The third cohomology group classifies double central extensions

Diana Rodelo, Tim Van Der Linden

Research output: Contribution to specialist/vulgarizing publicationArticleSpecialist


We characterise the double central extensions in a semi-abelian category in terms of commutator conditions. We prove that the third cohomology group H^3(Z, A) of an object Z with coefficients in an abelian object A classifies the double central extensions of Z by A.
Original languageEnglish
Number of pages22
Specialist publicationPré-Publicações DMUC
Publication statusPublished - 28 Nov 2008


  • cohomology
  • categorical Galois theory
  • semi-abelian category
  • higher central extension
  • Baer sum


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