This book constitutes the refereed proceedings of the First International Conference on Web Reasoning and Rule Systems, RR 2007, held in Innsbruck, Austria in June 2007 as a merger of the three previously separate events: International Workshop on Principles and Practice of Semantic Web Reasoning (PPSWR), the International Conference on Rules and Rule Markup Languages for the Semantic Web (RuleML), and the International Workshop on Reasoning on the Web (RoW).

The 14 revised full papers, 15 revised short papers presented together with 7 poster papers were carefully reviewed and selected from over 60 submissions. The papers address all current topics in Web reasoning and rule systems such as acquisition of rules and ontologies by knowledge extraction, design and analysis of reasoning languages, implemented tools and systems, standardization, ontology usability, ontology languages and their relationships, rules and ontologies, reasoning with uncertainty, reasoning with constraints, rule languages and systems, semantic Web services modeling and applications.

This book constitutes revised selected papers from the 16th and 17th International Conferences on Web Information Systems and Technologies, WEBIST 2020 and WEBIST 2021, which took place virtually in November 2020 and October 2021, respectively.The 10 full papers from WEBIST 2021 and 1 full paper from WEBIST 2020 presented in this volume were carefully reviewed and selected from originally 48 paper submissions in 2020 and 107 submissions in 2021. The selected papers contribute to the understanding of relevant current research trends in Web information systems and technologies, including deep learning, knowledge representation and reasoning, recommender systems, internet of things, Web intelligence and big data.

The Reasoning Web summer school series is a well-established event, attracting experts from academia and industry as well as PhD students interested in fo- dational and applicational aspects of the Semantic Web. This volume contains thelecturenotesofthefourthsummerschool, which took place in Venice, Italy, in September 2008. This year, the school focussed on a number of important application domains, in which semantic web techniques have proved to be p- ticularly e?ective or promising in tackling problems. The ?rst three chapters provide introductory material to: - languages, formalisms, and standards adopted to encode semantic information; - "soft" extensions that might be useful in contexts such as multimedia or social network applications; - controlled natural language techniques to bring ontology authoring closer to end users. The remaining chapters cover major application areas such as social networks, semantic multimedia indexing and retrieval, bioinformatics, and semantic web services. Thepresentationshighlightedwhichtechniquesarealreadybeingsuccessfully applied for purposes such as improving the performance of information retrieval algorithms, enablingtheinteroperationofheterogeneousagents, modellinguser's pro?les and social relations, and standardizing and improving the accuracy of very large and dynamic scienti?c databases. Furthermore, the lectures pointed out which aspects are still waiting for a solution, andthepossiblerolethatsemantictechniquesmayplay, especiallythose reasoningmethodsthathavenotyetbeenexploitedtotheirfullpotential.Wehope thatthe school'smaterialwillinspire further exciting researchinthese areas. We are grateful to all the lecturers and their co-authors for their excellent contributions, to the Reasoning Web School Board, and Norbert Eisinger in particular, who helped in several critical phases, and to the organizations that supported this event: the University of Padua, the MOST project, and the N- work of Excellence REWERSE.