This book constitutes the refereed proceedings of the 34th International Workshop on Combinatorial Algorithms, IWOCA 2023, held in Tainan, Taiwan, during June 7–10, 2023.  The 33 full papers included in this book were carefully reviewed and selected from 86 submissions. They were organized in topical sections as follows: algorithms and data structures; algorithmic and combinatorical aspects of cryptography and information security; algorithmic game theory and complexity of games; approximation algorithms; complexity theory; combinatorics and graph theory; combinatorial generation, enumeration and counting; combinatorial optimization; combinatorics of words; computational biology; computational geometry; decompositions and combinatorial designs; distributed and network algorithms; experimental combinatorics; fine-grained complexity; graph algorithms and modelling with graphs; graph drawing and graph labelling; network theory and temporal graphs; quantum computing and algorithms for quantum computers; online algorithms; parameterized and exact algorithms; probabilistic and randomized algorithms; and streaming algorithms.

This book constitutes the refereed proceedings of the 25th International Computer Symposium on New Trends in Computer Technologies and Applications, ICS 2022, which took place in Taoyuan, Taiwan, in December 2022. ICS is one of the largest joint international IT symposia held in Taiwan. Founded in 1973, it is intended to provide a forum for researchers, educators, and professionals to exchange their discoveries and practices, and to explore future trends and applications in computer technologies. The biannual symposium offers a great opportunity to share research experiences and to discuss potential new trends in the IT industry. The 58 full papers and one invited paper presented in this volume were carefully reviewed and selected from 137 submissions. The papers have been organized in the following topical sections: Invited Paper; Algorithms, Bioinformatics, and Computation Theory; Cloud Computing and Big Data; Computer Vision and Image Processing; Cryptography and Information Security; Electronics and Information Technology; Mobile Computation and Wireless Communication; Ubiquitous Cybersecurity and Forensics.