We show that a direct limit of projective contramodules (over a right linear topological ring) is projective if it has a projective cover. A similar result is obtained for ∞-strictly flat contramodules of projective dimension not exceeding 1, using an argument based on the notion of the topological Jacobson radical. Covers and precovers of direct limits of more general classes of objects, both in abelian categories with exact and with nonexact direct limits, are also discussed, with an eye towards the Enochs conjecture about covers and direct limits, using locally split (mono)morphisms as the main technique. In particular, we offer a simple elementary proof of the Enochs conjecture for the left class of an n-tilting cotorsion pair in an abelian category with exact direct limits.

Projective covers of flat contramodules

Bazzoni Silvana
;
2022

Abstract

We show that a direct limit of projective contramodules (over a right linear topological ring) is projective if it has a projective cover. A similar result is obtained for ∞-strictly flat contramodules of projective dimension not exceeding 1, using an argument based on the notion of the topological Jacobson radical. Covers and precovers of direct limits of more general classes of objects, both in abelian categories with exact and with nonexact direct limits, are also discussed, with an eye towards the Enochs conjecture about covers and direct limits, using locally split (mono)morphisms as the main technique. In particular, we offer a simple elementary proof of the Enochs conjecture for the left class of an n-tilting cotorsion pair in an abelian category with exact direct limits.
File in questo prodotto:
File Dimensione Formato  
cover-direct_v12 copy.pdf

accesso aperto

Descrizione: Articolo principale
Tipologia: Preprint (AM - Author's Manuscript - submitted)
Licenza: Accesso gratuito
Dimensione 514.39 kB
Formato Adobe PDF
514.39 kB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3399825
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 13
  • ???jsp.display-item.citation.isi??? 13
  • OpenAlex ND
social impact