System dynamics and microworlds for policymakers

In the past ten years, system dynamics has become more accessible to policymakers and to the academic community. The paper reviews four major developments in the subject that have brought about this change. There have been improvements in the symbols and software used to map and model system structure. New ideas have been adopted from behavioural decision theory which help to transfer policymakers' knowledge into computer models. There have been improvements in methods of simulation analysis that enable modelers and model users to gain better insight into dynamic behaviour. Greater emphasis has been placed on small transparent models, on games and on dialogue between ‘mental models’ and computer simulations. Together these developments allow modelers to create computer-based learning environments (or microworlds) for policymakers to ‘play-with’ their knowledge of business and social systems and to debate policy and strategy change. The paper concludes with some thoughts on future research.     

Bellman Systems with Mean Field Dependent Dynamics

The authors deal with nonlinear elliptic and parabolic systems that are the Bellman like systems associated to stochastic differential games with mean field dependent dynamics. The key novelty of the paper is that they allow heavily mean field dependent dynamics. This in particular leads to a system of PDE’s with critical growth, for which it is rare to have an existence and/or regularity result. In the paper, they introduce a structural assumptions that cover many cases in stochastic differential games with mean field dependent dynamics for which they are able to establish the existence of a weak solution. In addition, the authors present here a completely new method for obtaining the maximum/minimum principles for systems with critical growths, which is a starting point for further existence and also qualitative analysis.     

A decomposition for the space of games with externalities

The main goal of this paper is to present a different perspective than the more ‘traditional’ approaches to study solutions for games with externalities. We provide a direct sum decomposition for the vector space of these games and use the basic representation theory of the symmetric group to study linear symmetric solutions. In our analysis we identify all irreducible subspaces that are relevant to the study of linear symmetric solutions and we then use such decomposition to derive some applications involving characterizations of classes of solutions.     

Simultaneous Sanctioning in Non-Cooperative Games

For use in determining the stability of outcomes in non-cooperative games, an improved definition of simultaneous sanctioning is devised. Conditions such as ‘procrastination’, ‘staying power’ and ‘fear of dire consequences’, which may invoke stability by simultaneous sanctioning in games, are described.     

Supporting strategic conversations: the significance of a quantitative model building process

This paper reports on the use of a quantitative system dynamics simulation model building process that followed on from a ‘soft OR’ strategy making intervention with a top management team. The work was carried out for the Chief Constable and top team of a UK police force. The output of the ‘soft OR’ strategy making process provided the reason for, and so focus of, the simulation model. The focus of the strategic conversation was on exploring the tension between the supply of resources (in this case police officers) and the demands placed on those officers. The project involved a series of strategic conversations with members of the top team that were stimulated through the process of building a system dynamics model. The process was facilitated by two modellers—one focussing on managing the strategic enquiry, while the other considered the implications of the conversation for the construction of the system dynamics model. Through the process of gradually building the system dynamics model, a number of issues and lessons were raised for the development and delivery of effective strategy making and the strategic management of public organisations. In addition there were implications for operational research model building processes, especially when operating at senior levels and within a strategic context.     

Energy modelling platforms for policy and strategy support

The energy field has been dominated by ‘hard’ modelling approaches advocated by researchers from engineering and economics disciplines. The recent trend towards a more liberalised environment moves away from central planning to market-based resource allocation, leading to the creation and use of strategic tools, with much ‘softer’ specifications, in the ‘systems-thinking’ tradition. This paper presents the use of system dynamics in a generalised way, to provide a platform for integrated energy analysis. Issues of modularity and policy evolution are important in the design of the modelling platform to facilitate its use, and reuse. Hence the concept of a platform, rather than a model, has to be implemented in a coherent way if it is to provide sustained value for ongoing support to both government policy and corporate strategy.     

Logic, language games and ludics

Wittgenstein’s language games can be put into a wider service by virtue of elements they share with some contemporary opinions concerning logic and the semantics of computation. I will give two examples: manifestations of language games and their possible variations in logical studies, and their role in some of the recent developments in computer science. It turns out that the current paradigm of computation that Girard termed Ludics bears a striking resemblance to members of language games. Moreover, the kind of interrelations that are emerging could be scrutinised from the viewpoint of logic that virtually necessitates game-theoretic conceptualisations, demonstrating the fact that the meaning of utterances may, in many situations, be understood as Wittgenstein’s language games of ‘showing or telling what one sees’. This provides motivation for the use of games in relation to logic and formal semantics that some commentators have called for. Many of the ideas can be traced to C.S. Peirce, for whom signs were vehicles of strategic communication. The conclusion about Wittgenstein is that the notions of saying and showing converge in his late philosophy.     

