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On the complexity of existential positive queries
ACM Transactions on Computational Logic
We systematically investigate the complexity of model checking the existential positive fragment of first-order logic. In particular, for a set of existential positive sentences, we consider model checking where the sentence is restricted to fall into the set; a natural question is then to classify which sentence sets are tractable and which are intractable. With respect to fixed-parameter tractability, we give a general theorem that reduces this classification question to the correspondingdoi:10.1145/2559946 fatcat:s2o4gwaldvfari5qziuiosm7hi