Markovian assignment rules

We analyze dynamic assignment problems where agents successively receive different objects (positions, offices, etc.). A finite set of n vertically differentiated indivisible objects are assigned to n agents who live n periods. At each period, a new agent enters society, and the oldest agent retires, leaving his object to be reassigned. We define independent assignment rules (where the assignment of an object to an agent is independent of the way other objects are allocated to other agents), efficient assignment rules (where there does not exist another assignment rule with larger expected surplus), and fair assignment rules (where agents experiencing the same circumstances have identical histories in the long run). When agents are homogenous, we characterize efficient, independent and fair rules as generalizations of the seniority rule. When agents draw their types at random, we prove that independence and efficiency are incompatible, and that efficient and fair rules only exist when there are two types of agents. We characterize two simple rules (type-rank and type-seniority) which satisfy both efficiency and fairness criteria in dichotomous settings.     

People with disability and new disaster communications: access and the social media mash-up

This article explores how a lack of access to increasingly complex and overlapping digital communications platforms in times of disaster for people with disabilities has the potential to make already life-threatening situations considerably more dangerous. As we are increasingly coming to rely on a social media mash-up of digital platforms to assist in communications during disaster situations, the issue of accessibility for people with disabilities is as dire as if it was high ground during a tsunami or transport during a typhoon. The contemporary social media environment is characterised by a complex and overlapping network of complementary platforms, populated by user-generated content, where people communicate and exchange ideas. In this environment, YouTube videos are posted to Facebook and embedded in blogs, and Twitter is used to link to these other sites and is itself embedded in other platforms. These networks are increasingly supplementing and supplanting more traditional communication platforms, such as the television and radio, particularly in times of disaster. The concern of this paper is that the elements from which this mash-up of communications channels is made are not always accessible to people with disabilities. This evolving network of social media-based communication exposes the limits of existing Internet-based universal design.     

Agent Rationality Behind Network Formation

We search for agent behavior rules which lead to the emergence of social networks that exhibit empirically observed phenomena: small-world property, scale-free degree distribution and stability in time. We assume that agents form and sever links using a cost-benefit analysis. Agents receive benefit from own links and from links that their friends form. On the other hand, link formation, deletion and keeping is costly. We find that a simple model structure which relies only on convex cost of link upkeep leads to stable networks which exhibit the small-world property.     

The division problem with voluntary participation

The division problem consists of allocating a given amount of a homogeneous and perfectly divisible good among a group of agents with single-peaked preferences on the set of their potential shares. A rule proposes a vector of shares for each division problem. The literature has implicitly assumed that agents will find acceptable any share they are assigned to. In this article we consider the division problem when agents’ participation is voluntary. Each agent has an idiosyncratic interval of acceptable shares where his preferences are single-peaked. A rule has to propose to each agent either to not participate or an acceptable share because otherwise he would opt out and this would require to reassign some of the remaining agents’ shares. We study a subclass of efficient and consistent rules and characterize extensions of the uniform rule that deal explicitly with agents’ voluntary participation.     

Equivalence of Nash implementability and robust implementability with incomplete information

This paper is concerned with the design of robust mechanisms which are applicable to a wide class of possible information structures of agents. We examine a society consisting of several groups such that (i) there are at least three agents in each group; and (ii) each agent knows the preferences of the agents in his group but has incomplete information about the preferences of the agents outside his group. We show that for a large class of information structures, a social choice set (SCS) is implementable for each possible information structure if and only if it is Nash implementable. In other words, the class of robustly implementable SCS's is identical to the class of implementable SCS's in the complete information setting.This paper is a substantially revised version of a chapter of my dissertation submitted to the University of Rochester (Yamato [25]). I thank Professor William Thomson for his invaluable advice and suggestions. Detailed comments and suggestions of an anonymous referee were very helpful for further revision of the paper. I also acknowledge comments from Professors Randall Calvert, Luis Corchon, Glenn MacDonald, Eric Maskin, Lionel McKenzie, Ryo-Ichi Nagahisa, Koji Okuguchi, Ignacio Ortuño-Ortin, Tatsuyoshi Saijo, Ken-Ichi Shimomura, Tomas Sjöström, Yoshikatsu Tatamitani, and seminar participants at Harvard University, the 1992 Meeting of Kobe Summer Seminar in Economics of Organization and Game Theory, Tokyo Metropolitan University, and Toyama University. This work was supported in part by the Ministry of Education in Japan, the Nomura Foundation for the Social Sciences, and the Tokyo Center for Economic Research.     

