Unifying time-to-build theory

Several contributions have recently reconsidered the role of the time to build assumption in explaining some relevant stylized facts. In this paper, the similarities and differences which may emerge when the time to build structure of capital is introduced in a continuous or discrete time framework are studied and enlightened. The most striking difference lies in the dimensionality of the two frameworks, which is always finite in discrete but infinite in continuous time. Then, the deterministic version of the traditional time to build model developed by Kydland and Prescott is presented, and it is shown how the typical time to build model setup in continuous time can be obtained. Moreover, the richest dynamics in continuous time is investigated and, more importantly, it is shown that the predictions in terms of capital, output, and consumption behavior are not signi¯cantly di®erent from its discrete version once the economy is calibrated properly.Discrete and continuous time, time-to-build, mixed functional differential equa- tions.

Unifying Time-to-Build Theory

Several contributions have recently reconsidered the role of the time to build assumption in explaining some relevant stylized facts. In this paper, the similarities and differences which may emerge when the time to build structure of capital is introduced in a continuous or discrete time framework are studied and enlightened. The most striking difference lies in the dimensionality of the two frameworks, which is always finite in discrete but infinite in continuous time. Then, the deterministic version of the traditional time to build model developed by Kydland and Prescott is presented, and it is shown how the typical time to build model setup in continuous time can be obtained. Moreover, the richest dynamics in continuous time is investigated and, more importantly, it is shown that the predictions in terms of capital, output, and consumption behavior are not signi¯cantly di®erent from its discrete version once the economy is calibrated properly

Dualities among 1T-Field Theories with Spin, Emerging from a Unifying 2T-Field Theory

The relation between two time physics (2T-physics) and the ordinary one time formulation of physics (1T-physics) is similar to the relation between a 3-dimensional object moving in a room and its multiple shadows moving on walls when projected from different perspectives. The multiple shadows as seen by observers stuck on the wall are analogous to the effects of the 2T-universe as experienced in ordinary 1T spacetime. In this paper we develop some of the quantitative aspects of this 2T to 1T relationship in the context of field theory. We discuss 2T field theory in d+2 dimensions and its shadows in the form of 1T field theories when the theory contains Klein-Gordon, Dirac and Yang-Mills fields, such as the Standard Model of particles and forces. We show that the shadow 1T field theories must have hidden relations among themselves. These relations take the form of dualities and hidden spacetime symmetries. A subset of the shadows are 1T field theories in different gravitational backgrounds (different space-times) such as the flat Minkowski spacetime, the Robertson-Walker expanding universe, AdS(d-k) x S(k) and others, including singular ones. We explicitly construct the duality transformations among this conformally flat subset, and build the generators of their hidden SO(d,2) symmetry. The existence of such hidden relations among 1T field theories, which can be tested by both theory and experiment in 1T-physics, is part of the evidence for the underlying d+2 dimensional spacetime and the unifying 2T-physics structure.Comment: 33 pages, LaTe

Manifestations of projection-induced memory: General theory and the tilted single file.

Over the years the field of non-Markovian stochastic processes and anomalous diffusion evolved from a specialized topic to mainstream theory, which transgressed the realms of physics to chemistry, biology and ecology. Numerous phenomenological approaches emerged, which can more or less successfully reproduce or account for experimental observations in condensed matter, biological and/or single-particle systems. However, as far as their predictions are concerned these approaches are not unique, often build on conceptually orthogonal ideas, and are typically employed on an ad hoc basis. It therefore seems timely and desirable to establish a systematic, mathematically unifying and clean approach starting from more fine-grained principles. Here we analyze projection-induced ergodic non-Markovian dynamics, both reversible as well as irreversible, using spectral theory. We investigate dynamical correlations between histories of projected and latent observables that give rise to memory in projected dynamics, and rigorously establish conditions under which projected dynamics is Markovian or renewal. A systematic metric is proposed for quantifying the degree of non-Markovianity. As a simple, illustrative but non-trivial example we study single file diffusion in a tilted box, which, for the first time, we solve exactly using the coordinate Bethe ansatz. Our results provide a solid foundation for a deeper and more systematic analysis of projection-induced non-Markovian dynamics and anomalous diffusion

(WP 2018-05) Specialization, Fragmentation, and Pluralism in Economics

This paper investigates whether specialization in research is causing economics to become an increasingly fragmented and diverse discipline with a continually rising number of niche-based research programs and a declining role for dominant cross-science research programs. It opens by framing the issue in terms of centrifugal and centripetal forces operating on research in economics, and then distinguishes descriptive from normative pluralism. It reviews recent research regarding the JEL code and the economics’ J. B. Clark Award that points towards rising specialization and fragmentation of research in economics. It then reviews five related arguments that might explain increasing specialization and fragmentation in economics: (i) Smith’s early division of labor view, (ii) Kuhn’s later thinking about the importance of specialization, (iii) Heiner’s behavioral burden of knowledge argument, (iv) Ross innovation-diffusion analysis and Arthur’s theory of technological change as determinants of specialization in science, and (v) the effects of space and culture or internationalization on innovation appropriation. The paper then discusses what descriptive pluralism implies about normative pluralism, and makes a case for multidisciplinarity over interdisciplinarity as a basis for arguments promoting pluralism. The paper closes with brief comments on the issue of specialization and pluralism in the wider world outside economics and science

Automated Reasoning over Deontic Action Logics with Finite Vocabularies

In this paper we investigate further the tableaux system for a deontic action logic we presented in previous work. This tableaux system uses atoms (of a given boolean algebra of action terms) as labels of formulae, this allows us to embrace parallel execution of actions and action complement, two action operators that may present difficulties in their treatment. One of the restrictions of this logic is that it uses vocabularies with a finite number of actions. In this article we prove that this restriction does not affect the coherence of the deduction system; in other words, we prove that the system is complete with respect to language extension. We also study the computational complexity of this extended deductive framework and we prove that the complexity of this system is in PSPACE, which is an improvement with respect to related systems.Comment: In Proceedings LAFM 2013, arXiv:1401.056

Representational unification in cognitive science: Is embodied cognition a unifying perspective?

In this paper, we defend a novel, multidimensional account of representational unification, which we distinguish from integration. The dimensions of unity are simplicity, generality and scope, non-monstrosity, and systematization. In our account, unification is a graded property. The account is used to investigate the issue of how research traditions contribute to representational unification, focusing on embodied cognition in cognitive science. Embodied cognition contributes to unification even if it fails to offer a grand unification of cognitive science. The study of this failure shows that unification, contrary to what defenders of mechanistic explanation claim, is an important mechanistic virtue of research traditions