Nondeterminism and Guarded Commands

The purpose of this paper is to discuss the relevance of nondeterminism in computer science, with a special emphasis on Dijkstra's guarded commands language.Comment: 34 pages. This is authors' version of Chapter 8 of the book K.R. Apt and C.A.R. Hoare (editors), Edsger Wybe Dijkstra: His Life, Work, and Legacy, volume 45 of ACM Books. ACM/Morgan & Claypool, 202

Cooperation, social norm internalization, and hierarchical societies

Many animal and human societies exhibit hierarchical structures with different degrees of steepness. Some of these societies also show cooperative behavior, where cooperation means working together for a common benefit. However, there is an increasing evidence that rigidly enforced hierarchies lead to a decrease of cooperation in both human and non-human primates. In this work, we address this issue by means of an evolutionary agent-based model that incorporates fights as social interactions governing a dynamic ranking, communal work to produce a public good, and norm internalization, i.e. a process where acting according to a norm becomes a goal in itself. Our model also includes the perception of how much the individual is going to retain from her cooperative behavior in future interactions. The predictions of the model resemble the principal characteristics of human societies. When ranking is unconstrained, we observe a high concentration of agents in low scores, while a few ones climb up the social hierarchy and exploit the rest, with no norm internalization. If ranking is constrained, thus leading to bounded score differences between agents, individual positions in the ranking change more, and the typical structure shows a division of the society in upper and lower classes. In this case, we observe that there is a significant degree of norm internalization, supporting large fractions of the population cooperating in spite of the rank differences. Our main results are robust with respect to the model parameters and to the type of rank constraint. We thus provide a mechanism that can explain how hierarchy arises in initially egalitarian societies while keeping a large degree of cooperation

SCENELAB: Scene Labelling by a Society of Agents; A Distributed Constraint Propagation System

This paper describes SCENELAB, a computer system for labelling line drawings of scenes in simple polyhedral worlds. The key idea behind SCENELAB is to bring together the concept of contraint-based filtering algorithms and the paradigm of societies of cooperating agents. The problem of finding labellings for pictures drawn from blocks world scenes has been taken as a sample application. Clearly, this makes SCENELAB no vision system, but we claim that a system designed along these lines could be part of a real vision system. Following e.g. Alan Mackworth, we argue that constraint exploitation on resp. between various representational levels is a key technique of ‘seeing things'. Furthermore, constraints and constraint propagation neatly fit into the framework of societies of agents, realized by asynchronuously concurrent processing units and message passing mechanisms. SCENELAB, as it is actually running, can be used to specify and solve arbitrary Labelling problems that can be seen as instances of a particular class of simple constraint problems based on finite, pseudo-transitive binary constraints. However, it is felt that the overall approach generalizes to arbitrary constraint problems. Emphasis is given to a mathematical model of the problem and its solution, to be able to specify the reasoning techniques of SCENELAB, and to identify the class of problems it can handle. I tried to shed some Light onto the methodological background of SCENELAB, which seems necessary to judge the achievements and disachievements of the present work. After some introductory chapters on the key concepts involved in SCENELAB, (scene) labelling problems, constraint propagation, and societies of agents, an overview on both the structure and behavior of SCENELAB is given in part B of the paper. In part C, then, an algebraic model is introduced, which serves as a base for discussing several approaches to labelling problems, namely Waltz's original Landmark algorithm, a synchronized parallel solution suggested by Azriel Rosenfeld, and clearly, the present approach. A proof of the correctness of SCENELABs algorithms is included. This proof takes into account the specifities of systems of asynchronously communicating agents where no global state is observable

Impression Formation and Durability in Mediated Communication

Using literature from impression formation and social information processing theory, we examine the impact of communication style on impression formation and durability in a mediated environment. We leverage common writing styles found in workplace emails—emoticons, uppercase, lowercase, typographical errors—to examine how message receivers evaluate senders using these styles. Via a lab experiment with 748 subjects, including undergraduate students, graduate students, and working professionals, we found that impressions were associated with writing style beyond the email content. Receivers perceived senders of emails containing emoticons, errors, or written entirely in uppercase or lowercase as less functionally competent. They also perceived senders as less methodologically competent when emails used emoticons and less politically competent when emails were all lowercase or contained errors. They perceived senders using a neutral writing style as less sociable than senders using emoticons. In contrast to impression durability in face-to-face environments, receivers positively revised impressions when senders changed their style to neutral from any of the non-neutral styles. We attribute this difference to two characteristics of the IT artifact: symbol variety and reprocessability

Concept of a Robust & Training-free Probabilistic System for Real-time Intention Analysis in Teams

Die Arbeit beschäftigt sich mit der Analyse von Teamintentionen in Smart Environments (SE). Die fundamentale Aussage der Arbeit ist, dass die Entwicklung und Integration expliziter Modelle von Nutzeraufgaben einen wichtigen Beitrag zur Entwicklung mobiler und ubiquitärer Softwaresysteme liefern können. Die Arbeit sammelt Beschreibungen von menschlichem Verhalten sowohl in Gruppensituationen als auch Problemlösungssituationen. Sie untersucht, wie SE-Projekte die Aktivitäten eines Nutzers modellieren, und liefert ein Teamintentionsmodell zur Ableitung und Auswahl geplanten Teamaktivitäten mittels der Beobachtung mehrerer Nutzer durch verrauschte und heterogene Sensoren. Dazu wird ein auf hierarchischen dynamischen Bayes’schen Netzen basierender Ansatz gewählt

Introducing the Study of Nordic Cooperation

publishedVersio