Wheels are a kind of algebra where division is always defined. In particular, division by zero is meaningful. The real numbers can be extended to a wheel, as can any commutative ring. Also the Riemann sphere can be extended to a wheel by adjoining an element 0/0. The Riemann sphere is an extension of the complex plane by an element \infty, where z/0=\infty for any complex z\neq 0. However, 0/0 is still undefined on the Riemann sphere, but defined in wheels. The algebra of wheels Wheels discard the usual notion of division being a binary operator, replacing it with multiplication by a...

The Master and Margarita () is a novel by Mikhail Bulgakov, written between 1928 and 1940 but unpublished in book form until 1967. It is woven around a visit by the Devil to the fervently atheistic Soviet Union. Many critics consider it to be one of the best novels of the 20th century, and the foremost of Soviet satires. In part, it is angled against a suffocatingly bureaucratic social order. History Bulgakov started writing the novel in 1928. He burned the first manuscript of the novel in 1930, seeing no future as a writer in the Soviet Union. The work was restarted in 1931. In 1935 B...

In ancient Greece, hetairai (singular , plural ; in Greek ) or hetaerae were courtesans—highly educated, sophisticated companions. Although most engaged in sexual relations with their patrons, hetairai were not simple prostitutes. Overview In ancient Greek society, hetairai were independent and sometimes influential women who were required to wear distinctive dresses and had to pay taxes. Mostly ex-slaves from other cities, these courtesans were renowned for their achievements in dance and music, as well as for their physical and intellectual talents. Unlike most other women in Greek s...