This volume set, LNCS 17101 and 17102, constitutes the revised selected papers of the 20th International Conference on Computer Aided Systems Theory, EUROCAST 2026, held in Las Palmas de Gran Canaria, Spain, during February 23–27, 2026.

The 135 full papers included in these volumes were carefully reviewed and selected from 200 submissions. EUROCAST is entirely composed of workshops with the following topical sections:

Part I: Systems Theory, Applications, Pioneers, and Landmarks; Theory and Applications of Metaheuristic Algorithms; Mechatronic Product Development; Model-Based System Design, Verification and Simulation; Applications of Signal Processing Technology; Applied Data Science and Engineering for Intelligent Transportation Systems and Smart Mobility; Computer and Systems Based Methods and Electronic Tools in Clinical and Academic Medicine; Systems in Industrial Robotics, Automation and IoT; Systems Thinking and Systems Simulation: An Interdisciplinary Approach to Modeling Complexity;

Part II: Data Science in Medical and Bio-Informatics; Modeling, Simulation, and Optimization in Production and Logistics; "Green AI" and SW-Tools for Sustainable Energy and Materials Consumption; Stochastic Models, Statistical Methods, and Applied Systems Simulations; Impact of AI and Quantum Technologies on Cybersecurity; Indoor Positioning and Localization; Blackbox Systems for Generative AI - Explainability and Applications; Cybermedical Systems as Human-Centered AI and Digital Medicine Applications; Innovative Teaching Approaches in Computer Science and Automation: Methods, Tools, and Experiences.