1 © The ATHENA Consortium. Semantics Semantics – ancient Greek for meaning σημαίνω – I signal, sign, show Semantics has become a buzzword or even a fuzzword Example from a book about Eclipse: –“We’ll use the same mechanisms to navigate semantic errors (…) that we use to navigate compile errors.” –(failing tests) – semantic error is less precise than “failing tests” –a fuzzword in this case Oxford English Dictionary: 2. a. Relating to signification or meaning. (as adjective)

2 © The ATHENA Consortium. Semantics and Definitions Standard way to communicate meaning is by definition definition: “Verbal description of a concept, permitting its differentiation from other concepts within a system of concepts.” – International Standard ISO 1087, Terminology – Vocabulary, 1990 The Semantic Web is about formalizing your definitions “the Semantic Web, as envisioned by Tim Berners-Lee and many others since, is a logical extension of the current Web that enables explicit [machine-processable] representations of term meanings [concepts]” – Frankel, David; Hayes, Pat; Kendall, Elisa; McGuinness, Deborah: MDA Journal July 2004

3 © The ATHENA Consortium. Formality Spectrum: informal SAPterm WordNet Informal

4 © The ATHENA Consortium. Formality Spectrum: formal SAPterm WordNet "An ontology is an explicit and formal specification of a shared conceptualization" Ontology, e.g, OWL ontology Informal Formal Every tomato is red. for all x ( tomato (x) implies red (x) )