Abstract
This paper provides a thorough second-best welfare analysis of the standard two-stage model of R&D/product market competition with R&D spillovers. The planner's solution is compared to the standard non-cooperative scenario, the R&D cartel, and the cartelized research joint venture (or joint lab). We introduce the notion of a social joint lab, as a way for the planner to avoid wasteful R&D duplication. With no spillovers, the non-cooperative scenario, the joint lab, and the second-best planner's solutions coincide. However, with spillovers, all three scenarios yield R&D investments that fall short of the socially optimal level. To shed light on the role of the spillover level on these comparisons, we observe that the gaps between the market outcomes and the planners solutions widen as the spillover parameter increases. Finally, we establish that a social planner and a social joint lab solutions may be achieved starting from any of the three scenarios by offering firms respective suitably weighted quadratic R&D subsidization schedules.

Abstract
We study price personalization in a two period duopoly with vertically differentiated products. In the second period, a firm not only knows the purchase history of all customers, as in standard Behavior Based Price Discrimination models, but it also collects detailed information on its old customers, using it to engage in price personalization. The analysis reveals that there exists a natural market for each firm, defined as the set of customers that cannot be poached by the rival in the second period. The equilibrium is unique, except when firms are ex-ante almost identical. In equilibrium, only the firm with the largest natural market poaches customers from the rival. This firm has highest profits but not necessarily the largest market share. Aggregate profits are lower than under uniform pricing. All consumers gain, total welfare is higher herein than under uniform pricing if firms' natural markets are sufficiently asymmetric. The low quality firm chooses the minimal quality level and a quality differential arises, though the exact choice for the high quality depends upon the cost specification.

Abstract
A durable good monopolist faces a continuum of heterogeneous customers who make purchase decisions by comparing present and expected price-quality offers. The monopolist designs a sequence of price-quality menus to segment the market. We consider the Markov perfect equilibrium (MPE) of a game where the monopolist is unable to commit to future price-quality menus. We obtain the novel results that: (a) under certain conditions, the monopolist covers the whole market in the first period (even when a static Mussa-Rosen monopolist would not cover the whole market), because this is a strategic means to convince customers that lower prices would not be offered in future periods and that (b) this can happen only under the stage-wise Stackelberg leadership assumption (whereby consumers base their expectations on the value of the state variable at the end of the period). Conditions under which MPE necessarily involves sequentially trading are also derived.

Abstract
In this paper, we analyze environmental regulation based on tradable emission permits in the presence of strategic interaction in an output market with differentiated products. We characterize firms' equilibrium behavior in the permits and in the output market and we show that both firms adopt "rival's cost-rising strategies". Then, we study the problem of the regulator that aims at maximizing social welfare, proposing an efficient criterion to allocate permits between firms. We find that the optimal allocation criterion requires a perfect balance between the difference on firms' price-cost margins in the permits market and the difference on firms' mark ups in the output market. In light of the previous result, we use a simulation to obtain the optimal allocation of permits between firms as a function of output market characteristics, in particular as a function of goods substitutability. © 2012 World Scientific Publishing Company.

Abstract
Network effects occur when the benefit that agents derive from a good or service depends on how many other agents adopt the same good or service. This strategic complementarity between consumers' actions has several implications on tie behavior of firms: For instance, firms need to gain advantage from early marketing stages. Network effects are intrinsically a dynamic phenomenon: past consumption of the good influences the utility of present consumers. This effect can be either direct, when consumers value interaction with their peers, and/or indirect, through an increase in the quality of the good. This chapter surveys the literature on dynamic network effects. First we provide general formulations for the modelization of network effects in a dynamic setting. Second, we analyse recent developments in the literature on firms' strategies in the context of dynamic network effects. We survey the literature both on monopoly and oligopoly markets. In the case of oligopoly markets, we distinguish between situations in which firms produce horizontally and vertically differentiated goods. Main results on pricing and evolution of market shares are exposed.

Abstract
This article analyzes price competition in it duopolistic newspaper industry. where politically differentiated newspapers compete in 2 distinct markets: circulation and advertising. Assuming that 1 of the newspapers represents the "voice of the majority," the theory of the circulation spiral is investigated and whether the interdependence between newspapers' demands in the circulation and advertising markets favors the majority's newspaper to the detriment of the minority's newspaper is investigated.