Knowledge Engineering from Data Perspective: Granular Computing Approach

The concept of rough set theory is a mathematical approach to uncertainly and vagueness in data analysis, introduced by Zdzislaw Pawlak in 1980s. Rough set theory assumes the underlying structure of knowledge is a partition. We have extended Pawlak’s concept of knowledge to coverings. We have taken a soft approach regarding any generalized subset as a basic knowledge. We regard a covering as basic knowledge from which the theory of knowledge approximations and learning, knowledge dependency and reduct are developed

Growth and Business Cycles for the Swedish Economy 1963-1999

This paper consists of two parts. In the first part we carry out a traditional growth accounting exercise for the private business sectors of the Swedish economy. We search for structural breaks during the sample period, using Chow tests, using a dynamic specification of Total Factor Productivity (TFP). In order to facilitate comparisons we compare the results of this study both with other Swedish and international studies. To a large extent we are able to replicate the results of this study with Swedish results. The slow down in TFP growth rates in the 1970s can be identified with the first and second oil shocks in 1973 and 1979. The other structural breaks in the 1990s can be identified with the Swedish Tax Reform (1991), The Granger causality test indicate that the growth rates in investment Granger cause growth rates in TFP for agriculture and financial institutions, real estate and other business, while TFP growth rates in mining and quarrying and manufacturing Granger cause growth rates in investment. The second part of the paper Hodrick-Prescott filter the data and calculate cross correlations of detrended output, hours, investment and TFP at different leads and lags. The results indicate that investment leads TFP for agriculture, hunting forestry and fishing, electricity gas and water, education health and social work. Investment lags TFP for the mining and quarrying and manufacturing companies. The decomposition of TFP into trend and cyclical component historically dates the Swedish business cycle.growth accounting, labour productivity, total factor productivity, growth dynamics,Hodrick-Prescott filtering, leads and lags, new economy

HOW ACCURATE ARE THE SWEDISH FORECASTERS ON GDP-GROWTH,CPI- INFLATION AND UNEMPLOYMENT? (1993-2001)

This study evaluates the performance of the eight most important Swedish domestic forecasters of real GDP-growth, CPI-inflation and unemployment for the sample period 1993-2001. The evaluation is based on the following measures: mean absolute error, the root mean square error, bias and finally directional accuracy. The forecasts are even compared to naive random walk and random walk with drift models. The results indicate that the current forecasts compared to the year ahead forecasts decline over the forecasting horizons as more information becomes available. The results with respect to the directional accuracy indicate that we are equally good/bad in predicting the directional accuracy for all three macro aggregates. According to the comparisons with the naive random walk model six out of seven Swedish CPI-inflation forecasters were outperformed by the naive random walk model. Tests of bias indicate that the Swedish forecasters underestimate GDP-growth and overestimate CPI-inflation and the unemployment rate for the sample period. All the Swedish forecasters have been successful in predicting the downward trend in CPI-inflation and the unemployment rate. The performance of the Swedish domestic forecasters is better using preliminary GDP-growth outcomes than final. The performance for the current year forecasts is better than the year ahead forecasts for all three macro economic variables. Revisions are positively biased. Key words Mean absolute error, root mean square error, directional accuracy, bias, revisions, final respective preliminary outcomes, Theil index, naïve forecastsMEAN ABSOLUTE ERROR, ROOT MEAN SQUARE ERROR, DIRECTIONAL ACCURACY, BIAS, REVISIONS, FINAL RESPECTIVE PRELIMINARY OUTCOMES

Cluster tilted algebras with a cyclically oriented quiver

In association with a finite dimensional algebra A of global dimension two, we consider the endomorphism algebra of A, viewed as an object in the triangulated hull of the orbit category of the bounded derived category, in the sense of Amiot. We characterize the algebras A of global dimension two such that its endomorphism algebra is isomorphic to a cluster-tilted algebra with a cyclically oriented quiver.Furthermore, in the case that the cluster tilted algebra with a cyclically oriented quiver is of Dynkin or extended Dynkin type then A is derived equivalent to a hereditary algebra of the same type.Comment: 14 pages, 8 figure

The Grothendieck group of a cluster category

For the cluster category of a hereditary or a canonical algebra, equivalently for the cluster category of the hereditary category of coherent sheaves on a weighted projective line, we study the Grothendieck group with respect to an admissible triangulated structure.Comment: 21 pages, accepted for publication by JPA