Serial rings with right Krull dimension one, II
Serial rings with right Krull dimension one, II
复制标题
右克鲁尔尺寸一、二系列环
DOI:
10.1016/0021-8693(88)90243-8
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发表时间:
1988
影响因子:
0.9
通讯作者:
M. H. Wright
中科院分区:
文献类型:
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作者:
M. H. Wright
A module is uniserial if its submodules are linearly ordered under inclusion. A ring is right serial if it is a direct sum of uniserial right ideals. No chain conditions are assumed. A right serial ring is necessarily semiperfeet. The structure of a nonsingular (left and right) serial ring with right Krull dimension one was described in [12]. In this paper, we describe the structure of an arbitrary serial ring of right Krull dimension one. We also give an example to show that a uniform module over a serial ring of Krull dimension one need not be uniserial. Thus a fact which was very useful in the study of Noetherian serial rings and nonsingular serial rings of Krull dimension one [12, 131 is no longer available. We shall show that the local projective modules over a serial ring of Krull dimension one are naturally organized into “cliques”(see definitions below). These give rise to elementary serial rings: serial rings which have only one clique. An elementary serial ring falls into one of four categories, depending on characteristics of the clique from which it arises. This is the subject matter of Section 1. In Section 2 we describe the structure of an arbitrary serial ring of Krull dimension one in terms of the elementary rings arising from its cliques. A local module is one with unique maximal proper submodule. A local element is one which generates a local module. For details on Krull dimension and critical modules, see [6]. A ring is QF if it is Artinian and an injective cogenerator on both sides. R is right PF if R is injective as a right R-module and semiperfect with fg essential right socle. R is right QF-3 if there is a minimal faithful module (in the sense that it is a direct summand of every faithful module). Z (M) denotes the singular submodule of the module M. Given simple right R-modules U and V, U is called a (k-th degree) successor of V (and V a k-th degree predecessor of U) if there exists a uniserial module M such that M/MJz V and MJk EU [131. The (first degree) successor of V, when it exists, is denoted by U= a (V). 99
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