Coupled Dynamics in the Phillips Machine Model of the Macroeconomy

In this paper it is claimed that the Phillips machine is a nonlinear mechanism. Phillips (1950) presented his machine as being described with a linear differential equation. In this paper it is claimed that the machine is better described with a system of nonlinear difference.-differential equations. This system itself is approximated by a set of nonlinear differential equations. This differential equations are of the Hicks-Goodwin flexible multiplier accelerator type. Consistently with this conjecture and following Phillips’ suggestion we have presented a ‘digital’ simulation of two coupled would-be Phillips machines.computable economics; flexible-accelerator, coupled dynamical systems, Goodwin, Phillips machine, MONIAC

Online Ensemble Learning of Sensorimotor Contingencies

Forward models play a key role in cognitive agents by providing predictions of the sensory consequences of motor commands, also known as sensorimotor contingencies (SMCs). In continuously evolving environments, the ability to anticipate is fundamental in distinguishing cognitive from reactive agents, and it is particularly relevant for autonomous robots, that must be able to adapt their models in an online manner. Online learning skills, high accuracy of the forward models and multiple-step-ahead predictions are needed to enhance the robots’ anticipation capabilities. We propose an online heterogeneous ensemble learning method for building accurate forward models of SMCs relating motor commands to effects in robots’ sensorimotor system, in particular considering proprioception and vision. Our method achieves up to 98% higher accuracy both in short and long term predictions, compared to single predictors and other online and offline homogeneous ensembles. This method is validated on two different humanoid robots, namely the iCub and the Baxter

Functional RG flow equation: regularization and coarse-graining in phase space

Starting from the basic path integral in phase space we reconsider the functional approach to the RG flow of the one particle irreducible effective average action. On employing a balanced coarse-graining procedure for the canonical variables we obtain a functional integral with a non trivial measure which leads to a modified flow equation. We first address quantum mechanics for boson and fermion degrees of freedom and we then extend the construction to quantum field theories. For this modified flow equation we discuss the reconstruction of the bare action and the implications on the computation of the vacuum energy density.Comment: 19 pages, latex, few remarks and an equation added, version to be published on Phys. Rev.

Technological Progress in Italian Regions: Some Comparisons

In this paper we study technological progress in a set of representative Italian regions. The analysis is conducted using input-output data. We construct the technological frontiers and calculate new indices of technological progress (see Fredholm and Zambelli 2009 and Zambelli and Fredholm 2010). The empirical results are robust and seem to be interesting. We find, for the years 2001 and 2004 that Trentino and Sicily are the regions, among those examined, with the largest number of technologically advanced productive methods, while Veneto and Lombardy are characterized by poor relative technological performance. Given the micro data about observed productivity this result is, at first, surprising, but we provide an interpretation. In the case of the Trentino region the technological progress is actually exploited so that the region is near to full employment and the income generated is relatively high. In the case of Sicily our results show that there is a great potential for growth which is not exploited. Veneto and Lombardy seem to be cases in which the embodied technological progress is not high, this indicates, ceteris paribus, a low potential for future growth or, alternatively, that the development has occurred in the past. Good performance is also indicated by Emilia Romagna.Technological Progress, Technological Frontier, Productivity, Regional Economy

Functional RG flow of the effective Hamiltonian action

After a brief review of the definition and properties of the quantum effective Hamiltonian action we describe its renormalization flow by a functional RG equation. This equation can be used for a non-perturbative quantization and study also of theories with bare Hamiltonians which are not quadratic in the momenta. As an example the vacuum energy and gap of quantum mechanical models are computed. Extensions of this framework to quantum field theories are discussed. In particular one possible Lorentz covariant approach for simple scalar field theories is developed. Fermionic degrees of freedom, being naturally described by a first order formulation, can be easily accommodated in this approach.Comment: 31 pages, late

The Epistemology of Simulation, Computation and Dynamics in Economics Ennobling Synergies, Enfeebling 'Perfection'

Lehtinen and Kuorikoski ([73]) question, provocatively, whether, in the context of Computing the Perfect Model, economists avoid - even positively abhor - reliance on simulation. We disagree with the mildly qualified affirmative answer given by them, whilst agreeing with some of the issues they raise. However there are many economic theoretic, mathematical (primarily recursion theoretic and constructive) - and even some philosophical and epistemological - infelicities in their descriptions, definitions and analysis. These are pointed out, and corrected; for, if not, the issues they raise may be submerged and subverted by emphasis just on the unfortunate, but essential, errors and misrepresentationsSimulation, Computation, Computable, Analysis, Dynamics, Proof, Algorithm

Computation in Economics

This is an attempt at a succinct survey, from methodological and epistemological perspectives, of the burgeoning, apparently unstructured, field of what is often – misleadingly – referred to as computational economics. We identify and characterise four frontier research fields, encompassing both micro and macro aspects of economic theory, where machine computation play crucial roles in formal modelling exercises: algorithmic behavioural economics, computable general equilibrium theory, agent based computational economics and computable economics. In some senses these four research frontiers raise, without resolving, many interesting methodological and epistemological issues in economic theorising in (alternative) mathematical modesClassical Behavioural Economics, Computable General Equilibrium theory, Agent Based Economics, Computable Economics, Computability, Constructivity, Numerical Analysis

HIP10680/HIP10679: a visual binary in the β\beta Pictoris Association with the fastest rotating member

We present the results of a multi-filter photometric monitoring of the wide binary HIP10680/HIP10679. We found both component to be variable with amplitude up to $\Delta$V = 0.03 mag in the case of HIP10680 and $\Delta$V = 0.07 mag in the case of HIP10679. We could measure the rotation periods P = 0.2396d of the hotter F5V component HIP10680 and P = 0.777d of the cooler G5V component HIP10679. We found that the rotation axes of both components are aligned with an inclination $i$ = $\sim$ 10$^{\circ}$. Although the two components have a mass difference not larger than 15%, they exhibit a significant difference between their rotation periods. Such difference may arise either from different initial rotation periods or to different disc life times. For instance, the slower rotating component HIP 10679 hosts a well know debris disc.Comment: In press by IBVS in Information Bulletin on Variable Stars, 201