Abstract
We investigate the so-called order-sobrification monad proposed by Ho et al. (Log Methods Comput Sci 14:1–19, 2018) for solving the Ho–Zhao problem, and show that this monad is commutative. We also show that the Eilenberg–Moore algebras of the order-sobrification monad over dcpo’s are precisely the strongly complete dcpo’s and the algebra homomorphisms are those Scott-continuous functions preserving suprema of irreducible subsets. As a corollary, we show that this monad gives rise to the free strongly complete dcpo construction over the category of posets and Scott-continuous functions. A question related to this monad is left open alongside our discussion, an affirmative answer to which might lead to a uniform way of constructing non-sober complete lattices.

Similar content being viewed by others
References
Escardó, M.: Properly injective spaces and function spaces. Topol. Appl. 89, 75–120 (1998)
Gierz, G., Hofmann, K.H., Keimel, K., Lawson, J.D., Mislove, M., Scott, D.S.: Continuous Lattices and Domains, Volume 93 of Encyclopedia of Mathematics and its Applications. Cambridge University Press, Cambridge (2003)
Goubault-Larrecq, J.: Non-Hausdorff Topology and Domain Theory, Volume 22 of New Mathematical Monographs. Cambridge University Press, Cambridge (2013)
Ho, W.K., Goubault-Larrecq, J., Jung, A., Xi, X.: The Ho–Zhao problem. Log. Methods Comput. Sci. 14, 1–19 (2018)
Johnstone, P.T.: Scott is not always sober. In: Banaschewski, B., Hoffmann, R.-E. (eds.) Continuous Lattices, Proceedings Bremen 1979, Volume 871 of Lecture Notes in Mathematics, pp. 282–283. Springer, Berlin (1981)
Jung, A.: Cartesian Closed Categories of Domains, Volume 66 of CWI Tracts. Centrum voor Wiskunde en Informatica, Amsterdam (1989)
Mac Lane, S.: Categories for the Working Mathematician, Volume 5 of Graduate Texts in Mathematics. Springer, Berlin (1971)
Moggi, E.: Notions of computations and monads. Inf. Comput. 93(1), 55–92 (1991)
Schalk, A.: Algebras for generalized power constructions. Doctoral thesis, Technische Hochschule Darmstadt (1993)
Zhao, D., Fan, T.: Dcpo-completion of posets. Theor. Comput. Sci. 411, 2167–2173 (2010)
Acknowledgements
I would like to thank the anonymous referees for their careful reading of our submission and for the many helpful comments and suggestions which improve the paper greatly.
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by Martín Escardó.
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
This research was partially supported by Labex DigiCosme (Project ANR-11-LABEX-0045-DIGICOSME) operated by ANR as part of the program “Investissement d’Avenir” Idex Paris-Saclay (ANR-11-IDEX-0003-02).
Rights and permissions
About this article
Cite this article
Jia, X. The Order-Sobrification Monad. Appl Categor Struct 28, 845–852 (2020). https://doi.org/10.1007/s10485-020-09599-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10485-020-09599-6