Locally Realized Covering Relation
المؤلف:
Burris, S. and Sankappanavar, H. P
المصدر:
A Course in Universal Algebra. New York: Springer-Verlag, 1981. http://www.thoralf.uwaterloo.ca/htdocs/ualg.html.
الجزء والصفحة:
...
2-1-2022
2392
Locally Realized Covering Relation
Let
be a lattice (or a bounded lattice or a complemented lattice, etc.), and let
be the covering relation of
:
{(x,y) in L^2|x covers y or y covers x}. " src="https://mathworld.wolfram.com/images/equations/LocallyRealizedCoveringRelation/NumberedEquation1.gif" style="height:21px; width:247px" /> |
Then
is locally realized provided that for every finite subset
of
, there is a finitely generated sublattice
of
, that contains
, for which
. It can be shown that
is locally realized if and only if there is a hyperfinitely generated sublattice
of
such that
. Using this characterization of locally realized covering relations, the following standard result can be proved using nonstandard methods:
Let
be a locally finite lattice in which the covering relation is locally realized, and let
be the sublattice of
which is generated by
. Then
is a connected tolerance of
, and it is in fact the smallest locally subconnected (and locally connected) tolerance of
.
REFERENCES:
Burris, S. and Sankappanavar, H. P. A Course in Universal Algebra. New York: Springer-Verlag, 1981. http://www.thoralf.uwaterloo.ca/htdocs/ualg.html.
Gehrke, M.; Kaiser, K.; and Insall, M. "Some Nonstandard Methods Applied to Distributive Lattices." Zeitschrifte für Mathematische Logik und Grundlagen der Mathematik 36, 123-131, 1990.
Grätzer, G. Lattice Theory: First Concepts and Distributive Lattices. San Francisco, CA: W. H. Freeman, 1971.
Grätzer, G. Universal Algebra, 2nd ed. New York: Springer-Verlag, 1979.
Insall, M. "Some Finiteness Conditions in Lattices Using Nonstandard Proof Methods." J. Austral. Math. Soc. 53, 266-280, 1992.
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