Social creativity as a function of agent cognition and network properties: A computer model

Inventions – concepts, devices, procedures – are often created by networks of interacting agents in which the agents can be individuals (as in a scientific discipline) or they can themselves be collectives (as in firms interacting in a market). Different collectives create and invent at different rates. It is plausible that the rate of invention is jointly determined by properties of the agents (e.g., their cognitive capacity) and by properties of the network of interactions (e.g., the density of the communication links), but little is known about such two-level interactions. We present an agent-based model of social creativity in which the individual agent captures key features of the human cognitive architecture derived from cognitive psychology, and the interactions are modeled by agents exchanging partial results of their symbolic processing of task information. We investigated the effect of agent and network properties on rates of invention and diffusion in the network via systematic parameter variations. Simulation runs show, among other results, that (a) the simulation exhibits network effects, i.e., the model captures the beneficial effect of collaboration; (b) the density of connections produces diminishing returns in term of the benefits on the invention rate; and (c) limits on the cognitive capacity of the individual agents have the counterintuitive consequence of focusing their efforts. Limitations and relations to other computer simulation models of creative collectives are discussed.     

The Separability Principle in Economies with Single-Peaked Preferences

We investigate the implications of the “separability principle” for the class of problems allocating an infinitely divisible commodity among a group of agents with single-peaked preferences. The separability principle requires that for two problems with the same population, but possibly different social endowments, in which the preferences of agents may change, if there is a subgroup of agents whose preferences are the same and the total amounts awarded to them are the same, then the amount awarded to each agent in the subgroup should be the same. First, we investigate the logical relations between separability and other axioms. As it turns out, consistency implies separability. Then, we present characterizations of the uniform rule on the basis of separability and also on the basis of other axioms.     

New variable-population paradoxes for resource allocation

We identify previously unnoticed ways in which agents can strategically distort allocation rules, by affecting the set of “active” agents. (i) An agent withdraws with his endowment. (ii) He gives control of his endowment to someone else and withdraws. (iii) He invites someone in and let him use some of his endowment. (iv) He pre-delivers to some other agent the net trade that the rule would assign to that second agent if that second agent had participated. In (i) and (ii), he and his co-conspirator may end up controlling resources that allow them to reach higher welfare levels than they otherwise would. In (iii) and (iv), he may end up with a bundle that he prefers to the one he would have been assigned had he not engaged in the manipulation. We show that (i) the Walrasian rule is not “withdrawing-proof”, nor “endowments-merging-proof, nor “endowments-splitting-proof”, but that it is “pre-delivery-proof”, and that (ii) canonical selections from the egalitarian-equivalence-in-trades solutions satisfy none of the properties.     

Balanced consistency and balanced cost reduction for sequencing problems

We investigate the implications of balanced consistency and balanced cost reduction in the context of sequencing problems. Balanced consistency requires that the effect on the payoff from the departure of one agent to another agent should be equal between any two agents. On the other hand, balanced cost reduction requires that if one agent leaves a problem, then the total payoffs of the remaining agents should be affected by the amount previously assigned to the leaving agent. We show that the minimal transfer rule is the only rule satisfying efficiency and Pareto indifference together with either one of our two main axioms, balanced consistency and balanced cost reduction.     

Communication networks and their role in cooperative games

We consider cooperative games subordinated to communication networks, which indicate those players able to communicate directly as well as the strengths of their relationships. We develop an index of a player's ability to communicate with others and we also create a new game whose solution reflects this ability in conjunction with the economic capabilities described by the original game.     

