Over the last decade, knowledge graphs have multiplied, grown, and evolved on the World Wide Web, and the advent of new standards, vocabularies, and application domains has accelerated this trend. IndeGx is a framework leveraging an extensible base of rules to index the content of KGs and the capacities of their SPARQL endpoints. In this article, we show how knowledge representation (KR) and reasoning methods and techniques can be used in a reflexive manner to index and characterize existing knowledge graphs (KG) with respect to their usage of KR methods and techniques. We extended IndeGx with a fully ontology-oriented modeling and processing approach to do so. Using SPARQL rules and an OWL RL ontology of the indexing domain, IndeGx can now build and reason over an index of the contents and characteristics of an open collection of public knowledge graphs. Our extension of the framework relies on a declarative representation of procedural knowledge and collaborative environments (e.g., GitHub) to provide an agile, customizable, and expressive KR approach for building and maintaining such an index of knowledge graphs in the wild. In doing so, we help anyone answer the question of what knowledge is out there in the world wild Semantic Web in general, and we also help our community monitor which KR research results are used in practice. In particular, this article provides a snapshot of the state of the Semantic Web regarding supported standard languages, ontology usage, and diverse quality evaluations by applying this method to a collection of over 300 open knowledge graph endpoints.

翻译：过去十年间，知识图谱在万维网上不断增殖、增长与演化，而新标准、新词汇表以及新应用领域的出现加速了这一趋势。IndeGx是一个利用可扩展规则库来索引知识图谱内容及其SPARQL端点能力的框架。本文展示了如何以自反方式运用知识表示与推理方法技术，针对现有知识图谱对KR方法与技术的使用情况进行索引与特征描述。为此，我们采用完全面向本体的建模与处理方法对IndeGx进行了扩展。通过使用SPARQL规则和索引领域的OWL RL本体，IndeGx如今能够构建并推理一个开放公共知识图谱集合的内容与特征索引。本框架的扩展依赖于对过程性知识与协作环境（如GitHub）的声明式表示，从而为构建和维护现实世界中此类知识图谱索引提供了一种敏捷、可定制且富有表现力的KR方法。通过这项工作，我们帮助人们解答广义上开放语义网中存在何种知识的问题，同时协助本领域社区监测哪些KR研究成果在实践中得到应用。特别地，本文通过将此方法应用于包含300多个开放知识图谱端点的集合，提供了关于语义网在支持标准语言、本体使用情况及多样化质量评估方面的现状快照。