Referring Expression based Identification in Information Systems

身份管理是数据库和信息系统的一个重要组成部分：当实体和实体之间的关系存储在信息系统中时，必须找到一种明确的唯一标识这些实体的方法。当前的解决方案通常依赖于在基于对象的方法中引入通用标识符（“代理”），或者需要外部基于值的键，即在关系系统中唯一标识对象的属性元组。这两种方法都有许多缺点。前者本质上要求所有已知的单个对象具有唯一的区分标识符。这些标识符通常不足以让人类用户弄清楚他们引用的是什么真实世界的对象，因为它们在语义上是不透明的。一个具体的例子是个体作者或系统必须在社区开发的本体（如Freebase）中发明的标识符（其中警察的“Synchronicity”专辑标识符是“/guid/9202a8c04000641f8000000002f9e349”）。另一方面，当必须集成来自异构信息系统的数据时，使用外部键会导致问题。

Management of identity is an essential component of database and information systems: when entities, and relationships between entities, are stored in an information system, a clear way of uniquely identifying such entities must be found. Current solutions typically rely on introducing universal identifiers ("surrogates") in object-based approaches or require external value-based keys, tuples of attributes that uniquely identify objects in relational systems. Both these approaches suffer from numerous shortcomings. The former essentially requires all known individual objects to have unique distinguishing identifiers. These identifiers are often insufficient to allow human users to figure out what real-world object they refer to, since they are semantically opaque. A specific example are identifiers that individual authors or the system must invent in community-developed ontologies such as Freebase (where the identifier of the "Synchronicity" album by the Police is "/guid/9202a8c04000641f8000000002f9e349"). On the other hand, using external keys leads to problems when data from heterogeneous information systems must be integrated. Additional problems for finding identifying attributes arise in conceptual modelling. For example, in the case where Extended Entity-Relationship modelling creates a new heterogeneous entity set by generalization, a new auxiliary and an artificial identifier is commonly required to apply uniformly to all instances, despite the fact that all the entities are already properly identified. The goal of the proposed research is to develop a comprehensive theory for identifying entities in information systems based on the notion of a referring expression. In linguistics, a referring expression is any noun phrase identifying an object in a way that will be useful to interlocutors. In information systems, these interlocutors range from end-users issuing queries, to other computer systems communicating with the system at hand. In both cases, a common way of identifying objects is essential for such communication to make sense. The proposal is structured around the notion of referring expressions expressed as unary formulas in first-order logic that, in the appropriate context, are true of a single individual in the universe of discourse and in this way indirectly identify such an individual. We call such formulas singular referring expressions. The research will address many issues relating to the use of the singular referring expressions in information systems ranging from theoretical issues related to general expressive power, computational properties, and on the limits of logic-based referring expressions, to designing fragments of first-order logic with more amenable computational properties, e.g., in the area of query answering, to design methodologies for developing information systems with focus on identity management.