Description:This book presents the refereed proceedings of the 12th Annual International Computing and Combinatorics Conference, COCOON 2006, held in Taipei, Taiwan, in August 2006.The 52 revised full papers presented together with abstracts of 2 invited talks were carefully reviewed and selected from 137 submissions. The papers are organized in topical sections on computational economics, finance, and management, graph algorithms, computational complexity and computability, quantum computing, computational biology and medicine, computational geometry, graph theory, computational biology, graph algorithms and applications, on-line algorithms, algorithms for security and systems, discrete geometry and graph theory, approximation algorithms, and experimental algorithms.