WSTST’05 Plenary Abstracts -- Neural Networks -- Fuzzy Systems -- Image Processing -- Computer Security -- Agent Based Systems -- Soft Computing and Hard Computing -- Chance Discovery -- Medicine and Biology -- Humanized Computational Intelligence -- Civil and Environmental Engineering -- Web Intelligence -- Intelligent Hybrid Systems -- Swarm Intelligence and Patterns -- Data Mining and Knowledge Management -- Financial Modeling -- Information Processing Systems -- Evolutionary Algorithms, Search and Optimization -- Collaborative Learning Systems.This book presents the proceedings of the Fourth International Workshop on Soft Computing as Transdisciplinary Science and Technology (WSTST '05), May 25-27, 2005, Muroran, Japan. It brings together the original work of international soft computing/computational intelligence researchers, developers, practitioners, and users. This proceedings provide contributions to all areas of soft computing including intelligent hybrid systems, agent-based systems, intelligent data mining, decision support systems, cognitive and reactive distributed artificial intelligence (AI), internet modelling, human interface, and applications in science and technology.