The Networked Household

The authors argue that individuals, rather than family solidarities, have become the primary unit of household connectivity. Many households do not operate as traditional densely knit groups but as more sparsely knit social networks where individuals juggle their somewhat separate agendas and schedules. At a time when many people enact multiple, individual roles at home, in the community and at work, the authors ask: how do adult household members communicate with each other? How do adult household members use information and communication technologies (ICTs) to organize, communicate and coordinate their leisure and social behavior both inside and outside the home? Interviews and surveys conducted in 2004-2005 in the Toronto, Canada area of East York show that households remain connected - but as networks rather than solidary groups. The authors describe how networked individuals bridge their relationships and connect with each other inside and outside the home. ICTs have afforded household members the ability to go about on their separate ways while staying more connected - by mobile phone, email and IM - as well as by traditional landlines. In such ways, rather than pulling families apart, ICTs often facilitate communication, kinship and functional integration.     

Cohesiveness and goals in agency networks: Explaining conflict and cooperation

This paper examines principal and agent networks. We focus on networks because business research has placed far greater emphasis on the agency problem at the individual level. Our interest is in exploring the agency relationship at the group or network level. There are many variables at the group or network level which are absent when analyzing agency relationships at the individual level. Traditional theories of finance and economics do not adequately address or explain a host of behaviors that are inherent in human interactions that constitute organizational life. We include a sociological or behavioral approach in understanding this complex relationship. Using cohesiveness and shared goals as antecedents, we develop a theoretical model that predicts a range of relationship outcomes between principals and agents, as well as their impact on organizational goals. We explain that a range of relationships – including conflict, domination, exploitation, collaboration, and cooperation – is possible when networks of principals and agents interact.We argue that the social context is a key determinant of the relationship between actors in a network, and it has an important role in impacting cohesiveness and goal mutuality. The degree of cohesiveness within and between networks, and the extent to which goals are shared or are in conflict are the principal predictor variables we examine. We posit that cohesiveness and shared goals are necessary and sufficient conditions for agency problems between networks to be alleviated. Both necessary and sufficient conditions need to be met in order to overcome the problems of agency. The relationships we examine through the model include cooperation, collaboration, domination, opportunism, exploitation, and conflict. We present a number of propositions that theorize on the nature of the agency relationship and their impact on organizational goals. Implications for research and practice are also discussed.     

INTELLIGENT AGENCY

We are facing a new technological assemblage, networks of communication and information technology which mediate our lives in new ways. Within the discourses surrounding these new networks, amidst promises of unlimited agency, power and control, sits the key figure of the intelligent agent. An intelligent agent is a software program that would act in one's place in cyberspace, as a digital butler of sorts. Drawing on the actor-network theory of Bruno Latour and others, and the philosophy of Gilles Deleuze and Felix Guattari, this article analyses the politics and possibilities of intelligent agents. It focuses on prominent themes in the discourse about intelligent agents, such as libertarianism, consumerism, trust, and the abandonment of the body into a digital realm. Ultimately, the article argues, we need to view technologies, and agency, as embodied and contextualized, and abandon the modernist separation of humans and technologies.     

The replacement principle for the provision of multiple public goods on tree networks

This article considers the provision of two public goods on tree networks where each agent has a single-peaked preference. We show that if there are at least four agents, then no social choice rule exists that satisfies efficiency and replacement-domination. In fact, these properties are incompatible, even if agents’ preferences are restricted to a smaller domain of symmetric single-peaked preferences. However, for rules on an interval, we prove that Miyagawa’s (Soc Choice Welf 18:527–541, 2001) characterization that only the left-peaks rule and the right-peaks rule satisfy both of these properties also holds on the domain of symmetric single-peaked preferences. Moreover, if agents’ peak locations are restricted to either the nodes or the endpoints of trees, rules exist on a subclass of trees. We provide a characterization of a family of such rules for this tree subclass.     

Networks of international public relations production: The case of Latin American organizations’ connections to U.S. agents

Traditionally, international public relations studies have assumed that a foreign organization, namely a foreign government, is the primary influence on how its home country is portrayed to audiences abroad. This study challenges such assumption of independence by revealing how foreign organizations are connected in ways previous works have not considered. Using Foreign Agents Registration Act data, we reveal the direct and indirect connections that form when foreign organizations hire U.S. agencies to produce their international public relations work. Our network analysis of foreign organizations from Latin American and their U.S. agents documents the network structures that emerge for each country and identifies the types of organizations that are positioned advantageously in the networks. We use these findings to theorize how foreign organizations’ connections and their key positions in networks may influence the production of international public relations efforts for their home country. We at a macro-level, public relations effects depend on the structure of the networks, the overlapping sites where communication content is produced, and who is positioned as key players in the production networks.     

