A multi-agent-based model for a negotiation support system in electronic commerce

This study proposes a multi-agent-based model for bilateral multi-objective negotiation in electronic commerce trading. The function and behaviour of several types of agents are discussed. These agents interact with each other in our negotiation support system model to create the most appropriate solution for both negotiating parties. In particular, we are concerned with a win-win negotiation approach in which agents seek to strike a fair deal that also maximizes the payoff for everyone involved. That is, if the opponent cannot accept an offer then the proponent should endeavour to find an alternative to make a trade-off. Against this background, a utility model based on fuzzy constraint satisfaction problems is proposed to ensure that these agents reach a solution that is fair for both negotiating parties if such a solution exists. The model uses prioritized fuzzy constraints to indicate how concessions should be made when necessary. In addition, by incorporating the notion of a negotiation argument into our evaluation model, the agents can sometimes reach agreements that would otherwise be impossible. Finally, a numerical example is given to display the applicability of the proposed approach for electronic trading assistance.     

Unemployment insurance in a sticky-price model with worker moral hazard

This paper studies the role of unemployment insurance in a sticky-price model that features an efficiency-wage view of the labor market based on unobservable effort. The risk-sharing mechanism central to the model permits, but does not force, agents to be fully insured. Structural parameters are estimated using a maximum-likelihood procedure on US data. Formal hypothesis tests reveal that the data favor a model in which agents only partially insure each other against employment risk. The results also show that limited risk sharing helps the model capture many salient properties of the business cycle that a restricted version with full insurance fails to explain.     

Tests for bounded rationality with a linear dynamic model distorted by heterogeneous expectations

The purpose of this paper is to develop a methodology which will use economic data to detect the existence of boundedly rational economic agents. The bounded rationality model presented in this paper generalizes a linear dynamic rational expectations model by nesting two types of expectations. In this paper, it is claimed that the bounded rationality model as presented can be transformed into an optimal regulator problem with distortions. As a result, the methodologies developed by the optimal control theory can be used to solve the model. The likelihood function for the model is constructed by the Kalman filtering using the solution of the model. Maximum Likelihood Estimation (MLE) is performed to test for bounded rationality in the U.S. cattle market for the period from 1900 to 1990. The empirical results indicate that some fraction of economic agents in the market are boundedly rational.     

Taxing capital is a good idea: The role of idiosyncratic risk in an OLG model

We investigate an overlapping generations (OLG) model in which agents who live for two periods receive idiosyncratic productivity shocks when they are old. We show that, around zero tax equilibria, we can always construct a combination of a small capital tax and a lump-sum transfer that are Pareto-improving. As Dávila et al. (Econometrica (2012)) show, a capital reduction in one period raises the welfare level of agents who are old in that period, but lowers that of the young agents, because it reduces their wages. We show that the government can compensate for these wage losses by additionally taxing the old agents, such that their welfare gains remain positive. Our result is unchanged when earnings are uncertain at young age.     

Global recessions as a cascade phenomenon with interacting agents

This paper examines global recessions as a cascade phenomenon. In other words, how recessions arising within one or more countries might percolate across a network of connected economies. An agent based model is set up in which the agents are Western economies. A country has a probability of entering recession in any given year and one of emerging from it the next. In addition, the agents have a threshold propensity, which varies across time, to import a recession from the agents most closely connected to them. The agents are connected on a network, and an agent’s neighbours at any time are either in (state 1) or out (state 0) of recession. If the weighted sum exceeds the threshold, the agent also goes into recession. Annual real GDP growth for 17 Western countries 1871–2006 is used as the data set. The model is able to replicate three key features of the statistical distribution of recessions: the distribution of the number of countries in recession in any given year, the duration of recessions within the individual countries, and the distribution of ‘wait time’ between recessions i.e. the number of years between them. The network structure is important for the interacting agents to replicate the stylised facts. The country-specific probabilities of entering and emerging from recession by themselves give results which are by no means as well matched to the actual data. We are grateful to an anonymous referee for some extremely helpful comments.     

Non-self-averaging in macroeconomic models: a criticism of modern micro-founded macroeconomics

When the coefficient of variation, namely the ratio of the standard deviation over the mean approaches zero as the number of economic agents becomes large, a system is called self-averaging. Otherwise, it is non-self-averaging. Most economic models take it for granted that the economic system is self-averaging. However, they are based on the extremely unrealistic assumption that all the economic agents face the same probability distribution, and that micro shocks are independent. Once these unrealistic assumptions are dropped, non-self-averaging behavior naturally emerges. Using a simple stochastic growth model, this paper demonstrates that the coefficient of variation of aggregate output or GDP does not go to zero even if the number of sectors or economic agents goes to infinity. Non-self-averaging phenomena imply that even if the number of economic agents is large, dispersion could remain significant, and we cannot legitimately focus solely on the means of aggregate variables. This, in turn, means that the standard microeconomic foundations based on representative agents have little value for they are meant to provide us with accurate dynamics of the means of aggregate variables. Contrary to the main stream view, micro-founded macroeconomics such as a dynamic general equilibrium model does not provide solid micro foundations.     

