have been derived from a representation of the abacus, it is the belief of Old Babylonian scholars such as Carruccio that Old Babylonians "may have used the abacus for the operations of addition and subtraction. The use of the abacus in Ancient Egypt is mentioned by the Greek historian Herodotus, who writes that the Egyptians manipulated the pebbles from right to left, opposite in direction to the Greek left-to-right method. Archaeologists have found ancient disks of various sizes that are thought to have been used as counters. However, wall depictions of this instrument have not been discovered. During the Achaemenid Empire, around 600 BC.

Under the Parthian and Iranian empires, scholars concentrated on exchanging knowledge and inventions with the countries around them – India and the Roman Empire, when it is thought to have been exported to other countries. The earliest archaeological evidence for the use of the Greek abacus dates to the 5th century BC. Demosthenes talked of the need to use pebbles for calculations too difficult for your head. A play by Alexis from the 4th century BC mentions an abacus and pebbles for accounting, both Diogenes and Polybius mention men that sometimes stood for more and sometimes for less, like the pebbles on an abacus; the Greek abacus was a table of wood or marble, pre-set with small counters in wood or metal for mathematical calculations. This Greek abacus saw use in Achaemenid Persia, the Etruscan civilization, Ancient Rome and, until the French Revolution, the Western Christian world. A tablet found on the Greek island Salamis in 1846 AD, dates back to 300 BC, making it the oldest counting board discovered so far.

It is a slab of white marble 149 cm long, 75 cm wide, 4.5 cm thick, on which are 5 groups of markings. In the center of the tablet is a set of 5 parallel lines divided by a vertical line, capped with a semicircle at the intersection of the bottom-most horizontal line and the single vertical line. Below these lines is a wide space with a horizontal crack dividing it. Below this crack is another group of eleven parallel lines, again divided into two sections by a line perpendicular to them, but with the semicircle at the top of the intersection. From this time frame the Darius Vase was unearthed in 1851, it was covered with pictures including a "treasurer" holding a wax tablet in one hand while manipulating counters on a table with the other. The earliest known written documentation of the Chinese abacus dates to the 2nd century BC; the Chinese abacus, known as the suanpan, is 20 cm tall and comes in various widths depending on the operator. It has more than seven rods. There are two beads on each rod in

Mayakovsky Square poetry readings

During the 1950s and 1960s, Mayakovsky Square in Moscow played an important role as a gathering place for unofficial poetry readings, subsequently for expressing cultural and political dissent in the post-Stalin era. On July 29, 1958, a monument to Vladimir Mayakovsky was unveiled in Moscow's Mayakovsky Square. At the official opening ceremony, a number of official Soviet poets read their poems; when the ceremony was over, volunteers from the crowd started reading poetry as well. The atmosphere of free speech attracted many, public readings at the monument soon became regular. Young people students, assembled every evening to read the poems of forgotten or repressed writers; some read their own work, discussed art and literature. Among the young poets who read their own work to huge crowds in Mayakovsky Square were Yevgeny Yevtushenko and Andrei Voznesensky, who walked a thin line between being able to publish in the Soviet Union and representing a spirit of youthful protest, they were tolerated.

The spontaneous gatherings, were soon stopped by the authorities. The gatherings at Mayakovsky's statue were revived in September 1960, again as poetry readings, but this time with a more political character, they were organized by biology student Vladimir Bukovsky with a small circle of university friends, but gathered momentum and were soon taking place regularly. The Square and statue became known to some as "Mayak". Several hundred people gathered each occasion in the square; the participants in the 1960-61 readings included the "veterans" of two years before, as well as a new layer of young people. Poetry by Nikolay Gumilev, Boris Pasternak and Osip Mandelstam was read. Soviet Nonconformist Art and works by formalists were circulated. Among the participants were both those interested in pure art, those inspired by dissident politics of various stripes. Many of those gathering in the square insisted on the right of art to remain "free of politics". Others were drawn to the readings because of their social implications.

