Sifted colimits, strongly finitary monads and continuous algebras

Jiří Adámek, Matěj Dostál, and Jiří Velebil

We characterize strongly finitary monads on categories Pos, CPO and DCPO as precisely those preserving sifted colimits. Or, equivalently, enriched finitary monads preserving reflexive coinserters. We study sifted colimits in general enriched categories. For CPO and DCPO we characterize varieties of continuous algebras as precisely the monadic categories for strongly finitary monads.

Keywords: sifted colimit, monad, continuous algebra

2020 MSC: 18C15

Theory and Applications of Categories, Vol. 44, 2025, No. 3, pp 84-131.

Published 2025-01-14.

http://www.tac.mta.ca/tac/volumes/44/3/44-03.pdf

TAC Home