Optimal modeling for complex system design

The article begins with a brief introduction to the theory describing optimal data compression systems and their performance. A brief outline is then given of a representative algorithm that employs these lessons for optimal data compression system design. The implications of rate-distortion theory for practical data compression system design is then described, followed by a description of the tensions between theoretical optimality and system practicality and a discussion of common tools used in current algorithms to resolve these tensions. Next, the generalization of rate-distortion principles to the design of optimal collections of models is presented. The discussion focuses initially on data compression systems, but later widens to describe how rate-distortion theory principles generalize to model design for a wide variety of modeling applications. The article ends with a discussion of the performance benefits to be achieved using the multiple-model design algorithms

Governance of a complex system: water

This paper sets out a complex adaptive systems view of water governance. Overview Fresh water is a life - enabling resource as well as the source of spiritual, social and economic wellbeing and development. It is continuously renewed by the Earth’s natural recycling systems using heat from the sun to evaporate and purify, and then rain to replenish supplies. For thousands of years people have benefited from these systems with little concern for their ability to keep up with human population and economic development. Rapid increases in population and economic activity have brought concern for how these systems interact with human social and economic systems to centre stage this century in the guise of a focus on water governance. What do we mean by governance and how might we better understand our water governance systems to ensure their ongoing sustainability? This paper sets out a complex adaptive systems view of water governance. It draws on the academic literature on effective governance of complex systems and effective water governance to identify some principles for use in water governance in New Zealand. It illustrates aspects of emerging water governance practice with some examples from New Zealand which have employed a multi-actor, collaborative governance approach. The paper concludes with some implications for the future evolution of effective water governance in New Zealand. Collaborative governance processes are relatively unfamiliar to New Zealand citizens, politicians and other policy actors which makes it more important that we study and learn from early examples of the use of this mode of governance

A Process-Oriented Architecture for Complex System Modelling

A fine-grained massively-parallel process-oriented model of platelets (potentially artificial) within a blood vessel is presented. This is a CSP inspired design, expressed and implemented using the occam-pi language. It is part of the TUNA pilot study on nanite assemblers at the universities of York, Surrey and Kent. The aim for this model is to engineer emergent behaviour from the platelets, such that they respond to a wound in the blood vessel wall in a way similar to that found in the human body -- i.e. the formation of clots to stem blood flow from the wound and facilitate healing. An architecture for a three dimensional model (relying strongly on the dynamic and mobile capabilities of occam-pi) is given, along with mechanisms for visualisation and interaction. The biological accuracy of the current model is very approximate. However, its process-oriented nature enables simple refinement (through the addition of processes modelling different stimulants/inhibitors of the clotting reaction, different platelet types and other participating organelles) to greater and greater realism. Even with the current system, simple experiments are possible and have scientific interest (e.g. the effect of platelet density on the success of the clotting mechanism in stemming blood flow: too high or too low and the process fails). General principles for the design of large and complex system models are drawn. The described case study runs to millions of processes engaged in ever-changing communication topologies. It is free from deadlock, livelock, race hazards and starvation em by design, employing a small set of synchronisation patterns for which we have proven safety theorems

Economic Development and Inequality: a complex system analysis

By borrowing methods from complex system analysis, in this paper we analyze the features of the complex relationship that links the development and the industrialization of a country to economic inequality. In order to do this, we identify industrialization as a combination of a monetary index, the GDP per capita, and a recently introduced measure of the complexity of an economy, the Fitness. At first we explore these relations on a global scale over the time period 1990--2008 focusing on two different dimensions of inequality: the capital share of income and a Theil measure of wage inequality. In both cases, the movement of inequality follows a pattern similar to the one theorized by Kuznets in the fifties. We then narrow down the object of study ad we concentrate on wage inequality within the United States. By employing data on wages and employment on the approximately 3100 US counties for the time interval 1990--2014, we generalize the Fitness-Complexity algorithm for counties and NAICS sectors, and we investigate wage inequality between industrial sectors within counties. At this scale, in the early nineties we recover a behavior similar to the global one. While, in more recent years, we uncover a trend reversal: wage inequality monotonically increases as industrialization levels grow. Hence at a county level, at net of the social and institutional factors that differ among countries, we not only observe an upturn in inequality but also a change in the structure of the relation between wage inequality and development