Combinatorial Voting

We study elections that simultaneously decide multiple issues, where voters have independent private values over bundles of issues. The innovation is in considering nonseparable preferences, where issues may be complements or substitutes. Voters face a political exposure problem: the optimal vote for a particular issue will depend on the resolution of the other issues. Moreover, the probabilities that the other issues will pass should be conditioned on being pivotal. We prove that equilibrium exists when distributions over values have full support or when issues are complements. We then study large elections with two issues. There exists a nonempty open set of distributions where the probability of either issue passing fails to converge to either 1 or 0 for all limit equilibria. Thus, the outcomes of large elections are not generically predictable with independent private values, despite the fact that there is no aggregate uncertainty regarding fundamentals. While the Condorcet winner is not necessarily the outcome of a multi-issue election, we provide sufficient conditions that guarantee the implementation of the Condorcet winner. © 2012 The Econometric Society

Bulk Fermions in Soft Wall Models

We discuss the implementation of bulk fermions in soft wall models. The introduction of a position dependent bulk mass allows for a well defined Kaluza-Klein expansion for bulk fermions. The realization of flavor and the contribution to electroweak precision observables are shown to be very similar to the hard wall case. The bounds from electroweak precision test are however milder with gauge boson Kaluza-Klein modes as light as $\sim 1.5$ TeV compatible with current experimental bounds.Comment: Based on seminars given by the authors. To appear in the SUSY 09 proceeding

Rivalry, Exclusion and Coalitions

Coalition formation, exclusion contest, tragedy of the commons

Characterizing behavioral decisions with choice data

This paper provides an axiomatic characterization of choices in a setting where a decision-maker may not fully internalize all the consequences of her choices on herself. Such a departure from rationality, it turns out, is common across a variety of positive behavioral models and admits the standard rational choice model as a special case. We show that choice data satisfying (a) Senís axioms if and fully characterize behavioral decisions, and (b) Senís axiom if and if fully characterize standard decision-making. In addition, we show that (a) it is possible to identify a minimal and a maximal set of psychological states using choice data alone, and (b) under specific choice scenarios, "revealed mistakes" can be inferred directly from choice data

Decisions with endogenous frames

We develop a model of decision-making with endogenous frames and contrast the normative implications of our model to those of choice theoretic models in which observed choices are determined by exogenous frames or ancillary conditions. We argue that, frames, though they may be taken as given by the decision-maker at the point when choices are made, matter for both welfare and policy purposes

Behavioural decisions & policy

We study the public policy implications of a model in which agents do not fully internalize all the conscequences of their actions. Such a model uni…es seemingly disconected models with behavioral agents. We evaluate the scope of paternalistic and libertarian-parternalistic policies in the light of our model, and propose an alternative type of approach, called soft-libertarian, which guides the decision makers in the internalization of all the conscequences of their actions. Psychotherapy is one example of a soft-libertarian policy. Moreover, we show that in our behavioral framework, policies that increase the set of opportunities or provide more information to the agent may not longer be individual welfare improving

Global Dynamics of Cosmological Expansion with Minimally Coupled Scalar Field

We give a complete description of the asymptotic behavior of a Friedmann-Robertson-Walker Universe with ``normal'' matter and a minimally coupled scalar field. We classify the conditions under which the Universe is or is not accelerating. In particular, we show that only two types of large time behavior exist: an exponential regime, and a subexponential expansion with the logarithmic derivative of the scale factor tending to zero. In the case of the subexponetial expansion the Universe accelerates when the scalar field energy density is dominant and the potential behaves in a specified manner, or if matter violates the strong energy conditon $\rho + 3p >0$. When the expansion is exponential the Universe accelerates, and the scalar field energy density is dominant. We also find that the existence of the Big Bang and a never ending expansion of the Universe constrain the equation of state of matter at large and small densities, respectively.Comment: Submitte to Phys. Lett. A. Minor changes were made to clarify some point