It is shown that the descent constructions of รฟnite preorders provide a simple motivation for those of topological spaces, and new counter-examples to open problems in Topological descent theory are constructed.
Self complementary topologies and preorders
โ Scribed by Jason I. Brown; Stephen Watson
- Publisher
- Springer Netherlands
- Year
- 1991
- Tongue
- English
- Weight
- 709 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0167-8094
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โฆ Synopsis
A topology on a set X is self complementary if there is a homeomorphic copy on the same set that is a complement in the lattice of topologies on X. The problem of characterizing finite self complementary topologies leads us to redefine the problem in terms of preorders (i.e. reflexive, transitive relations). A preorder P on a set X is self complementary if there is an isomorphic copy P' of P on X that is arc disjoint to P (except for loops) and with the property that P v P' is strongly connected. We characterize here self complementary finite partial orders and self complementary finite equivalence relations.
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