This book is about the construction of reality. The central aim of this study is to understand how gravity works and how it may be focused and manipulated. While I do not have an answer to this question, the discoveries along the way have been worth collecting into a single volume for future reference.

En la tercera parte de El ser y la nada, Jean-Paul Sartre profundiza en un elemento fundamental de la tensión ser-nada: el prójimo. La libertad como necesidad imperiosa e irrenunciable de ser se orienta-enel-mundo, pero también reconoce la importancia de las relaciones con el otro como reflejo de la objetivación que se desprende de la conciencia de algo. En este horizonte, resulta interesante pensar esas relaciones como actos comunicativos que reconocen el conflicto y la inmediata necesidad de una comunicación solidaria en medio de dicho conflicto.

Social networks amplify inequalities due to fundamental mechanisms of social tie formation such as homophily and triadic closure. These forces sharpen social segregation reflected in network fragmentation. Yet, little is known about what structural factors facilitate fragmentation. In this paper we use big data from a widely-used online social network to demonstrate that there is a significant relationship between social network fragmentation and income inequality in cities and towns. We find that the organization of the physical urban space has a stronger relationship with fragmentation than unequal access to education, political segregation, or the presence of ethnic and religious minorities.

We investigate multi-agent epistemic modal logic with common knowledge modalities for groups of agents and obtain van Benthem style model-theoretic characterisations, in terms of bisimulation invariance of classical first-order logic over the non-elementary classes of (finite or arbitrary) common knowledge Kripke frames. The technical challenges posed by the reachability and transitive closure features of the derived accessibility relations are dealt with through passage to (finite) bisimilar coverings of epistemic frames by Cayley graphs of permutation groups whose generators are associated with the agents.

Many factors such as economy size, capital resources, and size of national publication market seem to be related to the scientific performance of nations. In this paper we link the national culture values with scientific performance of 53 nations. We focus on the year 2010. Our study uses three datasets: 1) Hofstede’s data on national culture, 2) data on migration share of societies, and 3) citation impact data. We found that four dimensions of culture (i.e. individualism, power distance, uncertainty avoidance, and indulgence) correlate practically and statistically significantly with scientific impact of nations. The findings are discussed in mirror of cultural theories.

“This paper introduces a new task and a new dataset”, “we improve the state of the art in X by Y” — it is rare to find a current natural language processing paper (or AI paper more generally) that does not contain such statements. What is mostly left implicit, however, is the assumption that this necessarily constitutes progress, and what it constitutes progress towards.

Desde el descubrimiento de los campos Liza y luego Payara, han aflorado muchas promesas sobre el inminente crecimiento de la producción de hidrocarburos de Guyana. De acuerdo con información reportada por autoridades guyanesas, el plan comprende para la fase I un tope de producción @ F/A’2020 de 120.000 B/D, con un costo de equilibrio de $35 por barril. Para la fase II se visualiza una producción máxima de 180.000 B/D @ 200.000 B/D, con un costo de equilibrio de $25 por barril. Aunque Guyana aun tiene pendiente armar el marco regulatorio de la ley de extracción de hidrocarburos, régimen fiscal aplicable, participación del estado y esquema de leyes de protección ambiental, la información inicial apunta sin embargo hacia un esquema 50/50 gobierno/operador..

We address a recent proposal concerning ‘surplus structure’ due to Nguyen et al. [‘Why Surplus Structure is Not Superfluous.’ Br. J. Phi. Sci. Forthcoming.] We argue that the sense of ‘surplus structure’ captured by their formal criterion is importantly different from—and in a sense, opposite to—another sense of ‘surplus structure’ used by philosophers. We argue that minimizing structure in one sense is generally incompatible with minimizing structure in the other sense. We then show how these distinctions bear on Nguyen et al.’s arguments about Yang-Mills theory and on the hole argument.

We present a full formalization in Martin-Löf’s Constructive Type Theory of the Standardization Theorem for the Lambda Calculus using first-order syntax with one sort of names for both free and bound variables and Stoughton’s multiple substitution. Our formalization is based on a proof by Ryo Kashima, in which a notion of beta-reducibility with a standard sequence is captured by an inductive relation. The proof uses only structural induction over the syntax and the relations defined, which is possible due to the specific formulation of substitution that we employ. The whole development has been machine-checked using the system Agda.

The traditional view of evidence in mathematics is that evidence is just proof and proof is just derivation. There are good reasons for thinking that this view should be rejected: it misrepresents both historical and current mathematical practice. Nonetheless, evidence, proof, and derivation are closely intertwined. This paper seeks to tease these concepts apart. It emphasizes the role of argumentation as a context shared by evidence, proofs, and derivations. The utility of argumentation theory, in general, and argumentation schemes, in particular, as a methodology for the study of mathematical practice is thereby demonstrated. Argumentation schemes represent an almost untapped resource for mathematics education. Notably, they provide a consistent treatment of rigorous and non-rigorous argumentation, thereby working to exhibit the continuity of reasoning in mathematics with reasoning in other areas.