The logic of consistent query answering in database

由于几个原因，数据库可能包含不一致的信息，即违反某些完整性约束。申请人和合著者将一致性数据描述为在恢复原始数据库一致性的最小形式下不变的数据。其思想是在不清理给定数据库的情况下对这些一致的信息进行计算访问，并尽可能避免计算和查询数据库的可选一致版本的昂贵操作（修复）。相反，该方法包括在查询时检索一致的、语义正确的信息。虽然在这方面取得了许多进展，但在这方面的研究中仍存在一些概念和技术上的开放性问题。我们将在本项目中解决的一些问题如下：(a)从语义和操作的角度开发管理数据库中一致数据推理的逻辑，特别是一致的查询回答。(b)处理在这方面缺乏完整资料的问题。(c)为了一致地回答更复杂的查询，组合先前（缓存）一致结果的可能性，以及在此过程中使用辅助视图。(d)处理必须这样处理的数字属性，而不是一般数据类型。(e)在容易违反全局约束的虚拟数据集成系统中一致地回答复杂查询。(f)非关系数据库（如XML、RDF）的一致查询应答。(g)对等方之间一致的数据交换等。

For several reasons databases may contain inconsistent information, i.e. that participates in the violation of certain integrity constraints. The applicant and coauthors have characterized the consistent data as the one that is invariant under minimal forms of restoration of the consistency of the original database. The idea is to have computational access to this consistent information without having to clean the given database, and avoiding as much as possible the costly operation of computing and querying the alternative consistent versions of the database (the repairs). Rather, the approach consists in retrieving the consistent, semantically  correct information at query time. Although many progresses have been made in this area, there are still several conceptual and technical open problems in this line of research. Some of those we will address in this project are the following: (a) Developing, in semantic and operational terms, the logic that governs reasoning with and about consistent data in databases, and consistent query answering, in particular. (b) Dealing with absence of complete information in this context. (c) Possibility of composing previous (chached) consistent results in order  to consistently answer more complex queries, and the use of auxiliary views in this process. (d) Dealing with numerical attributes that have to be treated as such, as opposed to generic datatypes. (e) Consistent answering of complex queries in virtual data integration systems that easily violate global constraints. (f) Consistent query answering in non-relational database, e.g. XML, RDF. (g) Consistent exchange of data between peers, etc.