Definability properties and the congruence closure |
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Authors: | Xavier Caicedo |
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Institution: | (1) Departamento de Matemáticas, Universidad Nacional de Colombia, Apartado aéreo 2509, Bogota, Colombia |
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Abstract: | We introduce a natural class of quantifiersTh containing all monadic type quantifiers, all quantifiers for linear orders, quantifiers for isomorphism, Ramsey type quantifiers, and plenty more, showing that no sublogic ofL
(Th) or countably compact regular sublogic ofL
(Th), properly extendingL
, satisfies the uniform reduction property for quotients. As a consequence, none of these logics satisfies either-interpolation or Beth's definability theorem when closed under relativizations. We also show the failure of both properties for any sublogic ofL
(Th) in which Chang's quantifier or some cardinality quantifierQ
, with 1, is definable. |
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Keywords: | |
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