Classical Predicative Logic-Enriched Type Theories

A logic-enriched type theory (LTT) is a type theory extended with a primitive mechanism for forming and proving propositions. We construct two LTTs, named LTTO and LTTO*, which we claim correspond closely to the classical predicative systems of second order arithmetic ACAO and ACA. We justify this claim by translating each second-order system into the corresponding LTT, and proving that these translations are conservative. This is part of an ongoing research project to investigate how LTTs may be used to formalise different approaches to the foundations of mathematics. The two LTTs we construct are subsystems of the logic-enriched type theory LTTW, which is intended to formalise the classical predicative foundation presented by Herman Weyl in his monograph Das Kontinuum. The system ACAO has also been claimed to correspond to Weyl's foundation. By casting ACAO and ACA as LTTs, we are able to compare them with LTTW. It is a consequence of the work in this paper that LTTW is strictly stronger than ACAO. The conservativity proof makes use of a novel technique for proving one LTT conservative over another, involving defining an interpretation of the stronger system out of the expressions of the weaker. This technique should be applicable in a wide variety of different cases outside the present work.Comment: 49 pages. Accepted for publication in special edition of Annals of Pure and Applied Logic on Computation in Classical Logic. v2: Minor mistakes correcte

ALEPH: Status Report to the PPESP

A report to the Particle Physics Experiments Selection Panel on the work of the UK members of the ALEPH Collaboration in 1997 and 1998

Demand for Slant: How Abstention Shapes Voters? Choice of News Media

Political commentators warn that the fragmentation of the modern media landscape induces voters to withdraw into ?information cocoons? and segregate along ideological lines. We show that the option to abstain breaks ideological segregation and generates ?cross-over? in news consumption: voters with considerable leanings toward a candidate demand information that is less biased toward that candidate than voters who are more centrist. This non-monotonicity in the demand for slant makes voters? ideologies non-recoverable from their choice of news media and generates disproportionate demand for media outlets that are centrist or only moderately biased. It also implies that polarization of the electorate may lead to ideological moderation in news consumption. Thus, our results cast doubt on the oft-prophesied, imminent demise of mainstream media and may help to explain recent empirical findings showing less ideological segregation in news consumption than predicted by extant theories

Maternidades anómalas : reproducción en la ciencia ficción cinematográfica de los años noventa

Aquest article s'ocupa d'un tema clau al cinema de ciència ficció dels anys noranta: la maternitat anòmala. Traça els seus antecedents històrics per a continuació distingir les seves principals tipologies: forçosa, monstruosa i alterada. Finalment, analitza cadascuna d'aquestes tipologies prenent com a exemple una pel·lícula representativa. El text pretén demostrar com aquests films actualitzen arguments tradicionals de la ciència ficció adaptant-los a les noves audiències.Este artículo se ocupa de un tema clave en el cine de ciencia ficción de los años noventa: la maternidad anómala. Traza sus antecedentes históricos para a continuación distinguir sus principales tipologías: forzosa, monstruosa y alterada. Por último, analiza cada una de ellas tomando como ejemplo una película representativa. El texto pretende demostrar cómo estos filmes actualizan argumentos tradicionales de la ciencia ficción adaptándolos a las nuevas audiencias.This paper focus on a key issue in science fiction film of the nineties: abnormal maternity. The article traces the historical background and then distinguish the main maternity typologies: forced, monstrous and altered. Finally, analyzes each of them taking a film as a representative example. The text aims to show how these films update traditional plots of science fiction adapted to the new audiences

Multi-Dimensional Causal Discovery

We propose a method for learning causal relations within high-dimensional tensor data as they are typically recorded in non-experimental databases. The method allows the simultaneous inclusion of numerous dimensions within the data analysis such as samples, time and domain variables construed as tensors. In such tensor data we exploit and integrate non-Gaussian models and tensor analytic algorithms in a novel way. We prove that we can determine simple causal relations independently of how complex the dimensionality of the data is. We rely on a statistical decomposition that flattens higher-dimensional data tensors into matrices. This decomposition preserves the causal information and is therefore suitable for structure learning of causal graphical models, where a causal relation can be generalised beyond dimension, for example, over all time points. Related methods either focus on a set of samples for instantaneous effects or look at one sample for effects at certain time points. We evaluate the resulting algorithm and discuss its performance both with synthetic and real-world data.

A Theory of Rent Seeking with Informational Foundations

I develop a model of rent seeking with informational foundations and an arbitrary number of rent seekers, and I compare the results with Tullock’s (1980) classic model where the influence activities are “blackboxed.” Given the microfoundations, the welfare consequences of rent seeking can be studied. In particular, I show that competition among rent seekers can be socially beneficial, since the additional information that the decision maker gets access to makes the increase in rent-seeking expenditures worthwhile. However, the analysis also highlights a logic that, under natural parameter assumptions, makes the rent seekers spend more resources on rent seeking than is in society’s interest, which is consistent with the spirit of the rent-seeking literature