Explicit Local Integrals of Motion for the Many-Body Localized State

Recently, it has been suggested that the Many-Body Localized phase can be characterized by local integrals of motion. Here we introduce a Hilbert space preserving renormalization scheme that iteratively finds such integrals of motion exactly. Our method is based on the consecutive action of a similarity transformation using displacement operators. We show, as a proof of principle, localization and the delocalization transition in interacting fermion chains with random onsite potentials. Our scheme of consecutive displacement transformations can be used to study Many Body Localization in any dimension, as well as disorder-free Hamiltonians.Comment: 5 pages, 2 figures, and Supplementary Information. Second version contains new numerical result

- A MODEL OF VOTING WITH INCOMPLETE INFORMATION AND OPINION POLLS

A one-dimensional model of spatial political competition with incomplete information is developed.It is assumed that voters care about the distribu-tion of votes among the two candidates. Votershave an incomplete infor-mation about the distribution of voters´ types. We provide conditions forwhich the publication of opinion polls may solve the informational problem voters face. The mainresult states that only when the distribution of voters is polarized we could expect that voters actas if they were fully informed.Spatial competition, Incomplete Information, Opinion Polls.

Robust implementation under alternative information structures

In this paper we consider a model in which agents have complete information about their neighbours and, possibly, incomplete information about the rest of the economy. We consider two different informational frameworks. In the first, agents do not have priors about what is going on in the rest of the economy. In the second, agents are supposed to have priors about the unknown characteristics. We present a mechanism which any social choice correspondence satisfying monotonicity and no veto powet in both informational settings for every possible prior thus requiring little knowledge from the point of view of the designer of the information possesed by agents about the economy

Tax enforcement problems

We study an income tax enforcement problem using a principal-agent model where the government sets the tax and inspection functions. These are announced to the agents and there is no commitment problem. The penalty function for dishonest taxpayers is given exogenously and satisfies certain social norms. We prove that, for a large family of penalty functions, this policy is such that honesty implies regressiveness. This result does not depend on the fact that agents know the true probability of inspection.Publicad

- IDEOLOGICAL VERSUS DOWNSIAN POLITICAL COMPETITION

We analyze a one-dimensional model of spatial political competition with two parties and uncertainty on the distribution of voters types. We assume that parties are formed by regular members and professional politicians; members care about the policy enacted, while professional politicians, on the contrary, only care about winning the election. We consider two possibilities: that members choose the political platforms and that professional politicians are the ones who choose such platforms. The expected utility for party members is analyzed under these two cases. We find that when professional politicians have no informational advantage, it is on the interest of both parties to let professional politicians choose the platforms. Only in the case in which professional politicians have much better information than the members of the party about voters is it possible that party members obtain a greater expected utility choosing the platforms themselves rather than letting the professional politicians choose.party competition, delegation, asymmetric information

Income taxation, uncertainty and stability

This paper develops a political model to analyze the stability of income tax schedules. It is assumed that agents perceive any proposed alternative tax policy as more uncertain than the status quo. A tax policy is stable if it is a Condorcet winner. It is well known that in a model without uncertainty the existence of such a policy is very rare. We show, however, that in real cases this might not be a serious problem since small amounts of uncertainty can bring stability to the status quo. It is also shown that linear tax functions can only be stable in economies with very egalitarian income distributions and high taxation levelsPublicad

Income taxation, uncertainty and stability.

This paper develops a political model to analyze the stability of income tax schedules. It is assumed that agents perceive any proposed alternative tax policy as more uncertain than the status quo. A tax policy is stable if it is a Condorcet winner. It is well known that in a model without uncertainty the existence of such a policy is very rare. We show, however, that in real cases this might not be a serious problem since small amounts of uncertainty can bring stability to the status quo. It is also shown that linear tax functions can only be stable in economies with very egalitarian income distributions and high taxation levelsMajority voting; Income taxation; Uncertainty; Status quo;

Tax enforcement problems.

We study an income tax enforcement problem using a principal-agent model where the government sets the tax and inspection functions. These are announced to the agents and there is no commitment problem. The penalty function for dishonest taxpayers is given exogenously and satisfies certain social norms. We prove that, for a large family of penalty functions, this policy is such that honesty implies regressiveness. This result does not depend on the fact that agents know the true probability of inspection.