Abstract
The papers in this issue are a selection of the papers presented at the 16th International Conference on Knowledge-Based and Intelligent Information and Engineering Systems (KES2012) held on 10, 11 and 12 September 2012, in San Sebastian, Spain. The main bias for the selection of the papers has been the proposition of foundational works or reviews that focus on some specific issues of intelligent systems and knowledge engineering. The variety of the papers collected is great going from some abstract mathematical topics up to more close to the earth applications of knowledge engineering such as information retrieval.