Natural implementation in public goods economies

In this paper, we identify necessary and sufficient conditions for social choice correspondences to be Nash implemented by “natural” mechanisms in economies with arbitrary numbers of private and public goods. We find that when there exist only one public good and an arbitrary number of private goods, the Lindahl correspondence is implementable by a natural quantity mechanism in which each agent announces his own consumption bundle of private goods and input vectors for public goods. However, regardless of the numbers of private and public goods, the Pareto correspondence is not implementable even by any natural price ⁿ -quantity mechanism in which each agent reports a price vector of private goods and all agents’ personalized price vectors of public goods, in addition to his own consumption bundle of private goods and input vectors for public goods.     

Homophily and Contagion Are Generically Confounded in Observational Social Network Studies

The authors consider processes on social networks that can potentially involve three factors: homophily, or the formation of social ties due to matching individual traits; social contagion, also known as social influence; and the causal effect of an individual's covariates on his or her behavior or other measurable responses. The authors show that generically, all of these are confounded with each other. Distinguishing them from one another requires strong assumptions on the parametrization of the social process or on the adequacy of the covariates used (or both). In particular the authors demonstrate, with simple examples, that asymmetries in regression coefficients cannot identify causal effects and that very simple models of imitation (a form of social contagion) can produce substantial correlations between an individual's enduring traits and his or her choices, even when there is no intrinsic affinity between them. The authors also suggest some possible constructive responses to these results.     

Feasible Mechanisms in Economies with Type-Dependent Endowments

We propose two classes of allocation games for N.T.U. and T.U. exchange economies in which initial endowments and preferences depend on the agents’ private information. In both models, agents make non-verifiable claims about their types and effective deposits of consumption goods, which are redistributed by the planner. In a W-allocation game, the agents can withhold part of their endowment, namely consume whatever they do not deposit. In a D-allocation game, the agents can just destroypart of their endowment. W- and D- incentive compatible (I.C.) direct allocation mechanisms ask every agent to reveal his type and to make a deposit consistent with his reported type. The revelation principle holds in full generality for D-I.C. mechanisms but some care is needed for W-I.C. mechanisms. We further investigate the properties of both classes of mechanisms under common assumptions like non-exclusive information and/or constant aggregate endowment. In T.U. economies, W-I.C. and D-I.C. mechanisms are ex ante equivalent.     

Communicating Global Activism

Many observers doubt the capacity of digital media to change the political game. The rise of a transnational activism that is aimed beyond states and directly at corporations, trade and development regimes offers a fruitful area for understanding how communication practices can help create a new politics. The Internet is implicated in the new global activism far beyond merely reducing the costs of communication, or transcending the geographical and temporal barriers associated with other communication media. Various uses of the Internet and digital media facilitate the loosely structured networks, the weak identity ties, and the patterns of issue and demonstration organizing that define a new global protest politics. Analysis of various cases shows how digital network configurations can facilitate: permanent campaigns; the growth of broad networks despite relatively weak social identity and ideology ties; transformation of individual member organizations and whole networks; and the capacity to communicate messages from desktops to television screens. The same qualities that make these communication-based politics durable also make them vulnerable to problems of control, decision-making and collective identity.     

Strategy-proof division with single-peaked preferences and individual endowments

We consider the problem of (re)allocating the total endowment of an infinitely divisible commodity among agents with single-peaked preferences and individual endowments. We propose an extension of the so-called uniform rule and show that it is the unique rule satisfying Pareto optimality, strategy-proofness, reversibility, and an equal-treatment condition. The resulting rule turns out to be peaks-only and individually rational: the allocation assigned by the rule depends only on the peaks of the preferences, and no agent is worse off than at his individual endowment. Received: 8 September 1995/Accepted: 30 October 1996