nijednostka
Nijednostka is a term used in some Slavic-language mathematical texts to denote a non-unit element of a ring with identity. A unit is an element that has a multiplicative inverse; therefore a nijednostka is an element without such an inverse. In English-language literature the standard term is non-unit. The concept is fundamental in ring theory and in the study of how elements interact under multiplication.
Examples help illustrate the idea. In the ring of integers Z, the only units are 1 and
Relations and properties. The set of nijednostki is not generally an ideal, but in a local ring
See also: units, ring theory, maximal ideal, local ring, Jacobson radical, ideals. The term nijednostka reflects