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## Abstract

Operational consistent query answering (CQA) is a recent framework for CQA, based on revised definitions of repairs and consistent answers, which opens up the possibility of efficient approximations with explicit error guarantees. The main idea is to iteratively apply operations (e.g., fact deletions), starting from an inconsistent database, until we reach a database that is consistent w.r.t. the given set of constraints. This gives us the flexibility of choosing the probability with which we apply an operation, which in turn allows us to calculate the probability of an operational repair, and thus, the probability with which a consistent answer is entailed. A natural way of assigning probabilities to operations is by targeting the uniform probability distribution over a reasonable space such as the set of operational repairs, the set of sequences of operations that lead to an operational repair, and the set of available operations at a certain step of the repairing process. This leads to what we generally call uniform operational CQA. The goal of this work is to perform a data complexity analysis of both exact and approximate uniform operational CQA, focusing on functional dependencies (and subclasses thereof), and conjunctive queries. The main outcome of our analysis (among other positive and negative results), is that uniform operational CQA pushes the efficiency boundaries further by ensuring the existence of efficient approximation schemes in scenarios that go beyond the simple case of primary keys, which seems to be the limit of the classical approach to CQA.

Original language | English |
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Title of host publication | Proceedings of the 41st ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems |

Place of Publication | New York, NY, USA |

Publisher | Association for Computing Machinery (ACM) |

Pages | 393–402 |

Number of pages | 10 |

ISBN (Print) | 9781450392600 |

DOIs | |

Publication status | Published - 13 Jun 2022 |

Event | The 41st ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems - Philadelphia, United States Duration: 13 Jun 2022 → 15 Jun 2022 Conference number: 41 |

### Publication series

Name | PODS '22 |
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Publisher | Association for Computing Machinery |

### Symposium

Symposium | The 41st ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems |
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Abbreviated title | PODS 2022 |

Country/Territory | United States |

City | Philadelphia |

Period | 13/06/22 → 15/06/22 |

## Keywords

- conjunctive queries
- inconsistency
- consistent query answering
- randomized approximation schemes
- operational semantics
- functional dependencies

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