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arXiv 2303.08413math.ACmath.RA
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交换环上的矩阵可逆扩张

On matrix invertible extensions over commutative rings

Grigore Calugareanu, Horia F. Pop, Adrian Vasiu

AI总结:

本文定义交换环的 E2 与 SE2 类,刻画幺模 2×2 矩阵扩张为可逆 3×3 矩阵的条件,并给出 Hermite 环成为 EDR 的新判据及相关环类结论。

摘要:

我们引入交换环 R 的类 E2(相应地,SE2),其性质是每个元素在 R 中的幺模 2×2 矩阵都可扩张为一个可逆 3×3 矩阵(相应地,扩张为一个 (3,3) 位置元素为 0 的可逆 3×3 矩阵)。在维数为 1 的诺特整环、Z 或 Hermite 环上的多项式环中,只有 EDR 属于该类。利用这一点、稳定秩以及单位与投射模的解释,我们重新得到(并常常加以改进)Kaplansky、McGovern、Roitman、Shchedryk、Wiegold 等人的判据,并获得 Hermite 环成为 EDR 的新判据。例如,我们通过以下两点刻画作为 EDR 的 Hermite 环:(1) 涉及幺模三元组的方程;(2) 某些涉及主理想商环单位的映射的满射性。我们利用这些判据表明,每个 Bezout 环 R,若其要么是 J2,1 整环,要么是 Lorenzini 引入的 (SU)2 环,并且对每个非零 a∈R,不存在由 2 个元素生成的秩 1 的非平凡自对偶投射 R/Ra-模(例如其所有元素均为平方),则 R 是 EDR,从而解决或部分解决了 Lorenzini 提出的问题。文中还引入并研究了许多其他环类。为便于阅读,本版本仅集中讨论幺模 2×2 矩阵的可扩张性质,因此不考虑 n>2 的情形。

英文摘要:

We introduce the class E2 (resp. SE2) of commutative rings R with the property that each unimodular 2 x 2 matrix with entries in R extends to an invertible 3 x 3 matrix (resp. invertible 3 x 3 matrix whose (3, 3) entry is 0). Among noetherian domains of dimension 1, polynomial rings over Z or Hermite rings, only EDRs belong to the class. Using this, stable ranges, and units and projective modules interpretations, we reobtain (often refine) criteria due to Kaplansky, McGovern, Roitman, Shchedryk, Wiegand and obtain new criteria for a Hermite ring to be an EDR. For instance, we characterize Hermite rings which are EDRs by (1) means of equations involving unimodular triples and (2) surjectivity of some maps involving units of factor rings by principal ideals. We use these criteria to show that each Bezout ring R that is either a J2,1 domain or an (SU)2 ring (as introduced by Lorenzini) such that for each nonzero a 2 R there exists no nontrivial self-dual projective R/Ra-module of rank 1 generated by 2 elements (e.g., all its elements are squares), is an EDR, thus solving or partially solving problems raised by Lorenzini. Many other classes of rings are introduced and studied. To ease the reading, this version concentrates only on extendability properties of unimodular 2 x 2 matrices and hence does not consider the case n > 2.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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