Mining for Useful Association Rules Using the ATMS

Association rule mining has made many achievements in the area of knowledge discovery in databases. Recent years, the quality of the extracted association rules has drawn more and more attention from researchers in data mining community. One big concern is with the size of the extracted rule set. Very often tens of thousands of association rules are extracted among which many are redundant thus useless. In this paper, we first analyze the redundancy problem in association rules and then propose a novel ATMS-based method for extracting non-redundant association rules

PSR B1257+12: a quark star with planets?

A recent observation has shown that PSR B1257+12 could have quite small X-ray emitting area, only about 2000 m$^2$, which is more than three orders smaller than the canonical polar cap size. We suggest here that PSR B1257+12 could be a low-mass quark star with radius of $R \simeq 0.6$ km and mass of M \simeq 3\times10^{-4}\msun. Such a low-mass quark star system may form in an accretion induced collapse process or a collision process of two quark stars.Comment: 3 pages, 1figure, poster at the international conference "Astrophysics of Compact Objects" (July 1-7, 2007, Huangshan, China

Smooth densities of the laws of perturbed diffusion processes

Under some regularity conditions on $b$, $\sigma$ and $\alpha$, we prove that the following perturbed stochastic differential equation \begin{equation} X_t=x+\int_0^t b(X_s)ds+\int_0^t \sigma(X_s) dB_s+\alpha \sup_{0 \le s \le t} X_s, \ \ \ \alpha<1 \end{equation} admits smooth densities for all $0 \le t \le t_0$, where $t_0>0$ is some finite number