327 research outputs found
A Network Analysis of Countries’ Export Flows: Firm Grounds for the Building Blocks of the Economy
No full textIn this paper we analyze the bipartite network of countries and products from UN data on country production. We define the country-country and product-product projected networks and introduce a novel method of filtering information based on elements’ similarity. As a result we find that country clustering reveals unexpected socio-geographic links among the most competing countries. On the same footings the products clustering can be efficiently used for a bottom-up classification of produced goods. Furthermore we mathematically reformulate the “reflections method” introduced by Hidalgo and Hausmann as a fixpoint problem; such formulation highlights some conceptual weaknesses of the approach. To overcome such an issue, we introduce an alternative methodology (based on biased Markov chains) that allows to rank countries in a conceptually consistent way. Our analysis uncovers a strong non-linear interaction between the diversification of a country and the ubiquity of its products, thus suggesting the possible need of moving towards more efficient and direct non-linear fixpoint algorithms to rank countries and products in the global market.</p
Treewidth: a useful marker of empirical hardness in quantified Boolean logic encodings
No full textTheoretical studies show that in some combinatorial problems, there is a close relationship between classes of tractable instances and the treewidth (tw) of graphs describing their structure. In the case of satisfiability for quantified Boolean formulas (QBFs), tractable classes can be related to a generalization of treewidth, that we call quantified treewidth (tw p). In this paper we investigate the practical relevance of computing tw p) for problem domains encoded as QBFs. We show that an approximation of tw p is a predictor of empirical hardness, and that it is the only parameter among several other candidates which succeeds consistently in being so. We also provide evidence that QBF solvers benefit from a preprocessing phase geared towards reducing tw p, and that such phase is a potential enabler for the solution of hard QBF encodings
SAT vs. Translation Based decision procedures for modal logics: a comparative evaluation
No full textThis paper follows on previous papers which present and evaluate various decision procedures for modal logics. It confirms previous experimental results in showing that SAT based decision procedures, i.e., the procedures built on top of decision procedures for propositional satisfiability, are more efficient than tableau based decision procedures. It also confirms previous evidence of an easy-hard-easy pattern in the satisfiability curve for modal K. Finally, it provides further experimental results, suggesting that SAT based decision procedures are also more efficient than the decision procedures based on translation methods. These results contradict some of the claims presented in previous papers by other author
Derivative lymphatic microsurgery: indications, techniques, and results.
No full textMicrosurgical derivative procedures to treat chronic lymphedemas of the limbs are reported here. Techniques used consisted of lymphatic capsule- venous anastomoses (in pediatric patients) and end-to-side lymphatic-venous anastomoses. Results after more than 5 years showed improvement in about 70% of the cases. The importance of an accurate preoperative diagnostic evaluation and the precise indications for these microsurgical procedures are discussed. Some personal modifications of derivative microsurgical techniques and their advantages are also pointed out
Trans P Art transparent postal art for Jochen Gerz : registrato 22 Ago. 1978, spedito 26 Ago. 1978
No full text
OT cyber security frameworks comparison tool (CSFCTool)
No full textThis paper proposes a holistic cybersecurity online tool to support implementation activities of the “National Framework for Cybersecurity & Data Protection”, one of its contextualizations, as well as the fifteen “Essential Cybersecurity Controls”. It also aims at promoting its wide dissemination by SMEs. All the regulations, standards and national/international laws mentioned as “Informative References” for each Subcategory in the Framework Core are, in fact, made available through a web application where they can be consulted with a few clicks, guiding even less experienced users in the creation of their cybersecurity compliance projects. The research and analysis activities conducted with a systematic, global and conceptual approach - consistent with the original document - have been aimed at highlighting the substantial differences between IT/OT cybersecurity requirements in order to increase, through a comparative analysis, the cyber resilience of national critical infrastructures. Meanwhile, since an important step towards cyberspace security is a global increase in the level of cyber risk awareness, the tool aims to be used for education and training programs too, both at the corporate and academic levels, in order to bridge the skills gap in the job market between job seekers and employers. For this purpose, some of the main reference standards used for auditing, vulnerability assessment and risk management activities have been included
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