Abstract
Ultrafilter extensions of arbitrary first-order models were introduced in Saveliev (2012). The main precursor of this construction was the extension of semigroups to semigroups of ultrafilters, a technique that was used to obtain significant results in algebra and dynamics. Here we consider another particular case where the models are linearly ordered sets. We explicitly calculate the extensions of a given linear order and the corresponding operations of minimum and maximum on a set. We show that the extended relation is no longer an order though it is close to the natural linear ordering of nonempty half-cuts of the set and that the two extended operations define a skew lattice structure on the set of ultrafilters.
Similar content being viewed by others
References
Bezhanishvili, G., Morandi, P.J.: Order-compactifications of totally ordered spaces: revisited. Order 28(3), 577–592 (2011)
Biryukov, A.P.: Varieties of idempotent semigroups. Algebra i Logika 9(3), 255–273 (1970) (Russ. Engl. Transl. Algebra Logic 9(3), 153–164 (1970))
Comfort, W.W., Negrepontis, S.: The Theory of Ultrafilters. Springer, Berlin (1974)
Fedorchuk, V.V.: On ordered spaces. Dokl. Akad. Nauk SSSR Ser. Mat. 169(1), 777–780 (1966) (Russ. Engl. Transl. Soviet Math. Dokl. 7, 1011–1014 (1966))
Fedorchuk, V.V.: Some problems in the theory of ordered sets. Sibirskii Mat. J. 10(1), 172–187 (1969) (Russ. Engl. Transl. Sibirean Math. J. 10(1), 124–132 (1969))
Fennemore, Ch.: All varieties of bands. Semigroup Forum 1(1), 172–179 (1970)
Gerhard, J.A.: The lattice of equational classes of idempotent semigroups. J. Algebra 15(2), 195–224 (1970)
Hindman, N., Strauss, D.: Algebra in the Stone–Čech Compactification. 2nd edn, revised and expanded. Walter de Gruyter, Berlin (2012)
Jordan, P.: Über nichtkommutative Verbände. Arch. Math. 2, 56–59 (1949)
Kaufman, R.: Ordered sets and compact spaces. Colloq. Math. 17, 35–39 (1967)
Kepka, T.: Quasitrivial groupoids and balanced identities. Acta Univ. Carol. Math. Phys. 22(2), 49–64 (1981)
Leech, J.E.: Skew lattices in rings. Algebra Univers. 27, 48–72 (1989)
Leech, J.E.: Recent developments in the theory of skew lattices. Semigroup Forum 52, 7–24 (1996)
Nagy, A.: Special Classes of Semigroups. Kluwer, Dordrecht (2001)
Rosenstein, J.G.: Linear Orderings. Academic, New York (1982)
Saveliev, D.I.: Ultrafilter extensions of models. Lecture Notes in AICS, Springer, vol. 6521, pp. 162–177 (2011). An extended version in: Friedman, S.-D. et al. (eds.) The Infinity Project Proceedings. CRM Documents 11, Barcelona, pp. 599–616 (2012)
Saveliev, D.I.: Formulas stable under ultrafilter extensions of models. In progress
Author information
Authors and Affiliations
Corresponding author
Additional information
Partially supported by RFBR grants 11-01-00958 and 11-01-93107 and ARRS grant P1-0288. Avalaible at arXiv:1310.4533 [math.LO].
Rights and permissions
About this article
Cite this article
Saveliev, D. Ultrafilter Extensions of Linearly Ordered Sets. Order 32, 29–41 (2015). https://doi.org/10.1007/s11083-013-9313-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11083-013-9313-5