Mathematics / Matematik

Permanent URI for this collectionhttps://hdl.handle.net/11147/8

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  • Article
    Citation - WoS: 28
    Citation - Scopus: 29
    Rad-Supplemented Modules
    (Universita di Padova, 2010) Büyükaşık, Engin; Mermut, Engin; Özdemir, Salahattin
    Let τ be a radical for the category of left R-modules for a ring R. If M is a τ-coatomic module, that is, if M has no nonzero τ-torsion factor module, then τ(M) is small in M. If V is a τ-supplement in M, then the intersection of V and τ(M) is τ(V). In particular, if V is a Rad-supplement in M, then the intersection of V and Rad(M) is Rad(V). A module M is τ-supplemented if and only if the factor module of M by P τ(M) is τ-supplemented where P τ(M) is the sum of all τ-torsion submodules of M. Every left R-module is Rad-supplemented if and only if the direct sum of countably many copies of R is a Rad-supplemented left R-module if and only if every reduced left R-module is supplemented if and only if R/P(R) is left perfect where P(R) is the sum of all left ideals I of R such that Rad I = I. For a left duo ring R, R is a Rad-supplemented left R-module if and only if R/P(R) is semiperfect. For a Dedekind domain R, an R-module M is Rad-supplemented if and only if M/D is supplemented where D is the divisible part of M.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 11
    Extensions of Weakly Supplemented Modules
    (Mathematica Scandinavica, 2008) Alizade, Rafail; Büyükaşık, Engin
    It is shown that weakly supplemented modules need not be closed under extension (i.e. if U and M/U are weakly supplemented then M need not be weakly supplemented). We prove that, if U has a weak supplement in M then M is weakly supplemented. For a commutative ring R, we prove that R is semilocal if and only if every direct product of simple R-modules is weakly supplemented.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 14
    Rings Whose Modules Are Weakly Supplemented Are Perfect. Applications To Certain Ring Extensions
    (Mathematica Scandinavica, 2009) Büyükaşık, Engin; Lomp, Christian
    In this note we show that a ring R is left perfect if and only if every left R-module is weakly supplemented if and only if R is semilocal and the radical of the countably infinite free left R-module has a weak supplement.