arXiv 0809.04762008-09math.AC

Goto Numbers of a Numerical Semigroup Ring and the Gorensteiness of Associated Graded Rings

Lance Bryant

备注：: 36 pages, corrected typos and improved exposition throughout. To appear in Communications in Algebra
发表信息：: Comm. Algebra 38 (2010), no. 6, 2092-2128
DOI：: 10.1080/00927870903025993

英文摘要：

The Goto number of a parameter ideal Q in a Noetherian local ring (R,m) is the largest integer q such that Q : m^q is integral over Q. The Goto numbers of the monomial parameter ideals of R = k[[x^{a_1}, x^{a_2},..., x_{a_ν}]] are characterized using the semigroup of R. This helps in computing them for classes of numerical semigroup rings, as well as on a case-by-case basis. The minimal Goto number of R and its connection to other invariants is explored. Necessary and sufficient conditions for the associated graded rings of R and R/x^{a_1}R to be Gorenstein are also given, again using the semigroup of R.

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