9602783
Discovery of interesting association rules from Livelink web log data
We present our experience in mining web usage patterns from a large collection of Livelink log data. Livelink is a web-based product of Open Text, which provides automatic management and retrieval of different types of information objects over an intranet or extranet. We report our experience in preprocessing raw log data and post-processing the mining results for finding interesting rules. In particular we compare and evaluate a number of rule interestingness measures and find that two of the measures that have not been used in association rule learning work very well.
27390518
Session Boundary Detection for Association Rule Learning Using n-Gram Language Models
We present a statistical method using n-gram language models to identify session boundaries in a large collection of Livelink log data. The identified sessions are then used for association rule learning. Unlike the traditional ad hoc timeout method, which uses fixed time thresholds for session identification, our method uses an information theoretic approach that provides a natural technique for performing dynamic session identification. The effectiveness of our approach is evaluated with respect to 4 different interestingness measures. We find that we obtain a significant improvement in each interestingness measure, ranging from a 26.6% to 39% improvement on average over the best results obtained with standard timeout methods.
11235220
Probability-Based Chinese Text Processing and Retrieval
We discuss the use of probability-based natural language processing for Chinese text retrieval. We focus on comparing different text extraction methods and probabilistic weighting methods. Several docu- ment processing methods and probabilistic weighting functions are presented. A number of experiments have been conducted on large standard text collections. We present the experimental results that com- pare a word-based text processing method with a character-based method. The experimental results also compare a number of term-weighting functions including both single-unit weighting and compound-unit weighting functions. Modern information retrieval (IR) systems should be able to take natural language queries and retrieve documents written in natural languages. One way to process nat- ural language texts in IR is statistical. In this approach, linguistic units are extracted from the documents and queries. Those units extracted from the documents are used to index the documents. Those extracted from a query are weighted according to their degrees of importance. The most important units are chosen as query terms. An infor- mation retrieval system takes the selected query terms, matches the terms with the indexes of documents, calculates a retrieval status value for each matched document using a term-weighting method, and presents the user with potentially relevant docu- ments from a collection of documents. The performance of the information retrieval system in identifying relevant documents greatly depends on the text processing method used. We investigate the effectiveness of different text extraction methods and different term weighting methods in the context of Chinese information retrieval. It is a well- known problem that there is no separator between Chinese words, so Chinese words cannot be used easily to index or search texts as is possible in English. Therefore, some people use characters or n-grams as searchable tokens instead of words. We discuss two text extraction methods. One extraction method uses words, compound words, and phrases in the document and query texts as indexing terms to represent the texts. We refer to this method as the word-based approach. For this approach, text segmentation, which divides both document and query texts into linguistic units, is regarded not only as a necessary precursor but also as a bottleneck of this kind of system (Wu and Tseng 1993). The other extraction method is based on single Chinese characters, in which texts are indexed by the characters appearing in the texts (Chen 1992). By using sin- gle character approaches, a search could be conducted for any multi-character word or phrase identified at search time, no matter whether this word or phrase is in the dic- tionary. Both word-based and character-based methods have been used in information
410602
Using self-supervised word segmentation in Chinese information retrieval
We propose a self-supervised word-segmentation technique for Chinese information retrieval. This method combines the advantages of traditional dictionary based approaches with character based approaches, while overcoming many of their shortcomings. Experiments on TREC data show comparable performance to both the dictionary based and the character based approaches. However, our method is language independent and unsupervised, which provides a promising avenue for constructing accurate multilingual information retrieval systems that are flexible and adaptive.
14449557
Evaluation and automatic selection of methods for handling missing data
Real-world data often contain missing values. In this paper, nine different methods for handling missing data are described and compared. Thirty real-world datasets are used as input data in our experiment. Nine different missing levels are implemented in each training data set to investigate the performance of the methods at different missing levels. For evaluation, two different classification techniques, C4.5 and ELEM2, are applied to obtain the classification error rates. The experimental results show that different methods can have different effects on a data set. Based on the experimental results, we also propose a meta-learning approach to selecting a method for handling missing data. The evaluation results show that the meta-learning approach is effective in selecting a suitable method for handling missing data.