Stability and Shapley value for an n-persons fuzzy game

The aim of the paper is to explain new concepts of solutions for n-persons fuzzy games. Precisely, it contains new definitions for ‘core’ and ‘Shapley value’ in the case of the n-persons fuzzy games. The basic mathematical results contained in the paper are these which assert the consistency of the ‘core’ and of the ‘Shapley value’. It is proved that the core (defined in the paper) is consistent for any n-persons fuzzy game and that the Shapley values exists and it is unique for any fuzzy game with proportional values.     

演化博弈与自组织合作

主要研究复杂网络上的演化博弈.首先研究具有社团结构的无标度网络上的演化囚徒困境博弈及Newman-Watts小世界网络中异质性对合作演化的影响.然后考察了在不同合作者和作弊者初始分布配置情况下,不同的初始比例条件对合作水平的影响,且在社会网络上研究了雪堆博弈中的合作演化.进一步地,讨论了网络拓扑和博弈动力学的共同演化问题和网络上演化囚徒困境中的强化学习问题.最后给出了复杂网络上演化博弈论的未来发展方向与应用前景.     

Functional variational principles and coercivity over normed spaces

Using Karlin’s [4] weak game values, a ‘weakly determined’ game is introduced. Conditions for weak determinateness of games and for strict determinateness of weakly determined games are presented. Finally, generalizations of some well-known minimax theorems are derived from these results.     

Systems Analysis and the Computer

The words ‘systems analysis’ are used in at least two senses in the literature. Whilst the general nature of the topic is well understood in the O.R. community, the nature of the term as used by computer scientists is less familiar. In this paper, the nature of systems analysis as it relates to computer-based systems is examined from the point of view that the computer system is an automaton embedded in a human system, and some facets of this are explored. It is concluded that O.R. analysts and computer analysts have things to learn from each other and that this ought to be reflected in their education. The important role played by change in the design of systems is also highlighted, and it is concluded that, whilst the application of techniques developed in the ‘artificial intelligence’ field have considerable relevance to constructing automata able to adapt to change in the environment, study of the human factors affecting the overall systems within which the automata are embedded has an even more important role.     

Evaluating soft OR: some reflections on an apparently ‘unsuccessful’ implementation using a Soft Systems Methodology (SSM) based approach

This paper reflects on a case study in which a soft OR problem structuring approach, based on Soft Systems Methodology (SSM), was used to help in the design of an information system for health service users providing care in the community in a part of the South and West Health Region in the UK. The paper reflects on why an apparently ‘successful’ structuring led to an apparently ‘unsuccessful’ implementation. As part of this reflective process, the paper makes a contribution to the soft OR literature by reviewing some of the approaches taken in the literature to the evaluation of success of problem structuring using soft OR. This review reveals a lack of evaluative criteria, a lack of clarity over the identification of users, and a failure to differentiate criteria associated with ‘structuring’ and ‘implementation’ issues. An evaluative framework is proposed, which is applied retrospectively to the case study.     

Intelligent management systems in operations: a review

Operations management is an area that has recently started to benefit from the use of AI techniques such as expert systems, neural networks and genetic algorithms. These techniques can extend the usefulness of OR modelling and enable new types of decision tasks to be supported by computer-based systems. This paper attempts to review ‘intelligent’ decision support systems and their potential to address some of the problems faced in various areas of operations management. Some useful techniques developed in the field of artificial intelligence are outlined and examples of attempts to use these approaches to support decision making in various areas of operations management are described. Recognising the scale of a complete review of all these areas, emphasis has been given to the most significant and more recent publications.     

Expert Systems for University Admissions

This paper describes the construction of an expert system to help the admissions tutor for a university degree in business and management which receives some 2000 applications for entry each year, using the SAGE shell. What originally began as a ‘demonstrator project’ is shown to be of practical value, in terms of both producing a usable expert system and clarifying and questioning the selection criteria used by the admissions tutor. A particular conclusion emerging from this work which may be relevant to many expert systems applications is that ethical and practical considerations dictated that some questions involving judgement could not be delegated by the admissions tutor to the clerical staff. It thus became necessary to develop two versions of the expert system, one a full ‘admissions-tutor system’, the other a more limited version for day-to-day use.     

Can we have confidence in generic structures?

