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7 - FGF Rings

Published online by Cambridge University Press:  14 September 2009

W. K. Nicholson
Affiliation:
University of Calgary
M. F. Yousif
Affiliation:
Ohio State University
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Summary

A theorem of Faith and Walker asserts that a ring R is quasi-Frobenius if and only if every injective right R-module is projective and hence that every right module over a quasi-Frobenius ring embeds in a free module. There is an open problem here. If we call a ring R a right FGF ring if every finitely generated right R-module can be embedded in a free right R-module, it is not known if the following assertion is true:

The FGF-Conjecture. Every right FGF ring is quasi-Frobenius

Here are four important results on the conjecture:

  1. Every left Kasch, right FGF ring is quasi-Frobenius.

  2. Every right self-injective, right FGF ring is quasi-Frobenius.

  3. Every right perfect, right FGF ring is quasi-Frobenius.

  4. Every right CS, right FGF ring is quasi-Frobenius.

We prove all these assertions; in fact we capture all of (1), (2), and (3) in Theorem 7.19: If Mn(R) is a right C2 ring for each n ≥ 1 and every 2-generated right R-module embeds in a free module then R is quasi-Frobenius. This theorem also implies that the FGF-conjecture is true for right FP-injective rings, and it reformulates the conjecture by showing that it suffices to prove that every right FGF ring is a right C2 ring. Furthermore, the theorem shows that the conjecture is true for semiregular rings with Zr = J. We call these rings right weakly continuous, and investigate their basic properties.

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Quasi-Frobenius Rings , pp. 164 - 200
Publisher: Cambridge University Press
Print publication year: 2003

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  • FGF Rings
  • W. K. Nicholson, University of Calgary, M. F. Yousif, Ohio State University
  • Book: Quasi-Frobenius Rings
  • Online publication: 14 September 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511546525.008
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  • FGF Rings
  • W. K. Nicholson, University of Calgary, M. F. Yousif, Ohio State University
  • Book: Quasi-Frobenius Rings
  • Online publication: 14 September 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511546525.008
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • FGF Rings
  • W. K. Nicholson, University of Calgary, M. F. Yousif, Ohio State University
  • Book: Quasi-Frobenius Rings
  • Online publication: 14 September 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511546525.008
Available formats
×