CS&P’18 preface Preface This volume contains the papers presented at CS&P’18, the 27th International Workshop on Concurrency, Specification and Programming, held on September 24-26 2018 in Berlin. Since the early seventies Warsaw University and Humboldt University have alternately or- ganized an annual workshop - since the early nineties known as CS&P. Over time, it has grown from a bilateral seminar to a well-known meeting attended also by colleagues from many other countries than Poland and Germany. During the three-day meeting, there are 8 sessions and a number of short presentations on current and emerging topics, as well as open discussions. While sessions on Concurrency, Veri- fication and Programming have always been part of the CS&P, we are delighted to add sessions on the topics Learning Systems and Reaction Systems to this years program. Furthermore, there are two invited talks: Prof. Matthias Weidlich will give a presentation on the ”Formal Analysis of Complex Event Processing” and Prof. Wojciech Penczek will speak on ”Improving Efficiency of Model Checking for Variants of Alternating-time Temporal Logic”. This volume contains 21 papers supplementing the presentations and invited talks, selected from the submissions by the program committee. Following the workshops tradition, we strive to retain an informal working atmosphere. Therefore, the proceedings includes drafts and extended abstracts as well as fully elaborated contributions. The proceedings are published by Humboldt University and CEUR. The editors would like to thank the university’s printing office, the team at CEUR Workshop Proceedings, and EasyChair for their help in producing this publication. September 26, 2018 Holger Schlingloff & Samira Akili i