Article ID Journal Published Year Pages File Type
419745 Discrete Applied Mathematics 2009 11 Pages PDF
Abstract

The Galois closure on the set of relations invariant to all finite partial automorphisms (automorphisms) of a countable partial structure is established via quantifier-free infinite predicate languages (infinite languages with finite string of quantifiers respectively). Based on it the homogeneous and strictly homogeneous criteria for a countable partial structure as well as an ultrahomogeneous criterion for a countable relational structure are found. Next it is shown that infinite languages with a finite string of quantifiers cannot determine the corresponding Galois closure for relations invariant to all automorphisms of an uncountable partial structure.

Related Topics
Physical Sciences and Engineering Computer Science Computational Theory and Mathematics
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