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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

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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