The FAIREr Guiding Principles: Organizing data and metadata into semantically meaningful types of FAIR Digital Objects to increase their cognitive interoperability and human explorability

Ensuring the FAIRness (Findable, Accessible, Interoperable, Reusable) of data and metadata is an important goal in research and industry. Knowledge graphs and ontologies have been central in achieving this goal, with interoperability receiving much attention. The European Open Science Cloud Interoperability Framework (EOSC IF) distinguishes four layers of interoperability: technical, semantic, organizational, and legal. This paper argues that the emphasis on machine-actionability has overshadowed the essential need for human-actionability of data and describes two cases within knowledge graphs in which human-actionability is challenged. In response, it propagates incorporating cognitive interoperability as fifth layer within the EOSC IF and discusses the relation between human explorability and cognitive interoperability, resulting in the suggestion to add the Principle of human Explorability, extending FAIR to the FAIREr Guiding Principles. The subsequent sections present the concept of semantic units, elucidating their importance in enhancing the human explorability and cognitive interoperability of knowledge graphs. Semantic units structure a knowledge graph into identifiable and semantically meaningful subgraphs, each represented with its own resource constituting a FAIR Digital Object (FDO) that instantiates a corresponding FDO class. Various categories of FDOs are distinguished. The content of a FDO can be displayed in a user interface either as a mind-map-like graph or as natural language text. Organizing knowledge graphs into FDOs based on semantic units supports the cognitive interoperability of data and metadata and facilitates their human explorability. The development of innovative user interfaces enabled by such FDOs empowers users to access, navigate, and explore information in knowledge graphs with enhanced efficiency.