National Research University – Higher School of Economics

About: National Research University – Higher School of Economics is a education organization based out in Moscow, Russia. It is known for research contribution in the topics: Population & Computer science. The organization has 12873 authors who have published 23376 publications receiving 256396 citations.

Revisiting Numerical Pattern Mining with Formal Concept Analysis

Abstract: In this paper, we investigate the problem of mining numerical data in the framework of Formal Concept Analysis. The usual way is to use a scaling procedure --transforming numerical attributes into binary ones-- leading either to a loss of information or of efficiency, in particular w.r.t. the volume of extracted patterns. By contrast, we propose to directly work on numerical data in a more precise and efficient way, and we prove it. For that, the notions of closed patterns, generators and equivalent classes are revisited in the numerical context. Moreover, two original algorithms are proposed and used in an evaluation involving real-world data, showing the predominance of the present approach.

A report on locally conformally Kahler manifolds

Abstract: 1. Locally conformally K¨ahler manifoldsLocally conformally Kahler (LCK) geometry is concerned with complex man-ifolds of complex dimension at least two admitting a Kahler covering with decktransformations acting by holomorphic homotheties with respect to the K¨ahlermetric.We shall usually denote with Mthe LCK manifold, with (J,g) its Hermitianstructure, with Γ → M˜ → Mthe Kahler covering and with ˜ωthe K¨ahler form onthe covering.Directly from the definition, one obtainsthe existence ofan associatedcharacterχ: Γ → R

Hilbert schemes of lines and conics and automorphism groups of Fano threefolds

Abstract: We discuss various results on Hilbert schemes of lines and conics and automorphism groups of smooth Fano threefolds with Picard rank 1. Besides a general review of facts well known to experts, the paper contains some new results, for instance, we give a description of the Hilbert scheme of conics on any smooth Fano threefold of index 1 and genus 10. We also show that the action of the automorphism group of a Fano threefold $X$ of index 2 (respectively, 1) on an irreducible component of its Hilbert scheme of lines (respectively, conics) is faithful if the anticanonical class of $X$ is very ample with a possible exception of several explicit cases. We use these faithfulness results to prove finiteness of the automorphism groups of most Fano threefolds and classify explicitly all Fano threefolds with infinite automorphism group. We also discuss a derived category point of view on the Hilbert schemes of lines and conics, and use this approach to identify some of them.

Decentralization in regional fiscal systems in Russia - trends and links to economic performance

Abstract: Considering the positive impact decentralization has had on regional economic performance and expenditure structure, Russia's federal government should: - Decisively protect local self-governance and budget autonomy. - Make intergovernmental fiscal relations more transparent. - Develop universal models of interactions between regional and municipal governments. - Impose stricter limits on total debt and budget deficits of subnational governments. To shed light on decentralization in Russia, Freinkman and Yossifov examine intergovernmental fiscal relations within regions. To analyze trends, they review channels of fiscal allocation within regions-tax sharing and local transfer schemes. To evaluate the potential impact of various fiscal decentralization patterns on regional economic performance (including growth and the budget deficit), they study data on the structure of 89 Russian consolidated regional budgets for 1992-96. They find that local governments' relative share of Russia's consolidated budget, although substantive (roughly a quarter of the total budget), did not expand after 1994. The federal government's relative role in financing public goods and services declined as the relative role of local governments increased substantially. Local governments collected more revenues in 1996 (6.4 percent of GDP) and spent more than regional governments. They also substantially increased social financing (including health, education, and social protection). Russia made no progress toward a more transparent system for tax assignments. The average level of expenditure decentralization is similar for ethnically Russian regions and national republics and okrugs but revenue arrangements differ greatly. True decentralization has taken place in oblasts and krais, where local authorities are provided with a bigger share of subnational tax revenues. A redistribution model applies in republics and autonomous okrugs, where greater local outlays have been financed through larger transfers from regional governments. Regions near each other tend to have similar budget arrangements - the result of intensive interactions between neighbors and probably supported by the activities of regional associations. The size of a region's territory does not influence decentralization outcomes. Fiscal decentralization seems positively related to the share of education spending in regional budgets. And regions with more decentralized finances tend to experience less economic decline. But budget control is weaker in more decentralized regions. Instability and lack of transparency in intergovernmental fiscal relations provide subnational governments little incentive for responsible fiscal policy. Further decentralization without greater transparency could bring greater debt and deficits. This paper - a product of the Poverty Reduction and Economic Management Sector Unit, Europe and Central Asia Region - is part of a larger effort in the unit to study fiscal decentralization in transition economies. Lev Freinkman may be contacted at lfreinkman@worldbank.org.