Ring of integers
(重定向自Integer ring)
In mathematics, the ring of integers of an algebraic number field K is the ring of all integral elements contained in K. An integral element is a root of a monic polynomial with rational integer coefficients, x + cn−1x + … + c0 . This ring is often denoted by OK or . Since any rational integer number belongs to K and is its integral element, the ring Z is always a subring of OK.