Robert Kitt

Bio: Robert Kitt is an academic researcher from Tallinn University of Technology. The author has contributed to research in topics: Complex network & Business ethics. The author has an hindex of 4, co-authored 19 publications receiving 76 citations. Previous affiliations of Robert Kitt include Swedbank.

On the topologic structure of economic complex networks: Empirical evidence from large scale payment network of Estonia

Abstract: This paper presents the first topological analysis of the economic structure of an entire country based on payments data obtained from Swedbank. This data set is exclusive in its kind because around 80% of Estonia's bank transactions are done through Swedbank; hence, the economic structure of the country can be reconstructed. Scale-free networks are commonly observed in a wide array of different contexts such as nature and society. In this paper, the nodes are comprised by customers of the bank (legal entities) and the links are established by payments between these nodes. We study the scaling-free and structural properties of this network. We also describe its topology, components and behaviors. We show that this network shares typical structural characteristics known in other complex networks: degree distributions follow a power law, low clustering coefficient and low average shortest path length. We identify the key nodes of the network and perform simulations of resiliency against random and targeted attacks of the nodes with two different approaches. With this, we find that by identifying and studying the links between the nodes is possible to perform vulnerability analysis of the Estonian economy with respect to economic shocks.

Fractal and multifractal analysis of complex networks: Estonian network of payments

Abstract: Complex networks have gained much attention from different areas of knowledge in recent years. Particularly, the structures and dynamics of such systems have attracted considerable interest. Complex networks may have characteristics of multifractality. In this study, we analyze fractal and multifractal properties of a novel network: the large scale economic network of payments of Estonia, where companies are represented by nodes and the payments done between companies are represented by links. We present a fractal scaling analysis and examine the multifractal behavior of this network by using a sandbox algorithm. Our results indicate the existence of multifractality in this network and consequently, the existence of multifractality in the Estonian economy. To the best of our knowledge, this is the first study that analyzes multifractality of a complex network of payments.

Scaling analysis of multi-variate intermittent time series

Abstract: The scaling properties of the time series of asset prices and trading volumes of stock markets are analysed. It is shown that similar to the asset prices, the trading volume data obey multi-scaling length-distribution of low-variability periods. In the case of asset prices, such scaling behaviour can be used for risk forecasts: the probability of observing next day a large price movement is (super-universally) inversely proportional to the length of the ongoing low-variability period. Finally, a method is devised for a multi-factor scaling analysis. We apply the simplest, two-factor model to equity index and trading volume time series.

Fractal and multifractal analysis of complex networks: Estonian network of payments

Abstract: Complex networks have gained much attention from different areas of knowledge in recent years. Particularly, the structures and dynamics of such systems have attracted considerable interest. Complex networks may have characteristics of multifractality. In this study, we analyze fractal and multifractal properties of a novel network: the large scale economic network of payments of Estonia, where companies are represented by nodes and the payments done between companies are represented by links. We present a fractal scaling analysis and examine the multifractal behavior of this network by using a sandbox algorithm. Our results indicate the existence of multifractality in this network and consequently, the existence of multifractality in the Estonian economy. To the best of our knowledge, this is the first study that analyzes multifractality of a complex network of payments.

Probability of large movements in financial markets

Abstract: Based on empirical financial time series, we show that the “silence-breaking” probability follows a super-universal power law: the probability of observing a large movement is inversely proportional to the length of the on-going low-variability period . Such a scaling law has been previously predicted theoretically [R. Kitt, J. Kalda, Physica A 353 (2005) 480], assuming that the length-distribution of the low-variability periods follows a multi-scaling power law.

Random graphs

Abstract: We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

The journal of political economy

Abstract: r 9HE purpose of this paper is to explore a hypothesis, based on acIcumulating evidence, regarding the character of inventions likely to issue from the research laboratories of the large industrial corporations. Simply put, this hypothesis may be stated as follows: with few exceptions, the large industrial laboratories are likely to be minor sources of major (radically new and commercially or militarily important) inventions; rather they are likely to be major sources of essentially "improvement" inventions. Put more precisely, the hypothesis states that the proportion of all minor inventions originating in the large industrial laboratories is likely to exceed the proportion of all major inventions originating in these laboratories. Note that the stress on the relative importance of these laboratories as sources of improvement inventions is not necessarily a denigration of the economic importance of this contribution. The cumulative effect of these improvement inventions may be, and often has been, of substantial importance over long periods of time for advancing technology, investment opportunities, and economic growth. The stress on improvement inventions as the principal product of the research laboratories of the large industrial corporations is meant simply to emphasize that, whatever the importance of their contributions, most of the latter is not likely to involve radically new inventive activity. I cannot claim originality for this hypothesis. After it suggested itself in the course of my investigations, I discovered that others, some of them in the most unlikely positions,2 had earlier said much the same thing. But, apart from occasional remarks, I can find no discussions attempting to explain or justify it. And because, if reasonably accurate, it has numerous ramifications, I have felt the need to set down an extended analysis of 1 I wish to thank members of the Seminar on Law and Technology, sponsored by the University of Wisconsin Law School under the auspices of the Ford Foundation, for their many helpful comments on this paper. Especially do I wish to thank Professors Jacob Schmookler, Robert Merrill, John Stedman, Harrison White, and John Heath. 2 See particularly the statement quoted below (p. 114) of D)r. Frank Jewett, former president of Bell Laboratories.

The European Physical Journal D

Abstract: EPJ E publishes papers describing advances in the understanding of physical aspects of Soft Matter and Biological Systems. The journal includes reports of experimental, computational and theoretical studies and appeals to the broad interdisciplinary communities including physics, chemistry, biology, mathematics and materials science. Unique features of EPJ E: Tips and tricks short papers focused on a novel methodological approach that enables new science Colloquia papers reviewing new directions in Research Prestigious international board of editors Highly competent and fast editorial handling Global contributions and global readership Commonly used title abbreviations: Eur. Phys. J. E, Eur.Phys.J.E, EPJE, EPJ E