This book collects the scientific papers presented at the2nd Congress of the Italian Association for ArtificialIntelligence, held in Palermo in October 1991. It displaysthe state of the art of both Italian and European scientificresearch in AI. The book begins with an invited paper by W.Wahlster et al. The bulk of the book is then divided intofive parts on: - Knowledge representation (18 papers), -Knowledge acquisition (5 papers), - Natural language (5papers), - Perception and robotics (5 papers), -Architecture and technologies (5 papers). A sectioncontaining short papers completes the book....