Typically, studies of ubiquitous computing environments focus on context-aware assistance for activities in a closed domain, such as guide systems in museums, and ignore ways of coordinating services between two different service environments. However, it is important to provide them with personalized assistance services that seamlessly coordinate two service environments for the users who move from an open ubiquitous computing environment to other. This study specifically examines seamless personalized services for mobile users and presents a framework of role-based agent coordination to provide services for them. In that framework, personal agents, which are always with the users, play roles assigned by a role manager agent when they participate in new environments. We show a new agent coordination protocol, which is an extension of the contract-net protocol, to perform context-aware role assignments to realize those services.

This paper proposes an approach to enhance dialogue capabilities between humans and the computer. In order for a computer system to sustain a natural conversation without constraining the topic, it must be able to generate a natural response to a wide variety of topics. In particular, a good general-purpose dialogue system must be able to infer the user's intention from an utterance and be able to respond to it appropriately. A case-based dialogue system could provide an approach to solve these problems because it can work as an empirical language learner, and can become a better hearer and speaker for the human user as the case database becomes larger during dialogues. The goal of this research is to design an efficient case-base for a dialogue system, which contains dialogues between humans or between a human and a computer. We define "dialogue act", which is a key to finding the user's intention and for searching appropriate cases in the case-base. We describe how to extract useful knowledge from example dialogues and how to choose an optimal case to generate an appropriate response.