The Second World War (WW2) is arguably the most devastating catastrophe of human history, a topic of great interest to not only researchers but the general public. However, data about the Second World War is heterogeneous and distributed in various organizations and countries making it hard to utilize. In order to create aggregated global views of the war, a shared ontology and data infrastructure is needed to harmonize information in various data silos. This makes it possible to share data between publishers and application developers, to support data analysis in Digital Humanities research, and to develop data-driven intelligent applications. As a first step towards these goals, this article presents the WarSampo knowledge graph (KG), a shared semantic infrastructure, and a Linked Open Data (LOD) service for publishing data about WW2, with a focus on Finnish military history. The shared semantic infrastructure is based on the idea of representing war as a spatio-temporal sequence of events that soldiers, military units, and other actors participate in. The used metadata schema is an extension of CIDOC CRM, supplemented by various military history domain ontologies. With an infrastructure containing shared ontologies, maintaining the interlinked data brings upon new challenges, as one change in an ontology can propagate across several datasets that use it. To support sustainability, a repeatable automatic data transformation and linking pipeline has been created for rebuilding the whole WarSampo KG from the individual source datasets. The WarSampo KG is hosted on a data service based on W3C Semantic Web standards and best practices, including content negotiation, SPARQL API, download, automatic documentation, and other services supporting the reuse of the data. The WarSampo KG, a part of the international LOD Cloud and totalling ca. 14 million triples, is in use in nine end-user application views of the WarSampo portal, which has had over 690 000 end users since its opening in 2015.

中文翻译：

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WarSampo知识图：第二次世界大战中的芬兰作为关联开放数据

第二次世界大战（WW2）可以说是人类历史上最毁灭性的灾难，不仅研究人员而且公众都非常感兴趣。但是，关于第二次世界大战的数据是异类的，并且分布在各个组织和国家中，因此很难利用。为了创建汇总的战争全局视图，需要共享的本体和数据基础结构来协调各种数据孤岛中的信息。这使得在发布者和应用程序开发人员之间共享数据，支持Digital Humanities研究中的数据分析以及开发数据驱动的智能应用程序成为可能。作为实现这些目标的第一步，本文介绍了WarSampo知识图（KG），共享的语义基础结构以及用于发布有关WW2的数据的链接开放数据（LOD）服务，重点介绍芬兰的军事历史。共享语义基础结构基于将战争表示为士兵，军事单位和其他参与者参与的事件的时空序列的思想。使用的元数据模式是CIDOC CRM的扩展，并辅以各种军事历史领域本体。使用包含共享本体的基础结构，维护互连的数据带来了新的挑战，因为本体中的一项更改可以在使用它的多个数据集中传播。为了支持可持续性，已经创建了可重复的自动数据转换和链接管道，用于从单个源数据集中重建整个WarSampo KG。WarSampo KG托管在基于W3C语义Web标准和最佳实践的数据服务上，包括内容协商，SPARQL API，下载，自动文档和其他支持数据重用的服务。WarSampo KG是国际LOD云的一部分，总计约 WarSampo门户网站的九个最终用户应用程序视图中使用了1,400万个三元组，自2015年开放以来，该门户网站已拥有690,000多个最终用户。