HEXER: An Online Tool for Building, Validating and Exploring Knowledge Graphs from Historical Documents

Abstract

Digitisation improves access to historical documents, but it does not, by itself, make them easy to navigate. Entity recognition and linking can identify recurring people, organizations, places, and events across an extended source. Yet the resulting dataset can appear authoritative before it has been reviewed, and translated or transcribed materials are especially affected by human or machine generated errors. We present the HEXER Graph Explorer, a self-hosted browser-based application that addresses both challenges within a unified interface. First, it facilitates the construction and validation of a knowledge graph from a historical document. A selected language model generates candidate entities, relations, Wikidata matches, and each element is accompanied by its supporting text passage, confidence ranking, and explicit review status. Curators can compare ranked candidates, amend metadata, merge duplicate records, or leave uncertain entries unresolved. Their decisions are recorded in a non destructive manner, as appends to the original data, thus making them easily reversible. Furthermore, all decisions are logged and transparently displayed. Second, the tool enables semantic rather than page-based exploration of the document. Readers navigate the corpus through thematic lenses, for example, vessels and military service, places and routes, peoples and languages. Filters based on entities or relations can trace any connection back to the sentences from which they are inferred. The demonstration is based on a historical document, the journal of a Transylvanian sailor who was held as a prisoner of war in Japan from 1914 to 1919, where he wrote his memories, and whose account is available through Europeana.