This book constitutes the refereed proceedings of the 14th International Conference on Combinatorics on Words, WORDS 2023, held in Umeå, Sweden, during June 12–16, 2023. The 19 contributed papers presented in this book were carefully reviewed and selected from 28 submissions. In addition, the volume also contains 3 invited papers. WORDS  is the main conference series devoted to combinatorics on words. This area is connected to several topics from computer science and mathematics, including string algorithms, automated proofs, discrete dynamics, number theory and, of course, classical combinatorics

The 4th International Computer Science Symposium in Russia (CSR 2009) was held August 18-23,2009 in Novosibirsk,Russia, hosted by the Sobolev Institute of Mathematics and Novosibirsk State University. It was the fourth event in the series of regular international meetings, following CSR 2006 in St. Petersburg, CSR 2007 in Ekaterinburg, and CSR 2008 in Moscow. The opening lecture was given by Andrei Voronkov, and four other invited plenary lectures were given by Sergei Odintsov, Wolfgang Thomas, Nikolai Vereshchagin, and Hongseok Yang. This volume contains all the accepted papers and some of the abstracts of the invited speakers. The scope of the proposed topics for the symposium was quite broad and covered basically all areas of computer science. We received 66 papers in total, and the Program Committee selected 29. Yandex provided the Best Student Paper Awards; the recepients of these awards were selected by the Program Committee: - Dmitry Itsykson, "Structural complexity of AvgBPP" - Yuri Pritykin and Julya Ulyashkina, "Aperiodicity measure for in?nite sequences." The reviewing processwasorganizedusing the EasyChairconferencesystem, created by Andrei Voronkov. We are grateful to our sponsors: - Russian Foundation for Basic Research - Yandex (the largest Russian Internet portal providing key Web services). We also thank the group of local organizers and in particular Pavel Salimov.