Differentiated Networks: Equilibrium and Efficiency

We consider a model of price competition in a duopoly with product differentiation and network effects. The value of a good for a consumer is the sum of a common and an idiosyncratic component. The first captures the vertical dimension of quality, the second captures horizontal differentiation. Each consumer privately observes his own value for each good, but cannot separate the common and the idiosyncratic component. Therefore, he has incomplete information about the value of the goods for the other consumers. After firms announce prices, consumers choose simultaneously which network to join, facing a coordination problem. In the efficient allocation, both networks are active and the firm with the highest expected quality has the largest market share. To characterize the equilibrium allocation, we derive necessary and sufficient conditions for uniqueness of the equilibrium of the coordination game played by consumers for given prices. The equilibrium allocation differs from the efficient one for two reasons. First, the equilibrium allocation of consumers to the networks is too balanced, since consumers fail to internalize network externalities. Second, if access to the networks is priced by strategic firms, then the product with the highest expected quality is also the most expensive. This further reduces the asymmetry between market shares and therefore social welfare.

Network Markets and Consumer Coordination

This paper assumes that groups of consumers in network markets can coordinate their choices when it is in their best interest to do so, and when coordination does not require communication. It is shown that multiple asymmetric networks can coexist in equilibrium if consumers have heterogeneous reservation values. A monopolist provider might choose to operate multiple networks to price differentiate consumers on both sides of the market. Competing network providers might operate networks such that one of them targets high reservation value consumers on one side of the market, while the other targets high reservation value consumers on the other side. Firms can obtain positive profits in price competition. In these asymmetric equilibria product differentiation is endogenized by the network choices of consumers. Heterogeneity of consumers is necessary for the existence of this type of equilibrium.

Network Markets and Consumer Coordination

This paper analyzes pricing decisions and competition in network markets, assuming that groups of consumers can coordinate their choices when it is in their interest, if coordination does not require communication. It is shown that multiple asymmetric networks can coexist in equilibrium. A monopolist might operate multiple ex ante identical networks to price differentiate. In Bertrand competition different firms might target high reservation value consumers on different sides of the market. Firms can obtain positive profits in price competition. Product differentiation in equilibrium is endogenized by consumers' network choices. Enough heterogeneity in reservation values is necessary for existence of these asymmetric equilibria.two-sided markets, network externalities, platform competition, coordination

Clustering in N-Player Preemption Games

sz=53 Note: The Discussion Papers in this series are prepared by members of the Department of Economics, University of Essex, for private circulation to interested readers. They often represent preliminary reports on work in progress and should therefore be neither quoted nor referred to in published work without the written consent of the author. Clustering in N-Player Preemption Games

Advanced Conducting Project

Contents include: The Stars and Stripes Forever, John Philip Sousa (1854 – 1932) Everything Beautiful, Samuel R. Hazo (b.1966) Alfred Reed (1921 – 2005

Il sogno di fuga. Traduzione dell'opera "L'Entracte" di Hélène Lenoir

Una donna, durante l'intervallo di un'opera teatrale, abborda nel foyer del teatro un uomo sconosciuto. Lui le propone di uscire a fare una passeggiata piuttosto che assistere alla seconda parte dello spettacolo...In situazioni anologhe si trovano tutti i protagonisti delle altre quattro novelle che compongono "L'Entracte" di H. Lenoir. Tutti i personaggi hanno in comune relazioni personali divenute pesanti e difficili, da cui cercano un momento di evasione, un entracte. Qui si inserisce il tema di fuga dal quotidiano che caratterizza il romanzo della Lenoir

OPTIMAL ATTITUDE MANEUVERS FOR THE KEPLER K2 MISSION

The Kepler satellite was designed to detect stars with planets capable of supporting life. After completing its primary mission, two of the satellite’s four reaction wheels failed, severely degrading the spacecraft attitude control system. In order to continue providing useful data to the scientific community, NASA has arranged a new mission for the Kepler satellite known as the K2 mission. The K2 mission currently uses a hybrid control approach for rotating the satellite that relies on thrusters for augmenting the authority of the remaining wheels. This thesis explores the application of optimal control for minimizing fuel consumption in support of the K2 mission. Such an approach is useful not only for momentum management during pointing but also for large angle slews needed to support non-science operation. Reducing fuel consumption will further extend the life of the K2 mission. Optimal control was shown in this thesis to reduce fuel consumption by as much as 28 percent during momentum management and 30 percent for large angle maneuvers. The results of this thesis are also applicable to other missions where it is desired to operate an underactuated spacecraft in the most fuel-efficient manner possible.Lieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Real-Time Supervised Detection of Pink Areas in Dermoscopic Images of Melanoma: Importance of Color Shades, Texture and Location

Background/Purpose: Early detection of malignant melanoma is an important public health challenge. In the USA, dermatologists are seeing more melanomas at an early stage, before classic melanoma features have become apparent. Pink color is a feature of these early melanomas. If rapid and accurate automatic detection of pink color in these melanomas could be accomplished, there could be significant public health benefits. Methods: Detection of three shades of pink (light pink, dark pink, and orange pink) was accomplished using color analysis techniques in five color planes (red, green, blue, hue, and saturation). Color shade analysis was performed using a logistic regression model trained with an image set of 60 dermoscopic images of melanoma that contained pink areas. Detected pink shade areas were further analyzed with regard to the location within the lesion, average color parameters over the detected areas, and histogram texture features. Results: Logistic regression analysis of a separate set of 128 melanomas and 128 benign images resulted in up to 87.9% accuracy in discriminating melanoma from benign lesions measured using area under the receiver operating characteristic curve. The accuracy in this model decreased when parameters for individual shades, texture, or shade location within the lesion were omitted. Conclusion: Texture, color, and lesion location analysis applied to multiple shades of pink can assist in melanoma detection. When any of these three details: color location, shade analysis, or texture analysis were omitted from the model, accuracy in separating melanoma from benign lesions was lowered. Separation of colors into shades and further details that enhance the characterization of these color shades are needed for optimal discrimination of melanoma from benign lesions

Perception-Theoretic Foundations of Weighted Utilitarianism

We provide a microfoundation for a weighted utilitarian social welfare function that reflects common moral intuitions about interpersonal comparisons of utilities. If utility is only ordinal in the usual microeconomic sense, interpersonal comparisons are meaningless. Nonetheless, economics often adopt utilitarian welfare functions, assuming that comparable utility functions can be calibrated, using information beyond consumer choice data. We show that consumer choice data alone are sufficient. As suggested by Edgeworth (1881), just noticeable differences (JNDs) provide a common unit of measure for interpersonal comparisons of utility differences. We prove that a simple monotonicity axiom implies a weighted utilitarian aggregation of preferences, with weights proportional to individual JNDs