arXiv 0810.22702008-10math.LOmath.RA

The reducts of equality up to primitive positive interdefinability

Manuel Bodirsky, Hubie Chen, Michael Pinsker

备注：: 41 pages; version 3 has been been checked also by non-authors

英文摘要：

We initiate the study of reducts of relational structures up to primitive positive interdefinability: After providing the tools for such a study, we apply these tools in order to obtain a classification of the reducts of the logic of equality. It turns out that there exists a continuum of such reducts. Equivalently, expressed in the language of universal algebra, we classify those locally closed clones over a countable domain which contain all permutations of the domain.

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