Abstract
It is well known that a projective module M is ⊕-supplemented if and only if M is semiperfect. We show that a projective module M is ⊕-cofinitely supplemented if and only if M is cofinitely semiperfect or briefly cof-semiperfect (i.e., each finitely generated factor module of M has a projective cover). In this paper we give various properties of the cof-semiperfect modules. If a projective module M is semiperfect then every M-generated module is cof-semiperfect. A ring R is semiperfect if and only if every free R-module is cof-semiperfect.
Similar content being viewed by others
References
Çalışıcı H. and Pancar A., “⊕-cofinitely supplemented modules,” Czech. Math. J., 54, No.129, 1083–1088 (2004).
Wisbauer R., Foundations of Module and Ring Theory, Gordon and Breach, Philadelphia (1991).
Mohamed S. H. and Müller B. J., Continuous and Discrete Modules, Cambridge Univ. Press, Cambridge (1990). (London Math. Soc.; LNS 147.)
Alizade R., Bilhan G., and Smith P. F., “Modules whose maximal submodules have supplements,” Comm. Algebra, 29, No.6, 2389–2405 (2001).
Keskin D., Smith P. F., and Xue W., “Rings whose modules are ⊕-supplemented,” J. Algebra, 218, 470–487 (1999).
Harmancı A., Keskin D., and Smith P. F., “On ⊕-supplemented modules,” Acta Math. Hungar., 83, 161–169 (1999).
Kasch F., Modules and Rings, Acad. Press, London (1982).
Garcia J. L., “Properties of direct summands of modules,” Comm. Algebra, 17, 73–92 (1989).
Lomp C., “On semilocal modules and rings,” Comm. Algebra, 27, 1921–1935 (1999).
Author information
Authors and Affiliations
Additional information
Original Russian Text Copyright © 2005 Çalışıcı H. and Pancar A.
Translated from Sibirski \(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{\imath}\) Matematicheski \(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{\imath}\) Zhurnal, Vol. 46, No. 2, pp. 460–465, March–April, 2005.
Rights and permissions
About this article
Cite this article
Calisici, H., Pancar, A. Cofinitely semiperfect modules. Sib Math J 46, 359–363 (2005). https://doi.org/10.1007/s11202-005-0037-7
Received:
Issue Date:
DOI: https://doi.org/10.1007/s11202-005-0037-7