recent advances in web technology, interface design, and specification. Our effort to improve the usability of such systems has led us into algebraic semiotics, while our effort to develop better formal methods for distributed concurrent systems has led us into hidden algebra and fuzzy logic. This paper discusses the Tatami system design, especially its software architecture, and its user interface principles. New work in the latter area includes an extension of algebraic semiotics to dynamic multimedia interfaces, and integrating Gibsonian affordances with algebraic semiotics. 1

The Tatami project is building a system to support software engineering over the internet, exploiting recent advances in web technology, interface design, and specification. Our effort to improve the usability of such systems led us into algebraic semiotics, while our effort to develop better formal methods for distributed concurrent systems led us into hidden algebra. We discuss the Tatami system design, especially user interface issues, and sketch an extension of algebraic semiotics for interface dynamics. 1 Introduction The Tatami project has pursued three main goals: 1. explore novel multimedia interface design principles, for easing the use of complex interactive systems; 2. build and use a generic distributed environment for cooperative work; and 3. verify distributed concurrent software. We discuss these goals in turn. The first is motivated by the difficulties many practicing engineers have with formal methods tools. We have taken theorem provers as a typically difficult c...

Introduction Agents are increasingly upon us. Although opposition is rare, \intelligent agents" have been attacked for user interface problems, and on larger social issues. Agent supporters have countered these arguments and raised doubts about alternative technologies. We place this in historical, social, and ethical contexts, noting the cyclic nature of such debates. One conclusion is that many problems with arti cial agents arise from a poor understanding of social aspects of human agents. 2. Historical Perspectives The history of technology has seen many movements call for human-like systems, and use anthropomorphic terminology to generate understanding and support. Such movements often make excessive claims, perhaps misled by their own rhetoric or their (sometimes impressive) partial success. This raises unrealistic expectations, which often leads to disappointment, which is surprisingly often followed by rebirth with similar goals, and somewhat improved terminology and techno