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Creators/Authors contains: "Harding, John"

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  1. We show that the variety of monadic ortholattices is closed under MacNeille and canonical completions. In each case, the completion of L is obtained by forming an associated dual space X that is a monadic orthoframe. This is a set with an orthogonality relation and an additional binary relation satisfying certain conditions. For the MacNeille completion, X is formed from the non-zero elements of L, and for the canonical completion, X is formed from the proper filters of L. The corresponding completion of L is then obtained as the ortholattice of bi-orthogonally closed subsets of X with an additional operation defined through the binary relation of X. With the introduction of a suitable topology on an orthoframe, as was done by Goldblatt and Bimb´o, we obtain a dual adjunction between the categories of monadic ortholattices and monadic orthospaces. A restriction of this dual adjunction provides a dual equivalence. 
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    Free, publicly-accessible full text available May 1, 2026
  2. Abstract An irreducible complete atomicomlof infinite height cannot be algebraic and have the covering property. However, modest departure from these conditions allows infinite-height examples. We use an extension of Kalmbach’s construction to the setting of infinite chains to provide an example of an infinite-height, irreducible, algebraicomlwith the 2-covering property, and Keller’s construction provides an example of an infinite-height, irreducible, completeomlthat has the covering property and is completely hereditarily atomic. Completely hereditarily atomicomlsgeneralize algebraicomls suitably to quantum predicate logic. 
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