921552
Dynamic Web log session identification with statistical language models
We present a novel session identification method based on statistical language modeling. Unlike standard time-out methods, which use fixed time thresholds for session identification, we use an information theoretic approach that yields more robust results for identifying session boundaries. We evaluate our new approach by learning interesting association rules from the segmented session files. We then compare the performance of our approach to three standard session identification method--the standard timeout method, the reference length method, and the maximal forward reference method--and find that our statistical language modeling approach generally yields superior results. However, as with every method, the performance of our technique varies with changing parameter settings. Therefore, we also analyze the influence of the two key factors in our language-modeling-based approach: the choice of smoothing technique and the language model order. We find that all standard smoothing techniques, save one, perform well, and that performance is robust to language model order.
16444798
Finding Similar Patterns in Microarray Data
In this paper we propose a clustering algorithm called s-Cluster for analysis of gene expression data based on pattern-similarity. The algorithm captures the tight clusters exhibiting strong similar expression patterns in Microarray data,and allows a high level of overlap among discovered clusters without completely grouping all genes like other algorithms. This reflects the biological fact that not all functions are turned on in an experiment, and that many genes are co-expressed in multiple groups in response to different stimuli. The experiments have demonstrated that the proposed algorithm successfully groups the genes with strong similar expression patterns and that the found clusters are interpretable.
6321735
In-Route Skyline Querying for Location-Based Services
With the emergence of an infrastructure for location-aware mobile services, the processing of advanced, location-based queries that are expected to underlie such services is gaining in relevance. While much work has assumed that users move in Euclidean space, this paper assumes that movement is constrained to a road network and that points of interest can be reached via the network. More specifically, the paper assumes that the queries are issued by users moving along routes towards destinations. The paper defines in-route nearest-neighbor skyline queries in this setting and considers their efficient computation. The queries take into account several spatial preferences, and they intuitively return a set of most interesting results for each result returned by the corresponding non-skyline queries. The paper also covers a performance study of the proposed techniques based on real point-of-interest and road network data.
18862916
Clustering graphs for visualization via node similarities
Graph visualization is commonly used to visually model relations in many areas. Examples include Web sites, CASE tools, and knowledge representation. When the amount of information in these graphs becomes too large, users, however, cannot perceive all elements at the same time. A clustered graph can greatly reduce visual complexity by temporarily replacing a set of nodes in clusters with abstract nodes. This paper proposes a new approach to clustering graphs. The approach constructs the node similarity matrix of a graph that is derived from a novel metric of node similarity. The linkage pattern of the graph is thus encoded into the similarity matrix, and then one obtains the hierarchical abstraction of densely linked subgraphs by applying the k-means algorithm to the matrix. A heuristic method is developed to overcome the inherent drawbacks of the k-means algorithm. For clustered graphs we present a multilevel multi-window approach to hierarchically drawing them in different abstract level views with the purpose of improving their readability. The proposed approaches demonstrate good results in our experiments. As application examples, visualization of part of Java class diagrams and Web graphs are provided. We also conducted usability experiments on our algorithm and approach. The results have shown that the hierarchically clustered graph used in our system can improve user performance for certain types of tasks.
121152
Dynamic programming algorithms for restriction map comparison
For most sequence comparison problems there is a corresponding map comparison algorithm. While map data may appear to be incompatible with dynamic programming, we show in this paper that the rigor and efficiency of dynamic programming algorithms carry over to the map comparison algorithms. We present algorithms for restriction map comparison that deal with two types of map errors: (i) closely spaced sites for different enzymes can be ordered incorrectly, and (ii) closely spaced sites for the same enzyme can be mapped as a single site. The new algorithms are a natural extension of a previous map comparison model. Dynamic programming algorithms for computing optimal global and local alignments under the new model are described. The new algorithms take about the same order of time as previous map comparison algorithms. Programs implementing some of the new algorithms are used to find similar regions within the Escherichia coli restriction map of Kohara et al.
5775998
Identification of clusters in the Web graph based on link topology
The Web graph has recently been used to model the link structure of the Web. The studies of such graphs can yield valuable insights into Web algorithms for crawling, searching and discovery of Web communities. This paper proposes a new approach to clustering the Web graph. The proposed algorithm identifies a small subset of the graph as "core" members of clusters, and then incrementally constructs the clusters by a selection criterion. Two qualitative criteria are proposed to measure the quality of graph clustering. We have implemented our algorithm and tested a set of arbitrary graphs with good results. Applications of our approach include graph drawing and Web visualization.