This included an oppositionist student movement which had begun to develop out of the shock of Khrushchev's 1956 report on Stalin's purges. For these, like Bukovsky and his colleagues, "the right of art to be independent was one point of opposition to the regime, we were here because art happened to be at the centre of political passions."The circle of students who had organized the Mayakovsky Square began publishing unofficial poetry in the first samizdat journals. They published their own poems but those of Nikolay Zabolotsky, Dmitri Kedrin and Marina Tsvetaeva. Poet and journalist Aleksandr Ginzburg managed to get out three issues of Sintaksis before he was arrested for the first time in 1960. In November 1960, Vladimir Osipov produced one issue of a journal called Bumerang, modeled on Ginzburg's work. A third samizdat journal, Feniks-61, was produced by Yuri Galanskov in 1961. Usual punitive measures for these activities included blacklisting from institutes; the active participants of the gatherings were subject to searches.

Fights were provoked in the square, sometimes the monument was cordoned off during the usual meeting times. The readings at Mayakovsky Square became the incubator not only for a new generation of poets but for a generation of dissidents. Vladimir Osipov, one of the organizers gatherings and a dissident, stated that "it seems it is impossible to find a famous dissident from among the young, who thundered at the end of the sixties and the first half of the seventies, who would hot have appeared at that time on Mayakovsky Square, who did not spend his youth there." On April 14, 1961, the Mayakovsky Square group organized a reading to commemorate the anniversary of Mayakovsky's suicide. The commemoration turned out to be the largest and most eventful gathering in the square, it coincided with a holiday to celebrate Yuri Gagarin's space flight, the square was filled with bystanders, many of whom joined the crowd around Mayakovsky's statue out of curiosity. The meeting was broken up. Many of those involved in the readings were arrested in the summer of 1961.

Vladimir Osipov, Eduard Kuznetsov and Ilya Bokshteyn were soon after convicted under article 70 “anti-Soviet agitation and propaganda” for attempting to create an underground organization. Osipov and Kuznetsov received seven years in labor camps, Bokshetyn five years. Vladimir Bukovsky was interrogated twice in spring 1961, thrown out of university that year. By the autumn of 1961, news of the readings in Mayakovsky Square had begun to filter out to the foreign press, an open campaign began to crush them; the KGB brought snowplows to the Square and circled them around the Mayakovsky statue to prevent the readings from taking place. After a final gathering on the opening day of the 22nd Congress of the Communist Party of the Soviet Union in October of the same year, the readings were banned. In 1965, the gatherings in Mayakovsky Square were revived again by a new youth group called SMOG; the acronym could be deciphered as the Russian words "boldness, thought and depth," or "the youngest society of geniuses".

The SMOGists expressed a trend of 1964-65 toward greater organization among literary dissidents, as compared to the more unstructured and spontaneous readings of the early sixties. For them, concerns for literary freedom were mixed with a political interest in the Russian revolutionary tradition from the Decembrists to Lenin, in other leaders who had opposed Stalin, such as Trotsky and Bukharin. On April 14, 1965, SMOGists organized what they described as a "lit

Benjamín Mendoza y Amor Flores

Benjamín Mendoza y Amor Flores was a Bolivian surrealist painter who made an unsuccessful attempt to assassinate Pope Paul VI in Manila in 1970. Mendoza left La Paz, Bolivia, in 1962. From 1962 until 1970, he lived in Argentina, the United States, Hong Kong and the Philippines. In Argentina, in the early 1960s, he exhibited his work in a few galleries in the San Telmo district and in 1963 illustrated the book Todo estaba sucio, by Raúl Barón Biza, he made two murals for the Manila Hotel in Mar del Plata, which no longer exist. He exhibited in the Soviet Union and after that moved to the Philippines. On November 27, 1970, at 9:30 in the morning, dressed as a priest, crucifix in hand, managed to approach the Pope shortly after the Pontiff disembarked from his chartered DC-8 jet at the Manila International Airport. Mendoza stabbed him twice in the neck with a kris and was deported to Bolivia in 1974. Upon regaining his freedom, Flores organized several exhibitions in more than 80 countries, he lived in Lima.

Asked about his attempt to assassinate Pope Paul VI, he said he wanted to attract attention. According to filmmaker Armando Bó, who made contact with Mendoza, he acted in a "moment of madness". Http://