Making data and metadata FAIR (Findable, Accessible, Interoperable, Reusable)
has become an important objective in research and industry, and knowledge
graphs and ontologies have been cornerstones in many going-FAIR strategies. In
this process, however, human-actionability of data and metadata has been lost
sight of. Here, in the first part, I discuss two issues exemplifying the lack
of human-actionability in knowledge graphs and I suggest adding the Principle
of human Explorability to extend FAIR to the FAIREr Guiding Principles.
Moreover, in its interoperability framework and as part of its GoingFAIR
strategy, the European Open Science Cloud initiative distinguishes between
technical, semantic, organizational, and legal interoperability and I argue to
add cognitive interoperability. In the second part, I provide a short
introduction to semantic units and discuss how they increase 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 that instantiates a
corresponding semantic unit class. Three categories of semantic units can be
distinguished: Statement units model individual propositions, compound units
are semantically meaningful collections of semantic units, and question units
model questions that translate into queries. I conclude with discussing how
semantic units provide a framework for the development of innovative user
interfaces that support exploring and accessing information in the graph by
reducing its complexity to what currently interests the user, thereby
significantly increasing the cognitive interoperability and thus
human-actionability of knowledge graphs