In a multi-agent environment, where self-motivated agents try to pursue their own goals, cooperation cannot be taken for granted. Cooperation must be planned for and achieved through communication and negotiation. We present a logical model of the mental states of the agents based on a representation of their beliefs, desires, intentions, and goals. We present argumentation as an iterative process emerging from exchanges among agents to persuade each other and bring about a change in intentions. We look at argumentation as a mechanism for achieving cooperation and agreements. Using categories identified from human multi-agent negotiation, we demonstrate how the logic can be used to specify argument formulation and evaluation. We also illustrate how the developed logic can be used to describe different types of agents. Furthermore, we present a general Automated Negotiation Agent which we implemented, based on the logical model. Using this system, a user can analyze and explore differe...

Abstract not found

Abstract not found

Why do charities often begin new capital fund drives by announcing a large contribution by a single wealthy donor? This paper explores the possibility that such “leadership giving ” provides a signal to all other givers that the charity is of high quality. The dilemma is that if the lead giver can deceive others to believe the charity is of higher quality than it truly is, then these followers will make larger contributions, which will benefit the leader. Hence, the leader must give an unusually large amount to convey a credible signal of the quality. This sets up a warof-attrition game for who will pay the cost to signal the quality. Since the wealthy have the lowest opportunity cost of providing the signal, they, in equilibrium, move first to provide the signal of quality with exceptionally large gifts. 1.

The extent to which the observed procedures for selling new issues are efficient is studied. We show that a posted-price mechanism, in conjunction with nonbinding preplay communication and participation restrictions, leads to an allocation of the security (and payment) that maximizes the seller's expected revenue, given the informational constraints imposed by the optimizing incentives of the potential buyers. Consider a firm that is going public for the first time. While potential investors may have some information about the cash flows of the enterprise, for issues not previously traded there often is considerable residual uncertainty concerning the market’s valuation of these cash flows. Consequently, we expect strategic considerations to be important in the market for unseasoned issues. Two questions arise: what is ah optimal mechanism for selling such securities and how do procedures followed in practice relate to optimal mechanisms? We gratefully acknowledge the comments of the editor (Michael Brennan), the referee (Milt Harris), and participants at presentation of this article at

Austen-Smith and Banks (Journal of Economic Theory, 2000) study how money burning can expand the set of pure cheap talk equilibria of Crawford and Sobel (Econometrica, 1982). I identify an error in the main Theorem of Austen-Smith and Banks, and provide a variant that preserves some of the important implications. I also prove that cheap talk can be influential with money burning if and only if it can be influential without money burning. This strengthens a result of Austen-Smith and Banks, but uncovers other errors in their analysis. Finally, an open conjecture of theirs is proved correct.

Restricting attention to the class of extensive games defined by von Neumann and Morgenstern with the added assumption of perfect recall, we specify the information of each player at each node of the game-tree in a way which is coherent with the original

An appropriate (interim) notion of the core for an economy with incomplete information depends on the amount of information that coalitions can share. The coarse and fine core, as originally defined by Wilson (1978), correspond to two polar cases, involving no information sharing and arbitrary information sharing, respectively. We propose a new core notion, the credible core, which incorporates incentive compatibility constraints, and is based on the idea that a coalition can coordinate its potential objection to a status-quo over an event that can be credibly inferred from the nature of the objection being contemplated. We provide sufficient conditions ensuring non-emptiness of the credible core.

Firms in the computer industry are often accused of vaporware, the untruthful pre-announcement of a new version of their product. By claiming they have a new product, critics argue, these firms try to deter potential entrants. The paper analyzes this phenomenon. It shows that vaporware is an equilibrium strategy in a signaling game in which the possibility to market a new product is private information. In this model, the possibility of vaporware can hurt consumers, also in the case the incumbent does have a new version of its product. The welfare effects of vaporware are ambiguous. I.

This paper examines breakup fees and stock lockups as devices for prospective target firms to encourage bidder participation in takeover contest. We show that, unless bidding costs for the first bidder are too high, breakup fees provide for the socially desirable degree of competition and ensure the efficient allocation of the target to the highest valued buyer in a takeover auction. In contrast, stock lockups permit the target firm to subsidize entry of a new bidder at the expense of an incumbent bidder. Stock lockups induce too much competition when offered to a second bidder and too little competition when offered to a first bidder. Despite their socially wasteful properties, target management would favor stock lockups as they induce takeover competition at least cost to the target.