Lars Hallnäs

Slow Technology – Designing for Reflection

Abstract: As computers are increasingly woven into the fabric of everyday life, interaction design may have to change – from creating only fast and efficient tools to be used during a limited time in specific situations, to creating technology that surrounds us and therefore is a part of our activities for long periods of time. We present slow technology: a design agenda for technology aimed at reflection and moments of mental rest rather than efficiency in performance. The aim of this paper is to develop a design philosophy for slow technology, to discuss general design principles and to revisit some basic issues in interaction design from a more philosophical point of view. We discuss examples of soniture and informative art as instances of slow technology and as examples of how the design principles can be applied in practice.

Informative art: using amplified artworks as information displays

Informative art is computer augmented, or amplified, works of art that not only are aesthetical objects but also information displays, in as much as they dynamically reflect information about their environment. Informative art can be seen as a kind of slow technology, i.e. a technology that promotes moments of concentration and reflection. Our aim is to present the design space of informative art. We do so by discussing its properties and possibilities in relation to work on information visualisation, novel information display strategies, as well as art. A number of examples based on different kinds of mapping relations between information and the properties of the composition of an artwork are described.

Partial inductive definitions

Abstract An attempt to consider partial definitions of semantically oriented data types will be described. We will in a certain sense think of such data types as inductively defined. A class of inductive definitions will be interpreted as partial definitions: partial inductive definitions . The presentation of such a definition is in itself elementary and the true complexity of the definition will show itself in questions concerning the isolation of totally defined objects. It is the same situation as in the case of partial recursive functions. The basic aim is to investigate the possibility to give direct inductive definitions of semantical notions exploring, so to speak, the structure of the given notion rather than to think of such notions as indirectly presented by a formal system or given by a definition, together with a proof of its correctness, in terms of recursion on some well-founded structure.

Extensions of Logic Programming

What do you do to start reading extensions of logic programming? Searching the book that you love to read first or find an interesting book that will make you want to read? Everybody has difference with their reason of reading a book. Actuary, reading habit must be from earlier. Many people may be love to read, but not a book. Its not fault. Someone will be bored to open the thick book with small words to read. In more, this is the real condition. So do happen probably with this extensions of logic programming.

A Proof-Theoretic Approach to Logic Programming. I. Clauses as Rules

In this paper definite Horn clause programs are investigated within a proof-theoreti c framework; program clauses being considered rules of a formal system. Based on this approach, the soundness and completeness of SLD-resolutio n is established by purely proof-theoretic methods. Extended Horn clauses are defined as rules of higher levels and related to an approach based on implication formulae in the bodies of clauses. In a further extension, which is treated in Part II of this series, program clauses are viewed as clauses in inductive definitions of atoms, justifying an additional inference schema: a reflection principle that roughly corresponds to interpreting the program clauses as introduction rules in the sense of natural deduction. The evaluation procedures for queries with respect to the defined extensions of definite Horn clause programs are shown to be sound and complete. The sequent calculus with the general elimination schema even permits the

Textile displays: using textiles to investigate computational technology as design material

As we face an increasingly heterogeneous collection of computational devices, there is a need to develop a general approach to what it is that we design as we create computational things. One such basic approach is to consider computational technology to be a design material. In the present paper, we describe how a traditional material --- textiles --- can be used to investigate aspects of the expressiveness and aesthetics of computational technology as design material. As an example of this approach, we use an experimental design project made for an art museum. We describe a series of conceptual sketches of how textile artefacts can be used to re-interpret elementary acts of information technology use and the experiences from working with the final installation of one of them. Finally, we discuss properties of textiles and computational technology, such as expressions related to vagueness, unpredictability and slowness.

On the Proof-theoretic Foundation of General Definition Theory

A general definition theory should serve as a foundation for the mathematical study of definitional structures. The central notion of such a theory is a precise explication of the intuitively given notion of a definitional structure. The purpose of this paper is to discuss the proof theory of partial inductive definitions as a foundation for this kind of a more general definition theory. Among the examples discussed is a suggestion for a more abstract definition of lambda-terms (derivations in natural deduction) that could provide a basis for a more systematic definitional approach to general proof theory.

On the syntax of infinite objects: an extension of Martin-Löf's theory of expressions

On basis of Churchs simply typed h-calculus Martin-Lhf has developed a theory of expressions as a general framework for notations in his type theory. (See [11]). We may think of this theory as exploiting the canonical syntax of notations for finite objects. Below we will give an outline of a proposal of how one possible could extend Martin-Lhfs theory of expressions to a theory exploiting the syntax of notations for possibly infinite objects. Basically this is done by incorporating as a primitive operation what is usually referred to as naive substitution within the theory substitution as a defined operation is usually the basic tool in expressing the semantics of operators that introduce infinite objects: r c(b, x) = x)/x) (See [9], [10]). Incorporating these things within the syntax itself will raise questions concerning the role of bound variables and the purely compositional understanding of syntactic items, In the present treatment of these things bound variables are not regarded as placehoIders, but rather as selected objects in a given context and the notion of a closed term is not compositionally based, (Of course this affects the logic associated with the notion of a closed term as a proof, but that is another story.) Given a variable x and an expression E we may abstract x in E:

On the Proof-Theoretic Foundations of Set Theory

In this paper we discuss a proof-theoretic foundation of set theory that focusses on set definitions in an open type free framework. The idea to make Cantor’s informal definition of the notion of a set more precise by saying that any given property defines a set seems to be in conflict with ordinary modes of reasoning. There is to some extent a confusion here between extensional perspectives (sets as collections of objects) and intensional perspectives (set theoretic definitions) that the central paradoxes build on. The solutions offered by Zermelo-Fraenkel set theories, von Neumann-Bernays set-class theories and type theories follow the strategy of retirement behind more or less safe boundaries. What if we revisit the original idea without making strong assumptions on closure properties of the theoretical notion of a set? That is, take the basic definitions for what they are without confusing the borders between intensional and extensional perspectives.

Design process: design rationale the Affective Diary

This note is a critical review of some aspects of the design case presented in Reflecting on the Design Process of the Affective Diary, Proceedings of NordiCHI2008.