Analogously to the fact that Lawvere's algebraic theories of finitary varieties Ε½ . are precisely the small categories with finite products, we prove that i algebraic theories of many-sorted quasivarieties are precisely the small, left exact categories Ε½ . with enough regular injectives and ii algeb
Algebraic theories of compact pospaces
β Scribed by Bob Flagg
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 819 KB
- Volume
- 77
- Category
- Article
- ISSN
- 0166-8641
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β¦ Synopsis
Let CmptPoSp denote the category of compact pospaces with continuous monotone maps and let PoSet denote the category of partially ordered sets and monotone maps. In this paper we show that the forgetful functor G : CmptPoSp + PoSet is monadic; that is, G has a left-adjoint and CmptPoSp is isomorphic to the category of algebras PoSetB for the monad B on PoSet induced by the adjunction. This result, which is an asymmetric version of Manes' theorem, shows that the notion of compact pospace is algebraic in a precise sense and provides a useful tool for investigating the category CmptPoSp. As a corollary we obtain the theorem of Simmons and Wyler which says that CmptPoSp is also algebraic over the category of topological spaces and continuous maps.
This makes explicit the connection between the Salbany and the prime Wallman compactifications. We also give an explicit construction-as the prime spectrum of the lattice of upper sets+f the Stone-Tech-Nachbin order compactification for a discrete ordered space.
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