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An organization is a collection of agents that interact and produce some form of output. Formal organizations - such as corporations and governments - are typically constructed for an explicit purpose though this purpose needn't be shared by all organizational members. An entrepreneur who creates a firm may do so in order to generate personal wealth but the worker she hires may have very different goals. As opposed to more amorphous collections of agents such as friendship networks and societies at large, organizations have a formal structure to them (though informal structures typically emerge as well) with the prototypical example being a corporation's organizational chart. This structure serves to define lines of communication and the distribution of decision-making. Organizations are also distinguished by their well-defined boundaries as reflected in a clear delineation as to who is and who is not a member. This boundary serves to make organizations a natural unit of selection; for example, corporations are formed and liquidated though they can also morph into something different through activities like mergers.

Yip Kin Fung. ; Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. ; Includes bibliographical references (leaves 101-104). ; Abstracts in English and Chinese. ; Chapter 1 --- Introduction --- p.1 ; Chapter 2 --- The Distribution of Fluctuations in Financial Data --- p.5 ; Chapter 2.1 --- Empirical Statistics --- p.5 ; Chapter 2.2 --- Data analyzed --- p.8 ; Chapter 2.3 --- Levy Distribution --- p.10 ; Chapter 2.4 --- Returns Distribution and Scaling Properties --- p.12 ; Chapter 2.5 --- Volatility Clustering --- p.19 ; Chapter 2.6 --- Conclusion --- p.21 ; Chapter 3 --- Models of Herd behaviour in Financial Markets --- p.22 ; Chapter 3.1 --- Cont and Bouchaud's model --- p.22 ; Chapter 3.2 --- The Model of Egiuluz and Zimmerman --- p.24 ; Chapter 3.3 --- EZ Model with Size-Dependent Dissociation Rates --- p.28 ; Chapter 3.4 --- Democratic and Dictatorship Self-Organized Model --- p.31 ; Chapter 3.5 --- Effect of Size-Dependent Fragmentation and Coagulation Prob- abilities --- p.33 ; Chapter 3.6 --- Extensions of EZ model --- p.35 ; Chapter 3.7 --- Conclusion --- p.39 ; Chapter 4 --- Review on the Minority Game(MG) --- p.42 ; Chapter 4.1 --- The Model and Results --- p.42 ; Chapter 4.2 --- Crowd-anticrowd Theory and Phase Transition --- p.46 ; Chapter 4.3 --- Market Efficiency --- p.48 ; Chapter 5 --- MG with biased strategy pool --- p.52 ; Chapter 5.1 --- The Model --- p.53 ; Chapter 5.2 --- Numerical Results and Discussion --- p.53 ; Chapter 5.3 --- Theory: MG with Biased Strategy Pool --- p.61 ; Chapter 5.4 --- Conclusion --- p.69 ; Chapter 6 --- MG with Randomly Participating Agents --- p.71 ; Chapter 6.1 --- The Model with One RPA --- p.71 ; Chapter 6.2 --- Results for q = 0.5 --- p.72 ; Chapter 6.3 --- Inefficiency and Success Rate --- p.76 ; Chapter 6.4 --- Results for q ≠ 0.5 --- p.82 ; Chapter 6.5 --- Many RPAs --- p.85 ; Chapter 6.6 --- Conclusion --- p.86 ; Chapter 7 --- A Model on Coupled Minority Games --- p.88 ; Chapter 7.1 --- The Model --- p.89 ; Chapter 7.2 --- Results and Discussion。 --- ...

Agent-based simulation models have a promising future in the social sciences, from political science to anthropology, economics, and sociology. To realize their full scientific potential, however, these models must address a set of key problems, such as the number of interacting agents and their geometry, network topology, time calibration, phenomenological calibration, structural stability, power laws, and other substantive and methodological issues. This paper discusses and highlights these problems and outlines some solutions.

Agent-based modeling promises to overcome the reification of actors. Whereas this common, but limiting, assumption makes a lot of sense during periods characterized by stable actor boundaries, other historical junctures, such as the end of the Cold War, exhibit far-reaching and swift transformations of actors' spatial and organizational existence. Moreover, because actors cannot be assumed to remain constant in the long run, analysis of macrohistorical processes virtually always requires "sociational" endogenization. This paper presents a series of computational models, implemented with the software package REPAST, which trace complex macrohistorical transformations of actors be they hierarchically organized as relational networks or as collections of symbolic categories. With respect to the former, dynamic networks featuring emergent compound actors with agent compartments represented in a spatial grid capture organizational domination of the territorial state. In addition, models of "tagged" social processes allows the analyst to show how democratic states predicate their behavior on categorical traits. Finally, categorical schemata that select out politically relevant cultural traits in ethnic landscapes formalize a constructivist notion of national identity in conformance with the qualitative literature on nationalism. This "finite-agent method", representing both states and nations as higher-level structures superimposed on a lower-level grid of primitive agents or cultural traits, avoids reification of agency. Furthermore, it opens the door to explicit analysis of entity processes, such as the integration and disintegration of actors as well as boundary transformations.

While neorealism and world-system theory both claim to be "structural" theories of international relations, they embody very different understandings of system structure and structural explanation. Neorealists conceptualize system structures in individualist terms as constraining the choices of preexisting state agents, whereas world-system theorists conceptualize system structures in structuralist terms as generating state agents themselves. These differences stem from what are, in some respects, fundamentally opposed solutions to the "agent-structure" or "micromacro" problem. This opposition, however, itself reflects a deeper failure of each theory to recognize the mutually constitutive nature of human agents and system structures—a failure which leads to deep-seated inadequacies in their respective explanations of state action. An alternative solution to the agent-structure problem, adapted from "structuration theory" in sociology, can overcome these inadequacies by avoiding both the reduction of system structures to state actors in neorealism and their reification in world-system theory. Structuration theory requires a philosophical basis in scientific realism, arguably the "new orthodoxy" in the philosophy of natural science, but as yet largely unrecognized by political scientists. The scientific realist/structuration approach generates an agenda for "structural-historical" research into the properties and dispositions of both state actors and the system structures in which they are embedded.

Neorealism and world-system theory both claim to be 'structural' theories of international relations, yet they embody very different understandings of system structure and structural explanation. These differences stem from fundamentally opposed solutions to the 'agent-structure' or 'micro-macro' problem. An alternative solution to the agent-structure problem, adapted from 'structuration theory' in sociology, can overcome these inadequacies. Discusses its approach. (Abstract amended)