Ironing without control

I extend Myersonʼs [R. Myerson, Optimal auction design, Math. Oper. Res. 6 (1981) 58–73] ironing technique to more general objective functions. The approach is based on a generalized notion of virtual surplus which can be maximized pointwise even when the monotonicity constraint implied by incentive compatibility binds. It is applicable to quasilinear principal-agent models where the standard virtual surplus is weakly concave in the allocation or appropriately separable in the allocation and type. No assumptions on allocation rules are required beyond monotonicity.Yrjö Jahnsson Foundatio

Infinite-Horizon Mechanism Design

These notes examine the problem of how to extend envelope theorems to infinite-horizon dynamic mechanism design settings, with an application to the design of "bandit auctions."asymmetric information, stochastic processes, incentives, mechanism design JEL Classification Numbers: D82, C73, L1.

Dynamic Mechanism Design: Incentive Compatibility, Profit Maximization and Information Disclosure

This paper examines the problem of how to design incentive-compatible mechanisms in environments in which the agents' private information evolves stochastically over time and in which decisions have to be made in each period. The environments we consider are fairly general in that the agents' types are allowed to evolve in a non-Markov way, decisions are allowed to affect the type distributions and payoffs are not restricted to be separable over time. Our first result is the characterization of a dynamic payoff formula that describes the evolution of the agents' equilibrium payoffs in an incentive-compatible mechanism. The formula summarizes all local first-order conditions taking into account how current information affects the dynamics of expected payoffs. The formula generalizes the familiar envelope condition from static mechanism design: the key difference is that a variation in the current types now impacts payoffs in all subsequent periods both directly and through the effect on the distributions of future types. First, we identify assumptions on the primitive environment that guarantee that our dynamic payoff formula is a necessary condition for incentive compatibility. Next, we specialize this formula to quasi-linear environments and show how it permits one to establish a dynamic "revenue-equivalence" result and to construct a formula for dynamic virtual surplus which is instrumental for the design of optimal mechanisms. We then turn to the characterization of sufficient conditions for incentive compatibility. Lastly, we show how our results can be put to work in a variety of applications that include the design of profit-maximizing dynamic auctions with AR(k) values and the provision of experience goods.dynamic mechanisms, asymmetric information, stochastic processes, incentives

Patents Hinder Collusion

We argue that a patent system makes collusion among innovators more difficult. Our simple argument is based on two properties of the patent system. First, a patent not only protects against infringement but also against retaliation by former collusion members. Second, a deviator has an equal chance with former collusion members to get a patent on new innovations. We show that if a patent system reduces spillovers, it renders collusion impossible. Moreover, it is possible to design a patent system that simultaneously increases knowledge spillovers and eliminates collusionPatens, Collusion, Secrecy, Innovation

Patents and strategic firm behavior

Only abstract. Paper copies of master’s theses are listed in the Helka database (http://www.helsinki.fi/helka). Electronic copies of master’s theses are either available as open access or only on thesis terminals in the Helsinki University Library.Vain tiivistelmä. Sidottujen gradujen saatavuuden voit tarkistaa Helka-tietokannasta (http://www.helsinki.fi/helka). Digitaaliset gradut voivat olla luettavissa avoimesti verkossa tai rajoitetusti kirjaston opinnäytekioskeilla.Endast sammandrag. Inbundna avhandlingar kan sökas i Helka-databasen (http://www.helsinki.fi/helka). Elektroniska kopior av avhandlingar finns antingen öppet på nätet eller endast tillgängliga i bibliotekets avhandlingsterminaler.In this thesis we analyze how patent policy affects the strategic behavior of firms. We develop an infinite horizon model of innovation where each period firms are randomly matched to ideas which can be developed into innovations. The model allows for simultaneous independent discovery so that the number of firms producing the same innovation is determined endogenously. The issues that we consider are (1) innovators' optimal choice of protection between patents and (trade) secrecy, and (2) the effect of patents on the firms' ability to sustain tacit collusion. In studying the choice of protection, we find that firms may find it optimal to patent even if patent protection is weaker than protection under secrecy. This follows because of the prisoner's dilemma created by the patent policy: If no one else patents, the firm gets the patent and the corresponding monopoly profits for sure whereas secrecy yields only oligopoly profits in the event that there are others that have developed the same innovation. On the hand, if the competitors patent when successful, then secrecy yields positive profits only when no competitor is successful with the same innovation. Applying for the patent gives the innovator a chance of receiving a monopoly even when others are successful. This explains how the patent policy can at the same time enhance incentives to innovate and increase the spreading of information through increased spillovers. We show that welfare maximizing patent policy may either reduce or increase spillovers. Turning to the effects of patents on the competitiveness of an industry, we argue that a patent system makes collusion among innovators more difficult. Our argument is based on two properties of the patent system. First, a patent not only protects against infringement but also against punishment by former collusion members. Second, a deviator has an equal chance with the former collusion members to get a patent on future innovations. We show that if a patent system reduces spillovers, it renders collusion impossible. Moreover, it is possible to design a patent system that simultaneously increases knowledge spillovers and eliminates collusion

