<p>Hypermedia systems and knowledge systems can be viewed as flip sides of the same coin. The former are designed to convey information and the latter to solve problems; developments beyond the basic techniques of each system type require techniques from the other type. Both system types are frequently used in learning environments, and to different extent utilise user co-operation.</p><p>A knowledge system consists of a formal representation of a domain theory enabling automated reasoning to take place within the domain. Since a formalisation cannot generally reproduce all relevant knowledge, the user's co-operation is needed to obtain a well functioning system. To perform well in this co-operation, the knowledge in the system must be accessible and transparent to the user. Tranparency can be achieved by means of explanations. In a learning environment transparency and co-operation are vital because the user needs to be active whilst the reasoning is being carried out - to be able to learn how to perform the problem solving.</p><p>To achieve transparency we introduce the notions of inferential context and conceptual context. These allow explanations to be composed at various levels of abstraction and from different perspectives and not only exploit a formalisation, but also informal descriptions of the domain knowledge. This facilitates the user’s learning of the domain knowledge and thus his/her ability to co-operate with the system in the problem solving.</p><p>We integrate techniques from knowledge systems and hypermedia in a system architecture. The architecture deals with formal and informal knowledge. The formal knowledge is used for the formal reasoning, which is based on knowledge systems techniques; the informal knowledge is exploited in this reasoning to generate explanations in different media. The relations between the formal and the informal theory are administered by a metatheory. The metatheory carries out the reasoning in the system and the communication with the user, i.e. the presentation of the explanations and the integration of the user's contribution in the reasoning. The system architecture is transparent, modular and promotes clarity, maintainability and reusability.</p>

Hypermedia systems and knowledge systems can be viewed as flip sides of the same coin. The former are designed to convey information and the latter to solve problems; developments beyond the basic techniques of each system type require techniques from the other type. Both system types are frequently used in learning environments, and to different extent utilise user co-operation. A knowledge system consists of a formal representation of a domain theory enabling automated reasoning to take place within the domain. Since a formalisation cannot generally reproduce all relevant knowledge, the user's co-operation is needed to obtain a well functioning system. To perform well in this co-operation, the knowledge in the system must be accessible and transparent to the user. Tranparency can be achieved by means of explanations. In a learning environment transparency and co-operation are vital because the user needs to be active whilst the reasoning is being carried out - to be able to learn how to perform the problem solving. To achieve transparency we introduce the notions of inferential context and conceptual context. These allow explanations to be composed at various levels of abstraction and from different perspectives and not only exploit a formalisation, but also informal descriptions of the domain knowledge. This facilitates the user’s learning of the domain knowledge and thus his/her ability to co-operate with the system in the problem solving. We integrate techniques from knowledge systems and hypermedia in a system architecture. The architecture deals with formal and informal knowledge. The formal knowledge is used for the formal reasoning, which is based on knowledge systems techniques; the informal knowledge is exploited in this reasoning to generate explanations in different media. The relations between the formal and the informal theory are administered by a metatheory. The metatheory carries out the reasoning in the system and the communication with the user, i.e. the presentation of the explanations and the integration of the user's contribution in the reasoning. The system architecture is transparent, modular and promotes clarity, maintainability and reusability.