Optimal policy in a model of endogenous fluctuations and assets

Assets are coupled to endogenous aggregate output fluctuations in a model of heterogeneous agents. Those agents wish to avoid reacting inadvertently to an unobservable noise process, but to do so must elicit reactions to that noise from each other. An abstract institution is modeled that optimizes this elicitation by strategically transmitting information about aggregates; I designate this feedback. Feedback is used by agents and so influences the characteristics of aggregate fluctuations. The optimal feedback policy minimizes asset rates of return, maximizes the persistence of aggregate output fluctuations, and causes the distribution of wealth to widen continually and without limit.     

Is labour market training a curse for the unemployed? Evidence from a social experiment

In 1994 a social experiment was conducted in Denmark, where unemployed applicants for classroom training were randomised into treatment and control groups. The data are contaminated by the presence of no‐shows and crossovers, biasing the traditional experimental estimator. We interpret our experiment within an economic model of agents maximising outcomes facing different cost regimes and present results interpretable within this model. Surprisingly, we find that classroom training significantly increases individual unemployment rates and decreases employability. We discuss possible reasons for this finding and some related policy issues. Copyright © 2009 John Wiley & Sons, Ltd.     

Zero-intelligence agents looking for a job

We study a simple agent-based model of a decentralized matching market game in which agents (workers or job seekers) make proposals to other agents (firms) in order to be matched to a position within the firm. The aggregate result of agents interactions can be summarised in the form of a Beveridge curve, which determines the relationship between unmatched agents, unemployed job seekers and vacancies in firms. We open the black box of matching technology, by modelling how agents behave (make proposals) according to their information perception. We observe more efficient results—in the form of a downward shift of the Beverage curve in the case of simple zero-intelligent agents. Our comparative statics indicate that market conditions, such as the heterogeneity of agents’ preferences, will also shift the Beveridge curve downwards. Moreover, market thickness affects movement along the Beverage curve. Movement right-down along the curve if there is an increasing number of agents compared to positions within firms. Furthermore, we show that frictions in re-matching, such as commitment to a match, could be another factor shifting the Beveridge curve toward the origin.     

Towards a credit network based early warning indicator for crises

This paper presents an agent based model which underlines the importance of credit network and leverage dynamics in determining the resilience of the system, defining an early warning indicator for crises. The model reproduces macroeconomic dynamics emerging from the interactions of heterogeneous banks and firms in an endogenous credit network. Banks and firms are linked through multiple credit relations, which derive from individual target leverage choices: agents choose the more convenient leverage level, according to a basic reinforcement learning algorithm. Simulations are calibrated on balance sheet data of banks and firms quoted in the Japanese stock-exchange markets from 1980 to 2012.     

Sales contests,promotion decisions and heterogeneous risk

This paper examines a general model of sales contests in which agents have heterogeneous attitudes toward risk. It shows that agents that are less risk averse have a higher probability of success. A corollary to this result shows that when absolute risk aversion is decreasing in wealth, wealthier agents have a higher probability of promotion. The same wealth effect makes it possible for more risk averse agents to take greater risks in a multi‐round promotion tournament. Next, a stability analysis shows that these equilibria are attractors under a best response dynamic. While it is well‐known that sales contests can be an effective incentive device for eliciting effort from employees, this research suggests the added benefit that when used as a basis for promotion decisions, sales contests act to filter the hardest working agents to the top of the corporate hierarchy. Copyright © 2008 John Wiley & Sons, Ltd.     

Retirement and social security: the roles of self-fulfilling expectations and educational investments

Countries with higher implicit taxes on continued work are associated with lower labor force participation rates of the elderly. This paper constructs a politico-economic model that accounts for this feature based on multiple, self-fulfilling expectations of agents. In this model, agents are identical at birth and can become skilled (or remain unskilled) through educational investment. When agents hold expectations of larger social security benefits, it provides a disincentive to engage in educational investment, thereby resulting in an unskilled majority. In turn, this unskilled majority supports larger social security benefits, which induces the retirement of the elderly and thus results in a lower labor force participation rate. The opposite applies when agents have expectations of smaller social security benefits in their old age.     

Investments in education and welfare in a two-sector,random matching economy

We consider a random matching model where heterogeneous agents choose optimally to invest time and real resources in education. Generically, there is a steady state equilibrium where some agents, but not all of them, invest. Regular steady state equilibria are constrained inefficient in a strong sense. The Hosios (1990) condition is neither necessary nor sufficient for constrained efficiency. We also provide restrictions on the fundamentals sufficient to guarantee that equilibria are characterized by overeducation (or undereducation), present some results on their comparative statics properties, and discuss the nature of welfare improving policies.     

