The research of Professor P. Brézillon focuses since 1992 on the study of Intelligent Assistant Systems, and particularly the aspects as explanation, context, and incremental knowledge acquisition. Since several years, the emphasis of his studies is on the notion of context. Professor P. Brézillon is the instigator of the series of international and interdisciplinary conferences (biannual) on modeling and using context from 1997 (in Rio de Janeiro, Brasil) to 2019 (in Trento, Italy).He has published about 450 papers in international conferences and international journals (e.g., IEEE Expert, AI Magazine, The Knowledge Engineering Review, and the International Journal on Human-Computer Studies). He has been the chair of several workshops (at ECAI, IJCAI, etc.), co-organizer of two international conferences in the AI area, member of 191 program committees, and has given several invited talks and tutorials.Professor P. Brézillon is the Coordinator of about twenty real-world projects and participates in 40 contract managements. For example, the SART project with the subway company in Paris (France) is a real-world application dealing explicitly with context  from 1995 to 2002. The SART project met around 50 persons in France (Paris) and Brazil (Rio de Janeiro) for developing an intelligent assistant system to support the responsible of subway lines in incident situation. The French Foreign Ministry retained SART as a leader project in the France-Brazil cooperation. Professor P. Brézillon also intervenes in several projects in medicine, mainly around breast cancer diagnosis.

• Preface.- Introduction.- The real-World applications.- Operational Knowledge and context.- From context modeling to implementation for individuals.- From context modeling to implementation for group activity.- Discussion and lessons learned.- Conclusion.

The research of Professor P. Brézillon focuses since 1992 on the study of Intelligent Assistant Systems, and particularly the aspects as explanation, context, and incremental knowledge acquisition. Since several years, the emphasis of his studies is on the notion of context. Professor P. Brézillon is the instigator of the series of international and interdisciplinary conferences (biannual) on modeling and using context from 1997 (in Rio de Janeiro, Brasil) to 2019 (in Trento, Italy).He has published about 450 papers in international conferences and international journals (e.g., IEEE Expert, AI Magazine, The Knowledge Engineering Review, and the International Journal on Human-Computer Studies). He has been the chair of several workshops (at ECAI, IJCAI, etc.), co-organizer of two international conferences in the AI area, member of 191 program committees, and has given several invited talks and tutorials.Professor P. Brézillon is the Coordinator of about twenty real-world projects and participates in 40 contract managements. For example, the SART project with the subway company in Paris (France) is a real-world application dealing explicitly with context  from 1995 to 2002. The SART project met around 50 persons in France (Paris) and Brazil (Rio de Janeiro) for developing an intelligent assistant system to support the responsible of subway lines in incident situation. The French Foreign Ministry retained SART as a leader project in the France-Brazil cooperation. Professor P. Brézillon also intervenes in several projects in medicine, mainly around breast cancer diagnosis.

• Preface.- Introduction.- The real-World applications.- Operational Knowledge and context.- From context modeling to implementation for individuals.- From context modeling to implementation for group activity.- Discussion and lessons learned.- Conclusion.