III: Small: TROn - Tractable Reasoning with Ontologies

语义网是建立在描述意义的基础上的？还是语义学？通过元数据的方式来管理Web上的数据？数据描述了其他数据吗？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标准，这些标准在表现力和易用性上有所不同。这些语言的核心是它们具有形式化的语义，以模型理论的术语表示，这使得能够通过自动推理访问隐含的知识。在实践中采用本体语言的推理目前正在取得进展，但要在Web上广泛采用，仍有几个障碍需要克服。其中两个核心技术问题是推理算法的可扩展性和处理本体知识库的不一致性。这两个问题都是在这个项目中解决的。可扩展性问题的根源在于，复杂知识的表达需要复杂的本体语言，如Web Ontology语言OWL，这些语言本质上很难推理？高度的计算复杂性证明了这一点，通常是ExpTime或更高。这个项目建立在围绕OWL的多项式时间语言的最新发展的基础上，以弥补这一点。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ELP开发了高效的算法和工具。通过在ELP中对这些知识库进行近似，可以使用表达能力超出ELP的知识库进行推理。不一致性问题的根源在于，大型知识库，特别是Web上的知识库，通常不是集中设计的，而是由具有不同底层观点和原理的不同知识库合并而成的。该项目的具体成果是一个开源的推理系统，它能够有效地利用OWL周围的(可能)不一致的知识库进行推理，至少在一个近似标志上。欲了解更多信息，请访问项目网页：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