Preface to special issue on Inductive Logic Programming, ILP 2017 and 2018

This special issue followed the 27th International Conference on Inductive Logic Programming, held in Orléans, France (September 4–6, 2017), and preceded the 28th edition, held in Ferrara, Italy (September 2–4, 2018). For ILP 2018, two different tracks were organized, defining six kinds of submissions: 1. a Journal Track, 2. a Conference Track, allowing five types of submissions (long papers (regular or up-and-coming), short papers, works in progress, papers already published or accepted). The Journal track welcomed original papers to be published in this special issue, gathering both extended versions of papers submitted at ILP 2017 and new submissions for 2018. In the open call for papers, we solicited submissions on theoretical aspects of ILP, learning in different representations, development of algorithms and systems, and applications of ILP. We received eight submissions, and we selected four of them for inclusion in this special issue. The articles have been peer-reviewed according to the journal’s high standards.