An improved Belief Propagation algorithm finds many Bethe states in the random field Ising model on random graphs

We first present an empirical study of the Belief Propagation (BP) algorithm, when run on the random field Ising model defined on random regular graphs in the zero temperature limit. We introduce the notion of maximal solutions for the BP equations and we use them to fix a fraction of spins in their ground state configuration. At the phase transition point the fraction of unconstrained spins percolates and their number diverges with the system size. This in turn makes the associated optimization problem highly non trivial in the critical region. Using the bounds on the BP messages provided by the maximal solutions we design a new and very easy to implement BP scheme which is able to output a large number of stable fixed points. On one side this new algorithm is able to provide the minimum energy configuration with high probability in a competitive time. On the other side we found that the number of fixed points of the BP algorithm grows with the system size in the critical region. This unexpected feature poses new relevant questions on the physics of this class of models.Comment: 20 pages, 8 figure

The Effect of Entry on R&D Investment of Leaders: Theory and Empirical Evidence

We develop a simple model of competition for the market that shows that, contrary to the Arrow view, endogenous entry threat in a market induces the average firm to invest less in R&D and the incumbent leader to invest more. We test these predictions with a Tobit model based on a unique dataset and survey for the German manufacturing sector (the Mannheim Innovation Panel). We confirm the empirical validity of our predictions and perform a number of robustness test with instrumental variables. --R&D,Entry,Endogenous market structures,Leadership

Convergence Rates of Approximation by Translates

In this paper we consider the problem of approximating a function belonging to some funtion space Φ by a linear comination of n translates of a given function G. Ussing a lemma by Jones (1990) and Barron (1991) we show that it is possible to define function spaces and functions G for which the rate of convergence to zero of the erro is 0(1/n) in any number of dimensions. The apparent avoidance of the "curse of dimensionality" is due to the fact that these function spaces are more and more constrained as the dimension increases. Examples include spaces of the Sobolev tpe, in which the number of weak derivatives is required to be larger than the number of dimensions. We give results both for approximation in the L2 norm and in the Lc norm. The interesting feature of these results is that, thanks to the constructive nature of Jones" and Barron"s lemma, an iterative procedure is defined that can achieve this rate

Value Stocks and Growth Stocks: A Study of the Italian Market

This article focuses on the study of value and growth stocks in the Italian market during the period 2001-2018, trying to understand if there is a difference in terms of return between the two share classes and which could be the explanation. The analysis reveals a persistent and large value premium in the early 2000s, while after the financial crisis the premium diminished considerably. The excess return provided by value stocks was marked and persistent only in case of smaller firms, while in case of large-cap stocks the phenomenon was limited and present only in the early years of the 21st century. Finally, the analysis suggests that value stocks are not particularly riskier than growth stocks. Therefore, it seems that, at least in part, the value premium in the Italian market may present a mispricing explanation

TRIPBAM: Leveraging Digital Data Streams to Unleash Savings

TRIPBAM pioneered automated clustered rate monitoring in the hotel industry. After capturing a traveler’s reservation, TRIPBAM software scrutinized the digital data stream of changing room rates and notified users of any potential savings. While TRIPBAM could successfully discover savings for its many customers, its executives focused on the challenge of turning TRIPBAM into a resilient, viable business going forward. Many questions awaited a clear answer. Was the consumer space the one that had the greatest potential or should the firm focus exclusively on the corporate market? How could TRIPBAM protect its early advantage from its inevitable imitators? Both the consumer and business opportunities looked wide open even though each side presented distinct challenges to growth. To achieve profitability, TRIPBAM needed to not just grow the user base but also seek a unique position in the market to defend against the increasing number of startups entering their space. The case provides substantial data and information for students to step in the shoes of TRIPBAM’s executives and provide some answers to the above questions

Inverse diffraction for the Atmospheric Imaging Assembly in the Solar Dynamics Observatory

The Atmospheric Imaging Assembly in the Solar Dynamics Observatory provides full Sun images every 1 seconds in each of 7 Extreme Ultraviolet passbands. However, for a significant amount of these images, saturation affects their most intense core, preventing scientists from a full exploitation of their physical meaning. In this paper we describe a mathematical and automatic procedure for the recovery of information in the primary saturation region based on a correlation/inversion analysis of the diffraction pattern associated to the telescope observations. Further, we suggest an interpolation-based method for determining the image background that allows the recovery of information also in the region of secondary saturation (blooming)

Researching European Crime Narratives and the Role of Television: An Introduction

none3siWhat is the role of television in the building and development of local and transnational identities, through the production, distribution and circulation of European crime dramas? Some main trajectories.openBarra, Luca; Jaquelin, Alice; Pagello, FedericoBarra, Luca; Jaquelin, Alice; Pagello, Federic

Out of our skull, in our skin: the Microbiota-Gut-Brain axis and the Extended Cognition Thesis

AbstractAccording to a shared functionalist view in philosophy of mind, a cognitive system, and cognitive function thereof, is based on the components of the organism it is realized by which, indeed, play a causal role in regulating our cognitive processes. This led philosophers to suggest also that, thus, cognition could be seen as an extended process, whose vehicle can extend not only outside the brain but also beyond bodily boundaries, on different kinds of devices. This is what we call the 'Externally Extended Cognition Thesis.' This notion has generated a lively debate. Here, we offer a novel notion of extended cognition, according to which cognition can be seen as being realized (and expanded) outside the brain, but still inside the body. This is what we call the 'Internally Extended Cognition Thesis'. Not only our thesis but also our approach while defending it is innovative. The argument we offer is supported by recent empirical findings in the life sciences and biomedicine, which suggest that the gut microbiota's activity has a functional role in regulating our cognitive processes and behaviors. In doing so, we embrace theholobiont-perspective, according to which it is possible to claim that what we call biological individuals are not autonomous entities with clear boundaries, but should rather be seen as networks of multiple interactions among species. Thus, by analyzing different sets of evidence in light of theholobiont-perspective, we argue that the gut microbiota could be seen as a component of our organism. On the basis of the philosophical interpretation of this evidence, however, we also suggest that there are no impediments standing the way of considering the gut microbiota also as a functional extension of our cognitive system. If so, this amounts to extending cognition out of 'our skull', though still confining it within 'our body': to 'our gut'. This is an instance of the 'Internally Extended Cognition Thesis,' whose benefits for an original (biologically informed) theory ofextended cognitionare discussed

Innovation strategies and firm growth

In this work, we explore the relations between sales growth and a set of innovation indicators that capture the different sources, modes and results of the innovative activity undertaken within firms. We exploit a rich panel on innovation activity of Spanish manufacturing firms, reporting detailed CIS-type information continuously over the period 2004-2011. Standard GMMpanel estimates of the average effect of innovation activities reveal significant and positive effect for internal R&D, while no effect is found for external sourcing of knowledge (external R&D, acquisition of embodied and disembodied technologies) as well as for output of innovation (process and product innovation). However, fixed-effects quantile regressions reveal that innovation activities, apart from process innovation and disembodied technical change, display a positive effect on high-growth performance. Finally, we find evidence of super-modularity of the growth function, revealing complementarities of internal R&D with product innovation, and between product and process innovation