Special Issue on Hybrid Artificial Intelligence Systems from HAIS 2021 Conference

The eight papers included in this special issue represent a selection of extended contributions presented at the 16th International Conference on Hybrid Artificial Intelligent Systems, HAIS 2021 held in Bilbao, Spain, September 22nd-24th, 2021, and organized by the BISITE group and the University of Deusto.The International Conference on Hybrid Artificial Intelligence Systems (HAIS 2021) has become a unique, established, and broad interdisciplinary forum for researchers and practitioners who are involved in developing and applying symbolic and sub-symbolic techniques aimed at the construction of highly robust and reliable problem-solving techniques to present the most relevant achievements in this field.HAIS Series of Conferences provides an interesting opportunity to present and discuss the latest theoretical advances and real-world applications in this multidisciplinary research field.