Revisiting the cluster-based paradigm for implicit search result diversification

To cope with ambiguous and/or underspecified queries, search result diversification (SRD) is a key technique that has attracted a lot of attention. This paper focuses on implicit SRD, where the subtopics underlying a query are unknown. Many existing methods appeal to the greedy strategy for generating diversified results. A common practice is using a heuristic criterion for making the locally optimal choice at each round. As a result, it is difficult to know whether the failures are caused by the optimization criterion or the setting of parameters. Different from previous studies, we formulate implicit SRD as a process of selecting and ranking k exemplar documents through integer linear programming (ILP). The key idea is that: for a specific query, we expect to maximize the overall relevance of the k exemplar documents. Meanwhile, we wish to maximize the representativeness of the selected exemplar documents with respect to the non-selected documents. Intuitively, if the selected exemplar documents concisely represent the entire set of documents, the novelty and diversity will naturally arise. Moreover, we propose two approaches ILP4ID (Integer Linear Programming for Implicit SRD) and AP4ID (Affinity Propagation for Implicit SRD) for solving the proposed formulation of implicit SRD. In particular, ILP4ID appeals to the strategy of bound-and-branch and is able to obtain the optimal solution. AP4ID being an approximate method transforms the target problem as a maximum-a-posteriori inference problem, and the message passing algorithm is adopted to find the solution. Furthermore, we investigate the differences and connections between the proposed models and prior models by casting them as different variants of the cluster-based paradigm for implicit SRD. To validate the effectiveness and efficiency of the proposed approaches, we conduct a series of experiments on four benchmark TREC diversity collections. The experimental results demonstrate that: (1) The proposed methods, especially ILP4ID, can achieve substantially improved performance over the state-of-the-art unsupervised methods for implicit SRD. (2) The initial runs, the number of input documents, query types, the ways of computing document similarity, the pre-defined cluster number and the optimization algorithm significantly affect the performance of diversification models. Careful examinations of these factors are highly recommended in the development of implicit SRD methods. Based on the in-depth study of different types of methods for implicit SRD, we provide additional insight into the cluster-based paradigm for implicit SRD. In particular, how the methods relying on greedy strategies impact the performance of implicit SRD, and how a particular diversification model should be fine-tuned.     

关于丛书、多卷书著录规则的探讨

丛书、多卷书的著录方式存在争议,本文就其原因进行了分析,并提出了减少争议的办法。     

时间序列数据挖掘在医疗领域的应用

医院信息管理系统,不仅有利于提高了医务工作者的工作效率,同时也积累了大量的时间序列数据。时间序列数据挖掘技术对这些大量数据进行分析,会发现有用的、潜在的知识为开展高水平医学研究提供了有力的技术工具。对历史数据进行分析的同时能预测出未来的相关数据,为医院管理人员作出正确决策提供了依据。因此对医院信息系统中时间序列数据挖掘的过程以及所应用的技术深入研究,能充分发挥数据挖掘在医疗领域的作用。     

《民国诗话丛编》校点抉疵

《民国诗话丛编》作为古籍整理的一大工程,彰幽拯湮,功不可没。但在校点尤其是标点方面也存在一些失误,如人名、地名、书名的误标漏标,以及断句不当、文字讹误等。本文抉取其尤,分类条列指说,以期同行重视。     

关于Directly-Riemann积分的Riemann定理的推广

在Fourier级数的收敛理论中 ,Riemann引理 (Riemann积分意义下 )起到了非常重要的作用 .在Directly_Riemann积分意义下 ,给出了Riemann定理 .即设f(x) ,g(x)是定义在 [0 ,+∞ )上非负 (D_R)可积函数 ,｜g(x)｜≤M ,对任意的区间 [0 ,A] [0 ,+∞ ) ,有∫A0g(x)dx ≤k ,则limp→+∞∫+∞0 f(x)g(px)dx =0 .     

Xn+Yn=Zn n≥3时无整数解

本文利用首创的互补开方法,来证明此定理。     

一种Kummer类型的微分方程及其严格解

以级数展开的方法，严格求解了一个二阶变系数微分方程，讨论了解函数的对称性及其收敛性，通过与已知的其他特殊函数的比较发现，运用适当的变量代换，方程的解可用已知的合流超几何函数来表示。并且在此代换下，此微分方程的确可变换为Kummer方程。     

乘积季节模型在能源生产量预测中的应用

本文使用乘积季节模型,对1999年到2005年全国能源生产总量进行分析,给出乘积季节模型的一般建模程序。根据Box-Jenkins的建模思想,从各种指标最终确定模型(0,1,1)×(0,1,1)12,该模型显示了非常好的拟合及预测效果。     

中国地学期刊的国际化思考 ——以Science in China Series D: Earth Sciences为例

通过对比Science in China Series D:Earth Sciences(简称SCES)与Journal of Geophysical Research(简称JGR)、Geophysical Research Letters(简称GRL)和Journal of Asian Earth Sciences(简称JAES)3个国际地学期刊的国际化程度,结合SCES的地域性特点、中国地学研究的发展与国际合作程度以及笔者的工作实际,提出SCES的国际化必须是立足本土的国际化,目前亟待解决的是读者的国际化,并呼吁期刊管理部门制定评价指标时,考虑SCES类期刊地域性的特点.     

浅谈丛书、多卷书的分类问题

根据丛书、多卷书的定义、特点,总结出丛书、多卷书的分类方法,即丛书分类以"分散处理"为主,"集中处理"为辅,多卷书分类以"集中归类"为主,"分析分类"为辅.