Formal Definition of the Term “Semantics” as a Foundation for Semantic Interoperability in the Industrial Internet of Things

Abstract Semantic interoperability is seen as the key to realize the ideas of the Industrial Internet of Things (IIoT). In order to equip technical systems with such a capability, a precise definition of the term “semantics” is needed. Complex IIoT devices can only be developed properly on a formal foundation. Existing approaches that intend to specify the term “semantics” are often more intuitively motivated. These include, for example, the knowledge pyramid or the Levels of Conceptual Interoperability Model (LCIM). The paper provides a formal definition of the term “semantics” and relates these existing approaches critically to the proposed definition.