Pełnotekstowe zasoby PLDML oraz innych baz dziedzinowych są już dostępne w nowej Bibliotece Nauki.
Zapraszamy na https://bibliotekanauki.pl
Zapraszamy na https://bibliotekanauki.pl
Czasopismo
Tytuł artykułu
Treść / Zawartość
Pełne teksty:
![https://www.impan.pl/download/pdf/fm217-3-2 [zdalny]](images/mime-icons/pdf.gif "fm217-3-2.pdf")
Warianty tytułu
Języki publikacji
Abstrakty
In this paper we improve recent results dealing with cellular covers of R-modules. Cellular covers (sometimes called colocalizations) come up in the context of homotopical localization of topological spaces. They are related to idempotent cotriples, idempotent comonads or coreflectors in category theory.
Recall that a homomorphism of R-modules π: G → H is called a cellular cover over H if π induces an isomorphism $π⁎: Hom_{R}(G,G) ≅ Hom_{R}(G,H)$, where π⁎(φ) = πφ for each $φ ∈ Hom_{R}(G,G)$ (where maps are acting on the left). On the one hand, we show that every cotorsion-free R-module of rank $κ < 2^{ℵ₀}$ is realizable as the kernel of some cellular cover G → H where the rank of G is 3κ + 1 (or 3, if κ = 1). The proof is based on Corner's classical idea of how to construct torsion-free abelian groups with prescribed countable endomorphism rings. This complements results by Buckner-Dugas. On the other hand, we prove that every cotorsion-free R-module H that satisfies some rigid conditions admits arbitrarily large cellular covers G → H. This improves results by Fuchs-Göbel and Farjoun-Göbel-Segev-Shelah.
Recall that a homomorphism of R-modules π: G → H is called a cellular cover over H if π induces an isomorphism $π⁎: Hom_{R}(G,G) ≅ Hom_{R}(G,H)$, where π⁎(φ) = πφ for each $φ ∈ Hom_{R}(G,G)$ (where maps are acting on the left). On the one hand, we show that every cotorsion-free R-module of rank $κ < 2^{ℵ₀}$ is realizable as the kernel of some cellular cover G → H where the rank of G is 3κ + 1 (or 3, if κ = 1). The proof is based on Corner's classical idea of how to construct torsion-free abelian groups with prescribed countable endomorphism rings. This complements results by Buckner-Dugas. On the other hand, we prove that every cotorsion-free R-module H that satisfies some rigid conditions admits arbitrarily large cellular covers G → H. This improves results by Fuchs-Göbel and Farjoun-Göbel-Segev-Shelah.
Słowa kluczowe
Kategorie tematyczne
Czasopismo
Rocznik
Tom
Numer
Strony
211-231
Opis fizyczny
Daty
wydano
2012
Twórcy
autor
- Department of Mathematics, University of Duisburg-Essen, Campus Essen, 45117 Essen, Germany
autor
- Área de Geometría y Topología, Facultad de Ciencias Experimentales, University of Almería, La cañada de San Urbano, 04120 Almería, Spain
autor
- Department of Mathematics, University of Duisburg-Essen, Campus Essen, 45117 Essen, Germany
Bibliografia
Typ dokumentu
Bibliografia
Identyfikatory
Identyfikator YADDA
bwmeta1.element.bwnjournal-article-doi-10_4064-fm217-3-2
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.