Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-24T09:32:44.040Z Has data issue: false hasContentIssue false

Direct summands in l-groups

Published online by Cambridge University Press:  14 November 2011

John Boris Miller
Affiliation:
Department of Mathematics, Monash University, Victoria, Australia

Synopsis

We discuss convex l-subgroups of an l-group G in their role as direct summands, not so much of G as of each other. This is done by writing AdB for subgroups A, B to mean that A is a direct summand of B, and studying the properties of the resulting poset. It is shown to be a hypolattice, that is, to have local lattice properties in a certain sense. However it need not be a lattice; and there may exist meets of pairs of elements, outside the hypolattice structure. It need not be conditionally complete even when G is conditionally complete. We look also at the map which sends a subgroup to its lattice-closure; the lattice-closed subgroups also form a hypolattice. Our main result asserts that this hypolattice is conditionally complete if G is. The paper ends with some examples and counter examples in C(X).

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1978

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1Byrd, R. D. and Lloyd, J. T.Closed subgroups and complete distributivity in lattice-ordered groups. Math. Z. 101 (1967), 123130.CrossRefGoogle Scholar
2Conrad, P.The lattice of all convex L-subgroups of a lattice-ordered group. Czechoslovak Math. J. 15 (1965), 101122.CrossRefGoogle Scholar
3Conrad, P. Lattice ordered groups. Tulane Univ. Lecture Notes (1970).CrossRefGoogle Scholar
4Fuchs, L.Partially ordered algebraic systems (Oxford: Pergamon, 1963).Google Scholar
5Fuchs, L.Infinite abelian groups, I (New York: Academic Press, 1970).Google Scholar
6Nachbin, L.Sur les espaces topologiques ordonnés, C.R. Acad. Sci. Paris 226 (1948), 381382. See also Topology and order, Van Nostrand Math. Studies, 4 (1965), 101.Google Scholar
7Riesz, F.Sur quelques notions fondamentales dans la théorie générale des operations linéaires. Annals Math. 41 (1940), 174206.CrossRefGoogle Scholar