Mechanisms for Repeated Trade

How does feasibility of efficient repeated trade depend on the features of the environment such as persistence of values, private information about their evolution, or trading frequency? We derive a necessary and sufficient condition for efficient, unsubsidized, and voluntary trade, which implies that efficient contracting requires sufficient congruence of expectations. This translates to bounds on persistence of values and on private information about their evolution, and distinguishes increasing patience from more frequent interaction; the latter need not facilitate efficiency even when the former does. We also discuss second-best mechanisms and extend the characterization to general dynamic collective choice problems

Efficiency in Games With Markovian Private Information

We study repeated Bayesian games with communication and observable actions in which the players' privately known payoffs evolve according to an irreducible Markov chain whose transitions are independent across players. Our main result implies that, generically, any Pareto-efficient payoff vector above a stationary minmax value can be approximated arbitrarily closely in a perfect Bayesian equilibrium as the discount factor goes to 1. As an intermediate step, we construct an approximately efficient dynamic mechanism for long finite horizons without assuming transferable utility

Developing the Mechanics of Plusminus: Designing for Emergence and Control in a Physics-Based Game

“Plusminus” is a single-player action-puzzle-adventure game about magnetism, with mechanics developed to promote emergent gameplay. Agency, the ability to make choices, is an important factor in players’ enjoyment of games, and emergent gameplay can facilitate such agency. However, as emergence often arises in unexpected ways, it can also result in players feeling a lack of control and reduced agency. Furthermore, players expect physics in games to act consistently, according to the world around us, but their understanding and expectations of some physical phenomena like magentism may vary and be incomplete. This makes designing mechanics that promote emergence in a physics-based game challenging. In “Plusminus”, we augmented a physics system with magnetism, and gave players meaningful control over it, to promote emergent gameplay and agency. The thesis contributes an approximate model of magnetic forces that ensures stable simulation, game design flexibility, and still conforms well enough to player expectations. More specifically, 1) to enable the player to turn objects into monopole magnets of positive or negative polarity, we simulate Coulomb forces between charged particles and shells, instead of actual magnetic fields. 2) To ensure stable simulation and allow the player to better anticipate simulation behaviour, each magnet has a maximum “field radius” visualised as a transparent bubble, and two magnets only attract or repel each other if their field bubbles intersect. This allows players and level designers to initiate and prevent interactions in a precise manner, and also prevents objects in separate game areas from affecting each other uncontrollably. 3) To ensure that forces produce stable and controllable interactions regardless of scale, the forces are computed such that the maximum possible accelerations produced between two magnets depends only on the mass ratio between them, as opposed to a combination of masses and magnetic charges. This reduces the number of variables that need balancing, making it easier to achieve a stable simulation. The findings improved player controllability while maintaining opportunities for emergence, in a way that matches player expectations of physics

Infinite-horizon mechanism design: The independent-shock approach

These notes examine the problem of how to extend envelope theorems to infinite-horizon dynamic mechanism design settings, with an application to the design of bandit auctions