Succinct Filters for Sets of Unknown Sizes

The membership problem asks to maintain a set S ? [u], supporting insertions and membership queries, i.e., testing if a given element is in the set. A data structure that computes exact answers is called a dictionary. When a (small) false positive rate ? is allowed, the data structure is called a filter. The space usages of the standard dictionaries or filters usually depend on the upper bound on the size of S, while the actual set can be much smaller. Pagh, Segev and Wieder [Pagh et al., 2013] were the first to study filters with varying space usage based on the current |S|. They showed in order to match the space with the current set size n = |S|, any filter data structure must use (1-o(1))n(log(1/?)+(1-O(?))log log n) bits, in contrast to the well-known lower bound of N log(1/?) bits, where N is an upper bound on |S|. They also presented a data structure with almost optimal space of (1+o(1))n(log(1/?)+O(log log n)) bits provided that n > u^0.001, with expected amortized constant insertion time and worst-case constant lookup time. In this work, we present a filter data structure with improvements in two aspects: - it has constant worst-case time for all insertions and lookups with high probability; - it uses space (1+o(1))n(log (1/?)+log log n) bits when n > u^0.001, achieving optimal leading constant for all ? = o(1). We also present a dictionary that uses (1+o(1))nlog(u/n) bits of space, matching the optimal space in terms of the current size, and performs all operations in constant time with high probability

Estudio comparativo de algunas construcciones impersonales en español y chino

El objetivo de esta tesis doctoral es hacer una investigación contrastiva entre español y chino, sobre dos tipos de oraciones: oraciones con predicados de fenómenos naturales, por un lado y, oraciones con predicados de existencia y de aparición y desaparición, por otro. Tanto en chino como en español, estos dos tipos de oraciones han sido analizados como oraciones impersonales, u oraciones sin sujeto. Sin embargo, existen otras formas posibles de aproximarse a su análisis ya que se pueden considerar oraciones que también tienen sujetos, aunque sean sujetos menos convencionales. Las intrincadas propiedades del concepto de sujeto han suscitado en mí el interés por realizar un estudio sobre esta función sintáctica y para ello me he centrado en dos tipos de oraciones impersonales prototípicas..

Research on Digital Transformation of Financial Industry under the Influence of COVID-19 Epidemic

In the prevention and control of epidemic situation in COVID-19, a large number of Internet companies actively use big data to analyze and display epidemic situation, providing important support for orderly resumption of work and production while preventing and controlling epidemic situation. The epidemic situation has promoted the continuous emergence of various online services, ensured the basic needs of people’s life and study, brought vitality to the real economy, and at the same time gave birth to a number of new formats and models of digital economy. The growth of the digital economy itself is also greatly affected by the epidemic, and different formats are affected to varying degrees. During the epidemic, banking institutions made full use of the digital transformation achievements in recent years, innovated financial service methods through various online financial service platforms, and enriched online and offline collaborative products and service systems. This paper mainly discusses the problems and development strategies of digital transformation of financial industry under the influence of COVID-19 epidemic

Empirical Analysis of X-efficiency and Profitability of Commercial Banks in Canada

This paper will examine the efficiency and profitability of Canadian banking sector. The idea is to take a two-stage approach to test determinants of profitability over the period of 2010-2016 with respect to bank’s efficiency performance. In the first stage, the model will be focused on estimations using Stochastic Frontier Analysis (SFA) of cost functions to get the efficiency score for Canadian banks. Then in the second stage, estimations using Generalized Method of Moments (GMM) will be modeled to find out the significant variables influencing bank’s profitability, along with consideration of the efficiency score from the first stage and calculated Z score along with internal and external variables. Results indicate that efficiency has positive and significant impact on bank’s profitability, while Z score and other factors demonstrate mixed effects

Examining tax revenue losses from the C2C mode of electronic commerce in China

This paper started with the basic concepts of e-commerce and tax revenue and adopted the methods of econometrics in attempts to prove the existence of the tax loss of C2C e-commerce mode and elaborate the tax loss degree. The issue of tax in C2C e-commerce mode was explored through the conductive process of the impacts of C2C mode on tax revenue in the research, wherein it selected the proportion of C2C scale in the total retail sales of consumer goods as the index measuring the development condition of C2C e-commerce, chose the tax revenue as the index quantifying the tax development, meanwhile selected the total retail sales of consumer goods and the total amount of online retail shopping as the index quantifying the retail industry of real economy and had a conduction effect. In this paper, the influence degree of the online retail shopping of C2C e-commerce on retail price index through establishing was explored and the measurement model for the proportions of retail price index and C2C limit in the total retail sales of consumer goods was analyzed to work out the influence degree of online retail shopping of C2C e-commerce on the tax through the positive correlation between retail price index and tax revenue. The research results (multiple regression analysis) showed that when the proportion of C2C limit in total retail sales of consumer goods increased 1%, the tax revenue would decrease RMB 0.1310908 trillion. It could be seen that the tax loss, value of import and export, and the business volume under C2C mode had obvious impacts on the total tax amount. The null hypothesis was rejected and the alternative assumptions were approved. In other words, there was a linear relationship between dependent variables and independent variables. The research shed some light on tax loss issues in China under the mode of C2C. With a combination of qualitative analysis, tax administration theory, empirical measurement analysis results and foreign experiences, the prevention solution to the tax loss issue of Chinese e-commerce and primary policy suggestions about the tax loss of Chinese domestic e-commerce were proposed in this paper. As a typical country under the commercial mode of C2C, tax loss issues in China were analyzed for reference of other countries