This paper revisits the problem of consistency maintenance when insertions or deletions are performed on a valid database containing marked nulls. This problem comes back to light in real-world linked data or RDF databases when blank nodes are associated with null values. This paper proposes solutions for the main problems one has to face when dealing with updates and constraints, namely update determinism, minimal change and leanness of an RDF graph instance. The update semantics is formally introduced and the notion of core is used to ensure a database as small as possible (i.e. the RDF graph leanness). Our algorithms allow the use of constraints such as tuple-generating dependencies, offering a way for solving many practical problems.

中文翻译：

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一致更新带有标记为null的数据库

本文将重新讨论在包含标记为null的有效数据库上执行插入或删除操作时保持一致性的问题。当空白节点与空值关联时，这个问题在现实世界中的链接数据或RDF数据库中重新暴露出来。本文提出了解决更新和约束时必须面对的主要问题的解决方案，即更新确定性，RDF图实例的最小变化和倾斜度。正式引入了更新语义，并且使用核心概念来确保数据库尽可能小（即RDF图倾斜度）。我们的算法允许使用诸如元组生成依赖项之类的约束，从而提供了解决许多实际问题的方法。