|
In mathematics, an integral domain is a G-domain if and only if: # Its quotient field is a simple extension of # Its quotient field is a finite extension of # Intersection of its nonzero prime ideals (not to be confused with nilradical) is nonzero # There is an element such that for any nonzero ideal , for some .〔Kaplansky, Irving. ''Commutative Algebra''. Polygonal Publishing House, 1974, p. 12,13.〕 A G-ideal is defined as an ideal such that is a G-domain. Since a factor ring is an integral domain if and only if the ring is factored by a prime ideal, every G-ideal is also a prime ideal. G-ideals can be used as a refined collection of prime ideals in the following sense: Radical can be characterized as the intersection of all prime ideals containing the ideal, and in fact we still get the radical even if we take the intersection over the G-ideals.〔Kaplansky, Irving. ''Commutative Algebra''. Polygonal Publishing House, 1974, p. 16,17.〕 Every maximal ideal is a G-ideal, since quotient by maximal ideal is a field, and a field is trivially a G-domain. Therefore, maximal ideals are G-ideals, and G-ideals are prime ideals. G-ideals are the only maximal ideals in Jacobson ring, and in fact this is an equivalent characterization of a Jacobson ring: a ring is a Jacobson ring when all maximal ideals are G-ideals. This leads to a simplified proof of the Nullstellensatz.〔Kaplansky, Irving. ''Commutative Algebra''. Polygonal Publishing House, 1974, p. 19.〕 It is known that given , a ring extension of a G-domain, is algebraic over if and only if every ring extension between and is a G-domain.〔Dobbs, David. "G-Domain Pairs". Trends in Commutative Algebra Research, Nova Science Publishers, 2003, p. 71-75.〕 A Noetherian domain is a G-domain iff its rank is at most one, and has only finitely many maximal ideals (or equivalently, prime ideals).〔Kaplansky, Irving. "Commutative Algebra''. Polygonal Publishing House, 1974, p. 19.〕 ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「G-domain」の詳細全文を読む スポンサード リンク
|