Constraint Satisfaction Problems and Homomorphism Versions of Ultrafilter Axioms
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چکیده
We define filter-tolerant powers of finite relational structures, and consider the problem of retracting such structures to their diagonal. We show that for some structures, such retractions can be readily derived from the axioms of Zermelo and Fraenkel, while at the other extreme, there are structures for which the existence of such retractions is equivalent to the ultrafilter axiom.
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تاریخ انتشار 2016