Incomplete data is part of life and almost all areas of scientific studies. Users tend to skip certain fields when they fill out online forms; participants choose to ignore sensitive questions on surveys; sensors fail, resulting in the loss of certain readings; publicly viewable satellite map services have missing data in many mobile applications; and in privacy-preserving applications, the data is incomplete deliberately in order to preserve the sensitivity of some attribute values. Query processing is a fundamental problem in computer science, and is useful in a variety of applications. In this book, we mostly focus on the query processing over incomplete databases, which involves finding a set of qualified objects from a specified incomplete dataset in order to support a wide spectrum of real-life applications. We first elaborate the three general kinds of methods of handling incomplete data, including (i) discarding the data with missing values, (ii) imputation for the missing values, and (iii) just depending on the observed data values. For the third method type, we introduce the semantics of k-nearest neighbor (kNN) search, skyline query, and top-k dominating query on incomplete data, respectively. In terms of the three representative queries over incomplete data, we investigate some advanced techniques to process incomplete data queries, including indexing, pruning as well as crowdsourcing techniques.

This book analyzes unexpected preference query results for three problems: causality and responsibility problems, why-not and why questions, and why-few and why-many questions. Further, it refines preference queries and discusses how to modify the original preference query based on different objectives, in order to obtain satisfying results. This highly informative and carefully presented book provides valuable insights for researchers, postgraduates and practitioners with an interest in database usability.

This book constitutes the refereed proceedings of six workshops of the 14th International Conference on Web-Age Information Management, WAIM 2013, held in Beidaihe, China, June 2013. The 37 revised full papers are organized in topical sections on the six following workshops: The International Workshop on Big Data Management on Emerging Hardware (HardBD 2013), the Second International Workshop on Massive Data Storage and Processing (MDSP 2013), the First International Workshop on Emergency Management in Big Data Age (BigEM 2013), the International Workshop on Trajectory Mining in Social Networks (TMSN 2013), the First International Workshop on Location-based Query Processing in Mobile Environments (LQPM 2013), and the First International Workshop on Big Data Management and Service (BDMS 2013).

This book constitutes the thoroughly refereed proceedings of five workshops of the 13th International Conference on Web-Age Information Management, WAIM 2012, held in Harbin, China, in August 2012. The 34 revised full papers are organized in topical sections on the five following workshops: the First International Workshop on Graph Data Management and Mining (GDMM 2012), the Second International Wireless Sensor Networks Workshop (IWSN 2012), the First International Workshop on Massive Data Storage and Processing (MDSP 2012), the Third International Workshop on Unstructured Data Management (USDM 2012); the 4th International Workshop on XML Data Management (XMLDM 2012).

This book constitutes revised selected papers from the workshops of the 5th Asia-Pacific Web and Web-Age Information Management International Joint Conference on Web and Big Data, APWeb-WAIM 2021: The Fourth International Workshop on Knowledge Graph Management and Applications, KGMA 2021, The Third International Workshop on Semi-structured Big Data Management and Application, SemiBDMA 2021, and The Second International Workshop on Deep Learning in Large-scale Unstructured Data Analytics, DeepLUDA 2021, held in Guangzhou, China, in August 2021. Due to the COVID-19 pandemic the conference was held online. The 11 papers were thoroughly reviewed and selected from the 28 submissions and present recent research on the theory, design, and implementation of data management systems.

This book constitutes the proceedings of the Second International Conference on Spatial Data and Intelligence, SpatialDI 2021, which was held during April 22-24, 2021 in Hangzhou, China.The 14 full papers and 7 short papers presented in this volume were carefully reviewed and selected from 72 submissions. They are organized in the topical sections named: traffic management, data science, and city analysis.

This book constitutes the refereed conference proceedings of the 19th International Conference on Web-Based Learning, ICWL 2020, and 5th International Symposium on Emerging Technologies for Education, SETE 2020, held in Ningbo, China in October 2020.Together for the ICWL 2020 Conference and SETE 2020 Symposium 39 full papers were accepted together with 31 short papers out of 233 submissions. The papers focus on the following subjects: Semantic Web for E-Learning, through Learning Analytics, Computer-Supported Collaborative Learning, Assessment, Pedagogical Issues, E-learning Platforms, and Tools, to Mobile Learning and much more.

The two-volume set LNCS 10569 and LNCS 10570 constitutes the proceedings of the 18th International Conference on Web Information Systems Engineering, WISE 2017, held in Puschino, Russia, in October 2017. The 49 full papers and 24 short papers presented were carefully reviewed and selected from 195 submissions. The papers cover a wide range of topics such as microblog data analysis, social network data analysis, data mining, pattern mining, event detection, cloud computing, query processing, spatial and temporal data, graph theory, crowdsourcing and crowdsensing, web data model, language processing and web protocols, web-based applications, data storage and generator, security and privacy, sentiment analysis, and recommender systems.

The two-volume set LNCS 10569 and LNCS 10570 constitutes the proceedings of the 18th International Conference on Web Information Systems Engineering, WISE 2017, held in Puschino, Russia, in October 2017. The 49 full papers and 24 short papers presented were carefully reviewed and selected from 195 submissions. The papers cover a wide range of topics such as microblog data analysis, social network data analysis, data mining, pattern mining, event detection, cloud computing, query processing, spatial and temporal data, graph theory, crowdsourcing and crowdsensing, web data model, language processing and web protocols, web-based applications, data storage and generator, security and privacy, sentiment analysis, and recommender systems.