Nicola Guarino (born 1954, in Messina) is an Italian computer scientist and researcher in the area of Formal Ontology for Information Systems, and the head of the Laboratory for Applied Ontology (LOA), part of the Italian National Research Council (CNR) in Trento.
He may be best known in the Computer Science community for developing OntoClean, the first methodology for formal ontological analysis, with his colleague Chris Welty.
While most of the AI and KR researchers focused on reasoning algorithms and semantics of representation languages, and considered the actual knowledge expressed in these languages and reasoned over by these algorithms to be unimportant (just examples), Guarino spearheaded a counter-movement to study how knowledge should be expressed.
The rallying cry of this movement undoubted came from the well-known "Naive Physics Manifesto" paper by Patrick J. Hayes.
Guarino's work in the early 1990s began to take shape as he applied his engineering background to understand how knowledge-based systems were built and, most importantly, how the knowledge was acquired.