Notes on commutation of limits and colimits

Marie Bjerrum, Peter Johnstone, Tom Leinster, William F. Sawin

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


We show that there are infinitely many distinct closed classes of colimits (in the sense of the Galois connection induced by commutation of limits and colimits in Set) which are intermediate between the class of pseudo-filtered colimits and that of all (small) colimits. On the other hand, if the corresponding class of limits contains either pullbacks or equalizers, then the class of colimits is contained in that of pseudo-filtered colimits.

Original languageEnglish (US)
Pages (from-to)527-532
Number of pages6
JournalTheory and Applications of Categories
StatePublished - Apr 30 2015

All Science Journal Classification (ASJC) codes

  • Mathematics (miscellaneous)


  • Colimit
  • Fitered colimit
  • Galois connection
  • Group action
  • Limit
  • Simple group


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