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Linear Programs with Conjunctive Queries Capelli, Florent Crosetti, Nicolas Niehren, Joachim Ramon, Jan Database queries linear programming hypergraph decomposition In this paper, we study the problem of optimizing a linear program whose variables are the answers to a conjunctive query. For this we propose the language LP(CQ) for specifying linear programs whose constraints and objective functions depend on the answer sets of conjunctive queries. We contribute an efficient algorithm for solving programs in a fragment of LP(CQ). The naive approach constructs a linear program having as many variables as there are elements in the answer set of the queries. Our approach constructs a linear program having the same optimal value but fewer variables. This is done by exploiting the structure of the conjunctive queries using generalized hypertree decompositions of small width to factorize elements of the answer set together. We illustrate the various applications of LP(CQ) programs on three examples: optimizing deliveries of resources, minimizing noise for differential privacy, and computing the s-measure of patterns in graphs as needed for data mining. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Florent Capelli and Nicolas Crosetti and Joachim Niehren and Jan Ramon 2022 Is Part Of LIPIcs, Volume 220, 25th International Conference on Database Theory (ICDT 2022) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.ICDT.2022.5 urn:nbn:de:0030-drops-158796 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2022.5 eng https://creativecommons.org/licenses/by/4.0/legalcode