Contractible contracts in common agency problems

This article analyses contractual situations between many principals and many agents. The agents have private information, and the principals take actions. Principals have the ability to contract not only on the reports of the agents but also on the contracts offered by other principals. Contracts are required to be representable in a formal language. The main result of the article is a characterization of the allocations that can be implemented as equilibria in our contracting game. We then restrict attention to exclusive-contracting environments, in which the agent may select the contract of at most one principal. In this setting, our characterization result implies that principals can collude to implement the monopolist outcome. Finally, in general, equilibrium contracts turn out to be incomplete. That is, a contract will restrict the action space of a principal but will not necessarily determine a single action

The Price of Advice

We develop a model of consulting (advising) where the role of the consultant is that she can reveal signals to her client which refine the client’s original private estimate of the profitability of a project. Importantly, only the client can observe or evaluate these signals, the consultant cannot. We characterize the optimal contract between the consultant and her client. It is a menu consisting of pairs of transfers specifying payments between the two parties (from the client to the consultant or vice versa) in case the project is undertaken by the client and in case it is not. The main result of the paper is that in the optimal mechanism, the consultant obtains the same profit as if she could evaluate the impact of the signals (whose release she controls) on the client’s profit estimate.Mechanism Design, Information Disclosure, Consulting, Advising

Optimal monitoring design

This paper considers a Principal–Agent model with hidden action in which the Principal can monitor the Agent by acquiring independent signals conditional on effort at a constant marginal cost. The Principal aims to implement a target effort level at minimal cost. The main result of the paper is that the optimal information-acquisition strategy is a two-threshold policy and, consequently, the equilibrium contract specifies two possible wages for the Agent. This result provides a rationale for the frequently observed single-bonus wage contracts

Dynamic contracting: an irrelevance theorem

This paper generalizes a conceptual insight in dynamic contracting with quasilinear payoffs: the principal does not need to pay any information rents for extracting the agent's “new” private information obtained after signing the contract. This is shown in a general model in which the agent's type stochastically evolves over time, and her payoff (which is linear in transfers) depends on the entire history of private and any contractible information, contractible decisions, and her hidden actions. The contract is offered by the principal in the presence of initial informational asymmetry. The model can be transformed into an equivalent one where the agent's subsequent information is independent in each period (type orthogonalization). We show that for any fixed decision–action rule implemented by a mechanism, the agent's rents (as well as the principal's maximal revenue) are the same as if the principal could observe and contract on the agent's orthogonalized types after the initial period. We also show that any monotonic decision–action rule can be implemented in a Markovian environment satisfying certain regularity conditions, and we provide a simple “recipe” for solving such dynamic contracting problems

An alternative to signaling: directed search and substitution

This paper analyzes a labor market, where (i) workers can acquire an observable skill at no cost, (ii) firms differ in unobserved productivity, (iii) workers' skill and firms' productivity are substitutes and (iv) firms' search is directed. The main result is that, if the entry cost of firms is small, no worker acquires the skill in the unique equilibrium. For intermediate entry costs, a positive measure of workers obtain the skill, and the number of skilled workers goes to one as entry costs become large. Welfare is highest when the entry cost is high

Surplus sharing in Cournot oligopoly

We characterize equilibria of oligopolistic markets where identical rms with constant marginal cost compete a' la Cournot. For given maximal willingness to pay and maximal total demand, we rst identify all combinations of equilibrium consumer surplus and industry prot that can arise from arbitrary demand functions. Then, as a further restriction, we x the average willingness to pay above marginal cost (i.e., rst-best surplus) and identify all possible triples of consumer surplus, industry prot and deadweight loss

Buyer-optimal learning and monopoly pricing

This paper analyzes a bilateral trade model where the buyer’s valuation for the object is uncertain and she observes only a signal about her valuation. The seller gives a take-it-or-leave-it offer to the buyer. Our goal is to characterize those signal structures which maximize the buyer’s expected payoff. We identify a buyer-optimal signal structure which generates (i) efficient trade and (ii) a unitelastic demand. Furthermore, we show that every other buyer-optimal signal structure yields the same outcome as the one we identify: in particular, the same pric

Kemokinek, kemokin receptorok expressziójának regulációja tumor sejteken = Regulation of chemokine and chemokine receptor expression in tumor cells

A tumor és mikrokörnyezete közötti kapcsolatban a kemokineknek és a tumor sejteken található kemokin receptoroknak mind nagyobb jelentőséget tulajdonítanak. Vizsgáltuk egy primer humán colorectális adenocarcinomából, ugyanezen beteg máj- és peritoneális metasztázisaiból létrehozott tumor sejtvonalak (Isreco-1, -2, -3), egy normál colon epitheliális sejtvonal, továbbá a cervicális carcinoma eredetű HeLa sejtek konstitutív citokin, illetve kemokin termelését, és a CXC kemokin sztromális sejt faktor-1a (SDF-1a) erre gyakorolt hatását. Míg az Isreco-1 sejtek IL-8-at, RANTES-t és IL-10-et, az Isreco-2 és Isreco-3 sejtek ennél nagyobb mennyiségű IL-8-t, RANTES-t, továbbá TGF-b1-t és IL-6-t (Isreco-3) termeltek. SDF-1a fokozta az IL-8 termelést az Isreco-1 és kis mértékben a normál colon epitheliális sejtekben. HeLa sejtekben az IL-6 termelést is serkentette. A colorectális eredetű és a HeLa sejteken kimutattuk az SDF-1a?receptorát (CXCR4), és a CCR7 gén expresszióját. HeLa sejtekben CCR10 mRNS-t is találtunk. Gátlószerek segítségével kimutattuk, hogy az SDF-1a-nak az IL-8 és IL-6 termelés serkentésében játszott szerepe nem Galfai proteinhez kötött folyamat HeLa és Isreco-1 sejtekben. Mindkét esetben a JAK3, az IL-8 esetében a JAK2 és a JNK/SAPK útvonal szerepe is felmerül. Eredményeink arra utalnak, hogy az SDF-1a fontos szerepet játszhat a CXCR4+ tumor sejtek citokin termelésének modulációjában, túlmutatva ezzel a tumor sejtek migrációjára gyakorolt ismert hatásán. | Chemokines and tumor cell chemokine receptors have been increasingly shown to be involved in the interaction between tumor cells and their local microenvironment. In order to characterize differences between tumor cells obtained from primary and metastatic human colorectal carcinoma constitutive and stromal cell-derived factor-1a (SDF-1a)-modulated cytokine/chemokine secretions were determined in culture supernatants of cell lines derived from the primary tumor (Isreco-1), liver (Isreco-2) and peritoneal metastases (Isreco-3) of the same patient. Effect of SDF-1a on tumor cell cytokine production was also studied in human cervical carcinoma HeLa cells. Our results showed that Isreco-2 and Isreco-3 cells secreted significantly higher levels of IL-8, TGF-b1, RANTES than Isreco-1 cells. In addition, Isreco-1 cells secreted IL-10, Isreco-3 cells produced IL-6. SDF-1a induced an increase in IL-8 production in Isreco-1, IL-8 and IL-6 production in HeLa cells. The SDF-1a receptor CXCR4 was found on all tumor and normal colon cells. Besides, CCR7 mRNA was detected in all cells, CCR10 mRNA in HeLa. SDF-1a enhanced IL-8 and IL-6 production in a Galphai-independent manner. Our findings indicate the involvement of JAK3 in tumor cell IL-8 and IL-6 response, and an additional role for JAK2 and JNK in IL-8 response to SDF-1a. Our findings support a regulatory role for SDF-1? in tumor cell cytokine production