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A Classification of Hull Operators in Archimedean Lattice-Ordered Groups With Unit
Categories and General Algebraic Structures with Applications
  • Ricardo Enrique Carrera, Nova Southeastern University
  • Anthony W. Hager, Wesleyan University
Document Type
Article
Publication Date
7-1-2020
Keywords
  • Lattice-ordered group,
  • Archimedean,
  • Weak unit,
  • Bounded monocoreflection,
  • Essential extension,
  • Hull operator,
  • Partially ordered semigroup
Abstract

The category, or class of algebras, in the title is denoted by W. A hull operator (ho) in W is a reflection in the category consisting of W objects with only essential embeddings as morphisms. The proper class of all of these is hoW. The bounded monocoreflection in W is denoted B. We classify the ho’s by their interaction with B as follows. A “word” is a function w : hoWWW obtained as a finite composition of B and x a variable ranging in hoW. The set of these,“Word”, is in a natural way a partially ordered semigroup of size 6, order isomorphic to F(2), the free 0 −1 distributive lattice on 2 generators. Then, hoW is partitioned into 6 disjoint pieces, by equations and inequations in words, and each piece is represented by a characteristic order-preserving quotient of Word (≈ F(2)). Of the 6: 1 is of size ≥ 2, 1 is at least infinite, 2 are each proper classes, and of these 4, all quotients are chains; another 1 is a proper class with unknown quotients; the remaining 1 is not known to be nonempty and its quotients would not be chains.

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Citation Information
Ricardo Enrique Carrera and Anthony W. Hager. "A Classification of Hull Operators in Archimedean Lattice-Ordered Groups With Unit" Categories and General Algebraic Structures with Applications Vol. 13 Iss. 1 (2020) p. 83 - 103 ISSN: 2345-5853
Available at: http://works.bepress.com/ricardo-carrera/28/