This book constitutes the thoroughly refereed post conference proceedings of the 4th edition of
the Semantic Web Evaluation Challenge SemWebEval 2018 co-located with the 15th European
Semantic Web conference held in Heraklion Greece in June 2018. This book includes the
descriptions of all methods and tools that competed at SemWebEval 2018 together with a
detailed description of the tasks evaluation procedures and datasets. The 18 revised full
papers presented in this volume were carefully reviewed and selected from 24 submissions. The
contributions are grouped in the areas: the mighty storage challenge open knowledge extraction
challenge question answering over linked data challenge semantic sentiment analysis.
