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An Algebraic Preservation Theorem for Aleph-Zero Categorical Quantified Constraint Satisfaction
(Logical Methods in Computer Science c/o Institut f. Theoretische Informatik, Technische Universität Braunschweig, 2013-03-29)
We prove an algebraic preservation theorem for positive Horn definability in aleph-zero categorical structures. In particular, we define and study a construction which we call the periodic power of a structure, and define ...
Beyond Q-Resolution and Prenex Form: a Proof System for Quantified Constraint Satisfaction
(Technische Universität Braunschweig, Institute of Theoretical Computer Science, 2014)
We consider the quanti fied constraint satisfaction problem (QCSP) which is to decide, given a structure and a first-order sentence (not assumed here to be in prenex form) built from conjunction and quanti fication, whether ...