The Blocking Lemma for a many-to-one matching model

The Blocking Lemma identifies a particular blocking pair for each non-stable and individually rational matching that is preferred by some agents of one side of the market to their optimal stable matching. Its interest lies in the fact that it has been an instrumental result to prove key results on matching. For instance, the fact that in the college admissions problem the workers-optimal stable mechanism is group strategy-proof for the workers and the strong stability theorem in the marriage model follow directly from the Blocking Lemma. However, it is known that the Blocking Lemma and its consequences do not hold in the general many-to-one matching model in which firms have substitutable preference relations. We show that the Blocking Lemma holds for the many-to-one matching model in which firms’ preference relations are, in addition to substitutable, quota q-separable. We also show that the Blocking Lemma holds on a subset of substitutable preference profiles if and only if the workers-optimal stable mechanism is group strategy-proof for the workers on this subset of profiles.     

Equivalence of the Core and Competitive Equilibrium in a Tiebout Economy with Crowding Types

We propose a new model of a local public goods economy with differentiated crowding. The new feature is that taste and crowding characteristics of agents are distinguished from one another. We prove that if the economy satisfies strict small group effectiveness then the core is equivalent to the set of Tiebout equilibrium outcomes. Equilibrium prices are defined to depend solely on crowding characteristics. This implies that only publicly observable information, and not private information such as preferences, is needed to induce agents to sort themselves into efficient jurisdictions. Thus, our model allows us to satisfy Bewley's[6]anonymity requirement on taxes in his well-known criticism of the Tiebout hypothesis.     

Anonymous price taking equilibrium in Tiebout economies with a continuum of agents: Existence and characterization

We introduce a model of a local public goods economy with a continuum of agents and jurisdictions with finite but unbounded populations, where the set of possible projects for each jurisdiction/club is unrestricted in size. Under boundedness of per capita payoffs, which simply ensures that equal treatment payoffs are bounded above, we apply results of Kaneko and Wooders (1986) to obtain nonemptiness of the core of the economy. We then demonstrate, under the stronger condition of strict small group effectiveness, that the equal treatment core coincides with the set of price-taking equilibrium outcomes with anonymous prices—that is, prices for public goods depend only on observable characteristics of agents. Existence of equilibrium follows from nonemptiness of the core and equivalence of the core to the set of equilibrium outcomes. Our approach provides a new technique for showing existence of equilibrium in economies with a continuum of agents.     

Imperfect information and the house price in a general-equilibrium model

House prices have inertia, which may be because housing-market participants need time to recognize long booms and recessions. Within a dynamic stochastic general-equilibrium model with an endogenous market for housing, I consider the case of rational expectations subject to imperfect information about the persistence of exogenous shocks. I evaluate the performance of the model against the last 40 years of key U.S. macroeconomic data. Bayesian comparison strongly favors the model over the baseline case with perfect information. Under imperfect information, agents rely on learning to form expectations, which improves the ability of the model to generate realistic low-frequency house-price dynamics. However, as long as the agents form expectations rationally, the improvement is limited. Furthermore, to confine price inertia within the housing market is a challenge for the general-equilibrium approach.     

Are hyperinflation paths learnable?

Earlier studies of the seigniorage inflation model have found that the high-inflation steady state is not stable under learning. We reconsider this issue and analyze the full set of solutions for the linearized model. Our main focus is on stationary hyperinflationary paths near the high-inflation steady state. These paths are shown to be stable under least-squares learning if agents can utilize contemporaneous data. In an economy with a mixture of agents, some of whom only have access to lagged data, stable hyperinflationary paths emerge only if the proportion of agents with access to contemporaneous data is sufficiently high.     

On a theorem of Schmeidler

Over a decade ago D. Schmeidler (1973) introduced a concept of non-cooperative equilibrium for games with a continuum of agents and, under a restriction on the payoff functions, established the existence of an equilibrium in pure strategies. The purpose of this note is to reformalize the model and the equilibrium notion of Schmeidler in terms of distributions rather than measurable functions. We shall see how once the definitions are available we get (pure strategy) equilibrium existence theorems quite effortlessly and under general conditions. A number of remarks contain applications to, among others, incomplete information games.     

Asset price and wealth dynamics in a financial market with heterogeneous agents

This paper considers a discrete-time model of a financial market with one risky asset and one risk-free asset, where the asset price and wealth dynamics are determined by the interaction of two groups of agents, fundamentalists and chartists. In each period each group allocates its wealth between the risky asset and the safe asset according to myopic expected utility maximization, but the two groups have heterogeneous beliefs about the price change over the next period: the chartists are trend extrapolators, while the fundamentalists expect that the price will return to the fundamental. We assume that investors’ optimal demand for the risky asset depends on wealth, as a result of CRRA utility. A market maker is assumed to adjust the market price at the end of each trading period, based on excess demand and on changes of the underlying reference price. The model results in a nonlinear discrete-time dynamical system, with growing price and wealth processes, but it is reduced to a stationary system in terms of asset returns and wealth shares of the two groups. It is shown that the long-run market dynamics are highly dependent on the parameters which characterize agents’ behaviour as well as on the initial condition. Moreover, for wide ranges of the parameters a (locally) stable fundamental steady state coexists with a stable ‘non-fundamental’ steady state, or with a stable closed orbit, where only chartists survive in the long run: such cases require the numerical and graphical investigation of the basins of attraction. Other dynamic scenarios include periodic orbits and more complex attractors, where in general both types of agents survive in the long run, with time-varying wealth fractions.