Abstract
<jats:p>Certificate request procedures across public administrations (PAs) often depend on heterogeneous repositories, data models, and validation rules, thereby limiting interoperability and automation. This study presents a semantic digital library built on an RDF/OWL ontology and a knowledge graph representing certificates, administrative entities, required documents, attributes, dependencies, and processing rules. Linked Open Data and SPARQL interfaces extend the initially centralized model and connect it to certificate-management microservices. The resulting architecture enables distributed access to shared semantic definitions and supports the Once-Only principle. To inform implementation priorities, we compare five graph measures with certificate request volumes from the Italian National Resident Population Registry (ANPR). PageRank yields the highest observed correlation (r = 0.6455), narrowly exceeding Betweenness and Closeness Centrality (r = 0.6386). This result suggests that indirect structural dependencies may help identify high-priority services; however, the limited matched dataset makes the analysis exploratory. The framework provides a foundation for interoperable certificate services and future integration with national semantic infrastructures such as SCHEMA.gov.it.</jats:p>