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On E k -rings

Alessandra Cherubini, Ada Varisco (1988)

Czechoslovak Mathematical Journal

On filial rings

Andrusziewicz, R., Puczylowski, E.R. (1988)

Portugaliae mathematica

On FI-mono-retractable modules

Marziyeh Atashkar, Yahya Talebi (2022)

Commentationes Mathematicae Universitatis Carolinae

We introduce the notion of FI-mono-retractable modules which is a generalization of compressible modules. We investigate the properties of such modules. It is shown that the rings over which every cyclic module is FI-mono-retractable are simple Noetherian V -ring with zero socle or Artinian semisimple. The last section of the paper is devoted to the endomorphism rings of FI-retractable modules.

On flat covers in varieties

David Kruml (2008)

Commentationes Mathematicae Universitatis Carolinae

Flat covers do not exist in all varieties. We give a necessary condition for the existence of flat covers and some examples of varieties where not all algebras have flat covers.

On generalization of injectivity

Roger Yue Chi Ming (1992)

Archivum Mathematicum

Characterizations of quasi-continuous modules and continuous modules are given. A non-trivial generalization of injectivity (distinct from p -injectivity) is considered.

On generalized CS-modules

Qingyi Zeng (2015)

Czechoslovak Mathematical Journal

An 𝒮 -closed submodule of a module M is a submodule N for which M / N is nonsingular. A module M is called a generalized CS-module (or briefly, GCS-module) if any 𝒮 -closed submodule N of M is a direct summand of M . Any homomorphic image of a GCS-module is also a GCS-module. Any direct sum of a singular (uniform) module and a semi-simple module is a GCS-module. All nonsingular right R -modules are projective if and only if all right R -modules are GCS-modules.

On generalized q.f.d. modules

Mohammad Saleh, S. K. Jain, Sergio R. López-Permouth (2005)

Archivum Mathematicum

A right R -module M is called a generalized q.f.d. module if every M-singular quotient has finitely generated socle. In this note we give several characterizations to this class of modules by means of weak injectivity, tightness, and weak tightness that generalizes the results in [sanh1], Theorem 3. In particular, it is shown that a module M is g.q.f.d. iff every direct sum of M -singular M -injective modules in σ [ M ] is weakly injective iff every direct sum of M -singular weakly tight is weakly tight iff...

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