The system dynamics concept of ‘generic structure’ is dividable into three sub-types. This paper analyses the validity of these three, using both practical and theoretical perspectives. Firstly, a new set of measures is developed for generating validity—‘confidence’—amongst a group using generic structures in a practical modelling situation. It is concluded that different confidence criteria are implicitly employed; there is an argument for trading-off model precision and analytical quality for simplicity and ease of use and future research is needed to combine these ‘process’ and ‘content’ aspects of confidence. From a theoretical stance it is shown that with two of the sub-types a scientific notion of confidence is achievable whereas the third (‘archetypes’) involves merely metaphorical thinking. It is concluded that the theoretical status of archetypes requires further development, whilst ensuring that its benefits are retained.     

Some Methodologies for Community Operational Research

As experience of conducting community OR projects grows and learning accrues, new approaches will be developed offering guidance on how best to proceed in alleviating the problems of community organizations. In the interim, it is sensible to consider which, if any, among the existing OR and systems methodologies might prove useful for this kind of work. In this paper it is argued that there already exist, within what might be described as ‘enhanced OR’, a number of approaches which are suitable for guiding community OR practice. This is demonstrated by outlining some of these methodologies, giving examples of their use with community organizations and showing their particular strengths in the community context. Some conclusions are drawn about the community OR enterprise.     

Structural satisfaction in simple games

A fundamental maxim for any theory of social behavior is that knowledge of the theory should not cause behavior that contradicts the theory's assertions. Although this maxim consistently has been heeded in the theory of noncooperative games, it largely has been ignored in solution theory for cooperative games. Solution theory, the central concern of this paper, seeks to identify a subset of the feasible outcomes of a cooperative game that are ‘stable’ results of competition among participants, each of whom attempts to bring about an outcome he favors, rather than to prescribe ‘fair’ outcomes that accord with a standard of equity. We show that learning by participants about the solution theory can cause the outcomes identified as stable by certain solution concepts to become unstable, and discover that an important distinction in this regard is whether the solution concept requires each element of the solution set to defend itself against alternatives rather than relying on other elements for its defense. Finally, we develop a concept of ‘solid’ solutions which have a special claim for stability.The unifying theme of this paper concerns the sense in which certain outcomes of a cooperative game may be regarded as stable, and the extent to which this stability requires that the players are ignorant of the theory. Although the issues raised here have implications for the theory of cooperative games in general, Section 1 establishes the focus of the analysis on collective decision games. Section 2 develops some general perspectives on solution theory which are used in Sections 3 and 4 to evaluate the Condorcet solution, the core, the robust proposals set, von Neumann- Morgenstern solutions and competitive solutions. Section 5 presents the concept of a solid solution and relates this idea to the solution concepts reviewed earlier. We demonstrate that in general a solution concept has a strong claim to stability only if it is solid. Finally, Section 6 concludes by indicating that the basic argument also can be applied to Aumann and Maschler's bargaining sets and, more generally, to solution theory for any cooperative game.     

Games with guaranteed scores and waiting moves

Combinatorial scoring games, with the property ‘extra pass moves for a player will do him no harm’, are characterized. The characterization involves an order embedding of Conway’s normal play games, and we call our class the universe of Guaranteed scoring games. Also, we give a theorem for comparing guaranteed games with scores (numbers) which extends Ettinger’s work on Dicot scoring games.     

Bidders and dispenser: manipulative hypergames in a multinational context

The object of this paper is to present an introduction to the basic ideas of Hypergame Analysis, and to illustrate these by building some models of a particular type of situation.Hypergame Analysis is an extension of the Game-theoretic framework, the purpose of which is to enable one to model situations in which the various parties are not well-informed of each other's preferences and strategies. we take as a basic structure not a single game, but a linked set of ‘perceived’ games: this, in essence, is what constitutes a Hypergame. Misperceptions may arise accidentally or be deliberately induced. Thus, a player may be acting ‘rationally’ relative to the game he perceives, but this game itself may have been ‘set up’ to suit the interests of some other party.The technique is used to explore situations in which several parties (the ‘bidders’) negotiate competitively with another (the ‘dispenser’) who is able to accept whichever bidder's offer is most advantageous to him. In particular, the ability of the dispenser to ‘play off’ one bidder against another is examined. This is related to an account of the siting of new plant by a Multi-National Corporation. Some general implications are suggested: especially, it is argued that to have a reasonable chance of producing adequate forecasts in such difficult situations, modelling techniques must embody at least this degree of conceptual complexity.     

Helping Managers Manage

Do conventional management accounts help managers manage? This paper argues that the answer to this question is ‘No’, primarily because conventionally prepared budgets are not accepted by managers as valid measures of performance as a result of either forecasting errors in the data used in the original budget or weaknesses in the simulation algorithms inherent in the budget. The paper then suggests that management accounts can be made more meaningful by incorporating within the management accounting system a ‘resource management system’, the basis of which is a powerful simulation model.