The Saving Glut Explanation of Global Imbalances: the Role of Underinvestment

According to the “Saving Glut hypothesis”, global imbalances are caused by inefficiently high level of precautionary savings in financially underdeveloped regions, where agents have limited opportunity to diversify idiosyncratic risk. This paper generalizes the approach by modeling idiosyncratic risk in entrepreneurial activities, which can be only partially hedged. As a result, agents save too much and invest too little, relative to the efficient allocation, depressing production activities and the real interest rate. Capital account liberalization towards financially more advanced economies then produces an outflow of capital in search of safer investment, with the effect of further reducing domestic investment in countries with poor financial institutions. The model predicts welfare losses for less financially developed economies, and an increase in wealth inequality for advanced economies. Finally, the present analysis is able to explain the direct link between the financial crisis and global recession and the long run implications of worsening financial conditions on countries’ net external positions.Current Account, Financial Markets, Heterogeneity, Incomplete Markets, International Capital Movements

Implementing feedback in creative systems : a workshop approach

One particular challenge in AI is the computational modelling and simulation of creativity. Feedback and learning from experience are key aspects of the creative process. Here we investigate how we could implement feedback in creative systems using a social model. From the field of creative writing we borrow the concept of a Writers Workshop as a model for learning through feedback. The Writers Workshop encourages examination, discussion and debates of a piece of creative work using a prescribed format of activities. We propose a computational model of the Writers Workshop as a roadmap for incorporation of feedback in artificial creativity systems. We argue that the Writers Workshop setting describes the anatomy of the creative process. We support our claim with a case study that describes how to implement the Writers Workshop model in a computational creativity system. We present this work using patterns other people can follow to implement similar designs in their own systems. We conclude by discussing the broader relevance of this model to other aspects of AI

Reserve management and sovereign debt cost in a world with liquidity crises

The accumulation of large amount of sovereign reserves has fuelled an intense debate on the associated costs. In a world with liquidity crises and strategic default, we model a contracting game between international lenders and a country, which delivers the country's optimal portfolio choice and the cost of sovereign debt: at equilibrium, the sovereign allocates the borrowed resources to either liquid reserves or an illiquid and risky production project. We study how the opportunity cost of hoarding reserves is affected by the financial and technological characteristics of the economy. In line with recent empirical evidence, we find two important results: the cost of debt decreases in the level of reserves if the probability of liquidity shocks is high enough; however the cost of debt increases in reserves when the lenders anticipate that the country has an incentive to default after a liquidity shock. Indeed, we show that the country may choose to retain reserves instead of employing them to inject the liquidity needed to bring the production project to maturity.sovereign debt, international reserves, liquidity shock, strategic default

Exact ICL maximization in a non-stationary time extension of the latent block model for dynamic networks

The latent block model (LBM) is a flexible probabilistic tool to describe interactions between node sets in bipartite networks, but it does not account for interactions of time varying intensity between nodes in unknown classes. In this paper we propose a non stationary temporal extension of the LBM that clusters simultaneously the two node sets of a bipartite network and constructs classes of time intervals on which interactions are stationary. The number of clusters as well as the membership to classes are obtained by maximizing the exact complete-data integrated likelihood relying on a greedy search approach. Experiments on simulated and real data are carried out in order to assess the proposed methodology.Comment: European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning (ESANN), Apr 2015, Bruges, Belgium. pp.225-230, 2015, Proceedings of the 23-th European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning (ESANN 2015

X575: writing rengas with web services

Our software system simulates the classical collaborative Japanese poetry form, renga, made of linked haikus. We used NLP methods wrapped up as web services. Our experiments were only a partial success, since results fail to satisfy classical constraints. To gather ideas for future work, we examine related research in semiotics, linguistics, and computing.Comment: 4 pages; submitted to CC-NLG - Computational Creativity in Natural Language Generatio

Double bubbles in the 3-torus

We present a conjecture, based on computational results, on the area minimizing way to enclose and separate two arbitrary volumes in the flat cubic 3-torus. For comparable small volumes, we prove that an area minimizing double bubble in the 3-torus is the standard double bubble from R^3.Comment: 13 pages, 4 figures. Prepared on behalf of the participants in the Clay Mathematics Institute Summer School on the Global Theory of Minimal Surfaces, held at the Mathematical Sciences Research Institute in Berkeley, California, Summer 200

Exact ICL maximization in a non-stationary temporal extension of the stochastic block model for dynamic networks

The stochastic block model (SBM) is a flexible probabilistic tool that can be used to model interactions between clusters of nodes in a network. However, it does not account for interactions of time varying intensity between clusters. The extension of the SBM developed in this paper addresses this shortcoming through a temporal partition: assuming interactions between nodes are recorded on fixed-length time intervals, the inference procedure associated with the model we propose allows to cluster simultaneously the nodes of the network and the time intervals. The number of clusters of nodes and of time intervals, as well as the memberships to clusters, are obtained by maximizing an exact integrated complete-data likelihood, relying on a greedy search approach. Experiments on simulated and real data are carried out in order to assess the proposed methodology

Arundo donax L. per la produzione di biogas

La tematica dell’energia rinnovabile assume un’importanza di rilievo crescente nella società odierna. A tal riguardo, la digestione anerobica è ad oggi uno dei sistemi più diffuso per la valorizzazione energetica delle biomasse. Il presente studio ha avuto come obiettivo la valutazione di Arundo donax L., una specie no food in grado di garantire elevate rese in biomassa, per la produzione di biogas. A questo scopo è stata utilizzata una prova di campo, attiva dal 2006 presso il Centro di Ricerca Inter-Universitario Biomasse da Energia (CRIBE), che ha come obiettivo lo studio dell’effetto dell’epoca di taglio sulla produzione e qualità della biomassa di A. donax. Inoltre, per lo scopo specifico di valutazione della digestione anaerobica nel suo complesso (potenziale metanigeno e caratterizzazione chimica/microbiologica del digestato) è stato utilizzato un digestore sperimentale in batch (a ciclo discontinuo) nel quale è stata digerita la biomassa ottenuta da cinque epoche di taglio di A. donax (A1: 20/06/2011; A2: 15/07/2011; A3: 02/08/2011; A4: 22/08/2011; A5: 20/09/2011), a confronto con Zea mays L. (mais), coltura comunemente utilizzata per la produzione di biogas. La produzione di metano di A. donax in batch è risultata simile al mais e seppure A3 risultava essere il più produttivo in tali condizioni rispetto agli altri tagli, la resa metanigena ad ettaro, stimata sulla base delle rese di campo, ha messo in evidenza che A5 è stato il più efficiente anche rispetto al mais. Per quanto riguarda invece le caratteristiche chimiche dei digestati, il contenuto in N e P era simile tra A. donax e Z. mays, mentre le comunità di archea metanigeni si differenziavano tra le colture. La selezione di colture dedicate no food in grado di valorizzare le aree agricole marginali, come l’A. donax, insieme alla selezione di specie native appartenenti agli archea metanigeni, presentano prospettive interessanti per un futuro utilizzo di questa coltura per la produzione di biogas