Russian ruble against the U.S. dollar. A 6.5 percentage point interest rate rise to 17 percent failed to prevent the currency hitting record lows in a "perfect storm" of low oil prices, looming recession and Western sanctions over the Ukraine crisis. Russian ruble The Russian ruble or rouble ( "rublʹ", plural: "rubli"; sign: ₽, руб; code: RUB) is the currency of the Russian Federation, the two partially recognised republics of Abkhazia and South Ossetia and the two unrecognised republics of Donetsk and Luhansk. The ruble is subdivided into 100 "kopeks" (sometimes written as "kopecks" or "copecks"; "kopeyka", plural: "kopeyki"). The ruble was
Divided power structure Divided power structure In mathematics, specifically commutative algebra, a divided power structure is a way of making expressions of the form formula_1 meaningful even when it is not possible to actually divide by formula_2. Let "A" be a commutative ring with an ideal "I". A divided power structure (or PD-structure, after the French "puissances divisées") on "I" is a collection of maps formula_3 for "n" = 0, 1, 2, ... such that: For convenience of notation, formula_18 is often written as formula_19 when it is clear what divided power structure is meant. The term "divided power ideal" refers to an