THE "POWER" OF TEXT PRODUCTION ACTIVITY IN COLLABORATIVE MODELING : NINE RECOMMENDATIONS TO MAKE A COMPUTER SUPPORTED SITUATION WORK

Language is not a direct translation of a speaker’s or writer’s knowledge or intentions. Various complex processes and strategies are involved in serving the needs of the audience: planning the message, describing some features of a model and not others, organizing an argument, adapting to the knowledge of the reader, meeting linguistic constraints, etc. As a consequence, when communicating about a model, or about knowledge, there is a complex interaction between knowledge and language. In this contribution, we address the question of the role of language in modeling, in the specific case of collaboration over a distance, via electronic exchange of written textual information. What are the problems/dimensions a language user has to deal with when communicating a (mental) model? What is the relationship between the nature of the knowledge to be communicated and linguistic production? What is the relationship between representations and produced text? In what sense can interactive learning systems serve as mediators or as obstacles to these processes

The Competition for Shortest Paths on Sparse Graphs

Optimal paths connecting randomly selected network nodes and fixed routers are studied analytically in the presence of non-linear overlap cost that penalizes congestion. Routing becomes increasingly more difficult as the number of selected nodes increases and exhibits ergodicity breaking in the case of multiple routers. A distributed linearly-scalable routing algorithm is devised. The ground state of such systems reveals non-monotonic complex behaviors in both average path-length and algorithmic convergence, depending on the network topology, and densities of communicating nodes and routers.Comment: 4 pages, 4 figure

A Design Strategy for Deadlock-Free Concurrent Systems

When building concurrent systems, it would be useful to have a collection of reusable processes to perform standard tasks. However, without knowing certain details of the inner workings of these components, one can never be sure that they will not cause deadlock when connected to some particular network. Here we describe a hierarchical method for designing complex networks of communicating processeswhich are deadlock-free.We use this to define a safe and simple method for specifying the communication interface to third party software components. This work is presented using the CSP model of concurrency and the occam2.1 programming language

Modeling Agent Systems with Distributed Transformation Units

AbstractAgent systems have become more and more important in computer science. They allow to implement complex distributed systems composed of communicating autonomous entities. Transformation units constitute a structuring principle for graph transformation systems which split up large sets of rules, but still graphs are transformed as a whole. Recently, distributed transformation units have been introduced as an extension of transformation units to distributed graphs and distributed graph transformation. In this paper it is illustrated how different features of agent systems can be smoothly modeled in a uniform way by distributed graph transformation systems. For this purpose an agent system case study with simple agents communicating via blackboards and message passing is presented

Emergence of Zipf's Law in the Evolution of Communication

Zipf's law seems to be ubiquitous in human languages and appears to be a universal property of complex communicating systems. Following the early proposal made by Zipf concerning the presence of a tension between the efforts of speaker and hearer in a communication system, we introduce evolution by means of a variational approach to the problem based on Kullback's Minimum Discrimination of Information Principle. Therefore, using a formalism fully embedded in the framework of information theory, we demonstrate that Zipf's law is the only expected outcome of an evolving, communicative system under a rigorous definition of the communicative tension described by Zipf.Comment: 7 pages, 2 figure

Ecological conversations and systems thinking

Ideas like ‘ecosystems approach’ or ‘complex adaptive systems’ are often invoked as a panacea for addressing the complex interrelationships and interdependencies associated with issues of climate change. But thinking about nature through ‘systems’ invokes different perspectives, and therefore limitations on our understanding of nature. Systems are maps – conceptual devices for making sense of complex realities and communicating with others about improving those realities. Worthwhile enthusiasm for the study of living systems by complexity scientists and chaos theorists can sometimes distract attention away from this basic premise behind systems thinking. The semiotic idea of confusing the map for the territory is significant particularly when systems are used not only as (inevitably partial) representations of reality, but also as mediating devices for effective ecological conversation with the purpose of generating meaning and value. Fritjof Capra’s ideas on ecoliteracy provides an example of a well-intentioned systems-informed approach towards better informed conversations on environmental issues, but how politically sensitive is this framing device? Building on other systems philosophers - West Churchman, Werner Ulrich and Humberto Maturana - a critical systems approach towards supporting ecological conversations is explored identifying three distinct systems framing – frameworks for understanding (fwU), frameworks for practice (fwP), and frameworks for responsibility(fwR). Whereas fwU can help appreciate the holistic realities of the natural world, fwP can support constructive engagement with multiple perspectives, and fwR reminds us of the limitations of any fwU and fwP whilst keeping attention to improving our framing devices to suite demands of environmental responsibility. Although the gift of framing is one shared by all humans, some frameworks of reference are inevitably given primacy over others, particularly in formulating policy and guiding action. This raises questions about who constructs the framing devices and what legitimacy they have

Communicating complex ecological models to non-scientist end users

Complex computer models are used to predict how ecological systems respond to changing environ- mental conditions or management actions. Communicating these complex models to non-scientists is challenging, but necessary, because decision-makers and other end users need to understand, accept, and use the models and their predictions. Despite the importance of communicating effectively with end users, there is little guidance available as to how this may be achieved. Here, we review the challenges typically encountered by modellers attempting to communicate complex models and their outputs to managers and other non-scientist end users. We discuss the implications of failing to communicate effec- tively in each case. We then suggest a general approach for communicating with non-scientist end users. We detail the specific elements to be communicated using the example of individual-based models, which are widely used in ecology. We demonstrate that despite their complexity, individual-based models have characteristics that can facilitate communication with non-scientists. The approach we propose is based on our experiences and methods used in other fields, but which until now have not been synthesised or made broadly available to ecologists. Our aim is to facilitate the process of communicating with end users of complex models and encourage more modellers to engage in it by providing a structured approach to the communication process. We argue that developing measures of the effectiveness of communication with end users will help increase the impact of complex models in ecology

Decidable Models of Recursive Asynchronous Concurrency

Asynchronously communicating pushdown systems (ACPS) that satisfy the empty-stack constraint (a pushdown process may receive only when its stack is empty) are a popular decidable model for recursive programs with asynchronous atomic procedure calls. We study a relaxation of the empty-stack constraint for ACPS that permits concurrency and communication actions at any stack height, called the shaped stack constraint, thus enabling a larger class of concurrent programs to be modelled. We establish a close connection between ACPS with shaped stacks and a novel extension of Petri nets: Nets with Nested Coloured Tokens (NNCTs). Tokens in NNCTs are of two types: simple and complex. Complex tokens carry an arbitrary number of coloured tokens. The rules of NNCT can synchronise complex and simple tokens, inject coloured tokens into a complex token, and eject all tokens of a specified set of colours to predefined places. We show that the coverability problem for NNCTs is Tower-complete. To our knowledge, NNCT is the first extension of Petri nets, in the class of nets with an infinite set of token types, that has primitive recursive coverability. This result implies Tower-completeness of coverability for ACPS with shaped stacks