Two necessary conditions for strategy-proofness: on what domains are they also sufficient?

A social choice function may or may not satisfy a desirable property depending on its domain of definition. For the same reason, different conditions may be equivalent for functions defined on some domains, while different in other cases. Understanding the role of domains is therefore a crucial issue in mechanism design. We illustrate this point by analyzing the role of different conditions that are always related, but not always equivalent to strategy-proofness. We define two very natural conditions that are necessary for strategy-proofness: monotonicity and reshuffling invariance. We remark that they are not always sufficient. Then, we identify a domain condition, called intertwinedness, that ensures the equivalence between our two conditions and that of strategy-proofness. We prove that some important domains are intertwined: those of single-peaked preferences, both with public and private goods, and also those arising in simple models of house allocation. We prove that other necessary conditions for strategy-proofness also become equivalent to ours when applied to functions defined on intertwined domains, even if they are not equivalent in general. We also study the relationship between our domain restrictions and others that appear in the literature, proving that we are indeed introducing a novel proposal.

Clustering or scattering: the underlying reason for regulating distance among retail outlets

Concerns on the clustering of retail industries and professional services in main streets had traditionally been the public interest rationale for supporting distance regulations. Although many geographic restrictions have been suppressed, deregulation has hinged mostly upon the theory results on the natural tendency of outlets to differentiate spatially. Empirical evidence has so far offered mixed results. Using the case of deregulation of pharmacy establishment in a region of Spain, we empirically show how pharmacy locations scatter, and that there is not rationale for distance regulation apart from the underlying private interest of very few incumbents.

Individualització de la programació docent de Fonaments de Computadors

La metodologia docent impulsada per la creació d’un Espai Europeu d’Ensenyament Superior comú implica tenir en compte el treball de l’estudiant. En aquest sentit, resulta molt convenient facilitar a l’alumnat de primers cursos l’adaptació a una docència que s’organitza en crèdits ECTS i que se centra en el procés d’aprenentatge dels estudiants. Per aquest motiu, l’objectiu d’aquest projecte ha estat que assumissin un grau més elevat de responsabilitat en l’aprenentatge i que adquirissin una competència més gran en l’organització del temps d’acord amb els programes docents de les assignatures que cursessin. Per aconseguir-ho, s’ha creat un entorn de presentació de les guies docents basat en les agendes d’activitats d’aprenentatge. Aquestes agendes són, de fet, planificacions de les activitats presencials i no presencials que han de dur a terme els estudiants per assolir els objectius de cadascuna de les assignatures que fan. Perquè siguin efectives, han de ser el més individuals possibles i amb la informació suficient com perquè les activitats es puguin dur a terme. Així, els alumnes disposen d’una veritable agenda particular del què han de fer i quan per seguir una assignatura determinada. Com a resultat del projecte s’ha proposat una organització de la informació d’una assignatura que facilita tant la gestió de les guies docents com la creació d’agendes d’activitats d’aprenentatge, s’ha establert una metodologia de presentació dels programes docents amb suport de web perquè sigui de fàcil consulta i en els que els vincles de cada activitat s’activen segons el ritme del curs i, finalment, s’ha aplicat tot per al cas de l’assignatura de Fonaments de computadors, aconseguint que l’alumnat s’acostumi a seguir les agendes d’activitats i, consegüentment, a millorar el rendiment acadèmic de l’assignatura, que era el que, es pretenia originalment.

Testing for sufficient information in structural VARs

We derive necessary and sufficient conditions under which a set of variables is informationally sufficient, i.e. it contains enough information to estimate the structural shocks with a VAR model. Based on such conditions, we suggest a procedure to test for informational sufficiency. Moreover, we show how to amend the VAR if informational sufficiency is rejected. We apply our procedure to a VAR including TFP, unemployment and per-capita hours worked. We find that the three variables are not informationally sufficient. When adding missing information, the effects of technology shocks change dramatically.

Abortion in public reason

What abortion laws a liberal political community ought to have? Much has been said about the moral problem of abortion, but there has not been yet (to my knowledge) a fully articulate account of the bearing of the competing answers to this ethical problem on liberal public reason. The first part of my project consists in a critical review of the different attempts to solve the various philosophical puzzles, both metaphysical and moral, posed by the abortion problem. Why is it wrong to kill beings like you and me? By answering this question we shall gain a better insight into those properties we have that give us such strong reasons against killing beings like us. Here we face a tremendous philosophical diffuculty, for it is not possible to determine what the robustest account of the wrongness of killing is without dealing with deeper metaethical and metaphysical problems. Indeed, consequentialist and nonconsequentialist moral theories differ in what it is that makes an action morally wrong -is it just the outcome of the action as compared with the outcomes of its alternatives? Or is it something else? Also, what are we essentially? Is the foetus merely our precursor? Then killing a foetus is relevantly similar to contraception. Or is the foetus one of us? If so, when we kill it, are we depriving it of a future as valuable as ours? Perhaps the relation of identity (the fact that it is its future as opposed to someone else's) doesn't matter. That may be because the foetus is an aggregate of biological and psychological facts and perhaps aggregates are not substances. Or maybe it is a substance but only psychological realtions matter, not personal identity. The second part of my project has to do with the different status these metaphisical and ethical positions ought to have in liberal public reason. Though this is the part in which most research is still needed, my own intuition is that, given the depth of the philosphical views in competition, restrictive abortion laws ought to be considered unrespectful to citizens' autonomy.

Necessary and sufficient conditions for robust stability using modal intervals

In this paper, robustness of parametric systems is analyzed using a new approach to interval mathematics called Modal Interval Analysis. Modal Intervals are an interval extension that, instead of classic intervals, recovers some of the properties required by a numerical system. Modal Interval Analysis not only simplifies the computation of interval functions but allows semantic interpretation of their results. Necessary, sufficient and, in some cases, necessary and sufficient conditions for robust performance are presented

Emotion and reason in everyday risk perception

Although research has documented the importance of emotion in risk perception, little is knownabout its prevalence in everyday life. Using the Experience Sampling Method, 94 part-timestudents were prompted at random via cellular telephones to report on mood state and threeemotions and to assess risk on thirty occasions during their working hours. The emotions valence, arousal, and dominance were measured using self-assessment manikins (Bradley &Lang, 1994). Hierarchical linear models (HLM) revealed that mood state and emotions explainedsignificant variance in risk perception. In addition, valence and arousal accounted for varianceover and above reason (measured by severity and possibility of risks). Six risks were reassessedin a post-experimental session and found to be lower than their real-time counterparts.The study demonstrates the feasibility and value of collecting representative samples of data withsimple technology. Evidence for the statistical consistency of the HLM estimates is provided inan Appendix.