Artinian rings characterized by direct sums of CS modules


Er N. F.

COMMUNICATIONS IN ALGEBRA, cilt.32, sa.12, ss.4821-4833, 2004 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 32 Konu: 12
  • Basım Tarihi: 2004
  • Doi Numarası: 10.1081/agb-200039290
  • Dergi Adı: COMMUNICATIONS IN ALGEBRA
  • Sayfa Sayıları: ss.4821-4833

Özet

In this note, we show that the following are equivalent for a ring R for which the socle or the injective hull of R-R is finitely generated: (i) The direct sum of any two CS right R-modules is again CS; (ii) R is right Artinian and every uniform right R-module has composition length at most two. Next we give partial answers to a question of Huynh whether a right countably Sigma-CS ring which either is semilocal or has finite Goldie dimension is right Sigma-CS. We give characterizations, in terms of radicals, of when such rings are right Sigma-CS. In particular, for the semilocal case, Huynh's question is reduced to whether rad(Z(2)(R-R)) is Sigma-CS or Noetherian, where Z(2)(R-R) is the second singular right ideal of R. Our results yield new characterizations of QF-rings.