Revealing Medieval Manuscript Treasures: Semantic Web Integration through a Polymorphic Knowledge Graph and Linked Open Data

Medieval manuscripts represent rich and heterogeneous cultural heritage resources, offering interdisciplinary insights into historical context, textual content, physical features, and artistic elements. However, integrating such diverse data remains challenging due to inconsistencies in metadata schemas and variations in data quality. This article addresses these challenges through a semantic web-based approach applied to two distinctive medieval manuscript collections: Progetto Irnerio and Mosaico. It presents an extension of the existing Medieval Manuscript Data Integration Ontology (MMDIO), originally developed using the MeLOn methodology and evaluated with the FOCA framework. This extended ontology builds upon the previously published MeMO ontology, introducing new classes and relationships designed specifically for the integration of medieval manuscript data. A key contribution is the construction of a Polymorphic Knowledge Graph that semantically integrates heterogeneous datasets from both collections, enabling faceted search, semantic browsing, and advanced visualization. Additionally, the MELIORATE Linked Open Data (LOD) platform is developed to provide unified, interoperable online access to manuscript content, significantly enhancing data accessibility and supporting interdisciplinary collaboration. This integrated approach demonstrates the potential of semantic web technologies to bridge disciplinary gaps among Digital Humanities, Legal Studies, and Computer Science, offering new methodological opportunities for cultural heritage research and digital preservation.