Senior Lecturer in Knowledge Based Systems, BCIM Faculty, The Knowledge Based Systems Centre, London South Bank University,

Abstract Intelligent systems encompass a wide range of software technologies including heuristic and normative expert systems, case-based reasoning systems, and neural networks. This field has been augmented in recent years by Web-based applications, such as recommender systems and the semantic Web. The uses of explanation facilities have their roots in heuristic rule-based expert systems and have long been touted as an important adjunct in intelligent decision support systems. However, in recent years, their uses have been explored in many other intelligent system technologies- particularly those making an impact in e-commerce such as recommender systems. This paper shows how explanation facilities work with a range of symbolic intelligent techniques and, when carefully designed, provide a range of benefits. The paper also shows how, despite being more difficult to augment with non-symbolic technologies, hybrid methods predominantly using rule-extraction techniques have provided moderate success for explanation facilities in a range of ad-hoc applications