III: Small: TROn - Tractable Reasoning with Ontologies

语义网是建立在描述意义的基础上的。orsemantics吗?通过元数据在网络上的数据？数据描述数据？以本体论的形式。万维网联盟（W3C）已经为本体语言制定了几个推荐的标准，这些标准在表达性和易用性方面有所不同。这些语言的核心是它们具有正式的语义，用模型理论术语表示，这使得通过自动推理可以访问隐性知识。在实践中，本体语言推理的采用正在取得进展，但要在Web上广泛采用，仍有几个障碍需要克服。两个核心技术问题是推理算法的可扩展性和本体知识库的不一致性处理。这两个问题正在这个项目中得到解决。可扩展性问题源于这样一个事实，即复杂知识的表达需要复杂的本体语言，比如Web本体语言OWL，而这种语言本身就很难进行推理。正如高计算复杂性所证明的那样，通常是exptime或更长时间。为了解决这个问题，这个项目建立在最近围绕OWL的多项式时间语言的新发展之上。特别是，在这个项目中，为目前已知的最大的多项式时间本体语言（称为ELP）开发了高效的算法和工具。通过在ELP中近似这些知识库，可以使用具有超越ELP表达能力的知识库进行推理。不一致的问题源于这样一个事实，即大型知识库，特别是在web上，通常不是集中设计的，而是由具有不同潜在观点和基本原理的不同知识库合并而成的。在这个项目中，开发了高效的工具，即不一致本体的多项式时间推理。该项目的具体成果是一个开源推理系统，它能够以至少近似的方式对OWL周围（可能）不一致的知识库进行有效的推理。欲了解更多信息，请参阅该项目的网页http://knoesis.wright.edu/faculty/pascal/projects/tron.html

The Semantic Web is based on describing the meaning ? orsemantics ? of data on the Web by means of metadata ? data describingother data ? in the form of ontologies. The World Wide Web Consortium(W3C) has made several recommended standards for ontology languageswhich differ in expressivity and ease of use. Central to theselanguages is that they come with a formal semantics, expressed inmodel-theoretic terms, which enables access to implicit knowledge byautomated reasoning.Progress in the adoption of reasoning for ontology languages inpractice is currently being made, but several obstacles remain to beovercome for wide adoption on the Web. Two of the central technicalissues are scalability of reasoning algorithms, and dealing withinconsistency of the ontological knowledge bases. These two issuesare being addressed in this project.The scalability issue has its origin in the fact that the expressionof complex knowledge requires sophisticated ontology languages, likethe Web Ontology Language OWL, which are inherently difficult toreason with ? as witnessed by high computational complexities, usuallyExpTime or beyond. This project builds on recent new developments in polynomial time languages around OWL in order to remedy this. In particular, in this project efficient algorithmizations and tools are developed for the largest currently known polynomial-time ontology language, called ELP. Reasoning with knowledge bases with expressivity beyond ELP isenabled through approximating these knowledge bases within ELP.The inconsistency issue has its origin in the fact that large knowledgebases, in particular on the web, are usually not centrally engineered,but arise out of the merging of different knowledge bases withdifferent underlying perspectives and rationales. In this project tools are developed for efficient, i.e., polynomial-time reasoning with inconsistent ontologies.The concrete outcome of the project is an open source reasoningsystem which is able to reason efficiently with (possibly)inconsistent knowledge bases around OWL, in at least an approximatemanner. For further information see the project web page at http://knoesis.wright.edu/faculty/pascal/projects/tron.html