Hypergraph Clustering Research Articles

Optimized Hypergraph Clustering-based Network Security Log Mining*

With network's growth and popularization, network security experts are facing bigger and bigger network security log. Network security log is a kind of valuable and important information recording various network behaviors, and has the features of large-scale and high dimension. Therefore, how to analyze these network security log to enhance the security of network becomes the focus of many researchers. In this paper, we first design a frequent attack sequencebased hypergraph clustering algorithm to mine the network security log, and then improve this algorithm with a synthetic measure of hyperedge weight and two optimization functions of clustering result. The experimental results show that the synthetic measure and optimization functions can promote significantly the coverage and precision of clustering result. The optimized hypergraph clustering algorithm provides a data analyzing method for intrusion detecting and active forewarning of network.

SafeChoice: A Novel Approach to Hypergraph Clustering for Wirelength-Driven Placement

This paper presents a completely new approach to the problem of hypergraph clustering for wirelength-driven placement. The novel algorithm we propose is called SafeChoice (SC). Different from all previous approaches, SC is proposed based on a fundamental theorem, safe condition which guarantees that clustering would not degrade the placement wirelength. To mathematically derive such a theorem, we first introduce the concept of safe clustering, i.e., do clustering without degrading the placement quality. To efficiently check the safe condition for pair-wise clustering, we propose a technique called selective enumeration. SafeChoice maintains a global priority queue based on the safeness and area of potential clusters. Using a simple heuristic, it automatically stops clustering when generating more clusters would degrade the placement wirelength. Moreover, we extend SafeChoice to do clustering while considering the object physical locations, i.e., physical clustering. Finally, we apply SafeChoice into a two-phase placement framework and propose a high-quality analytical placement algorithm called SCPlace. Comprehensive experimental results show that the clusters produced by SC consistently help the placer to achieve the best wirelength among all other clustering algorithms, and SCPlace generates the best half-perimeter wirelength compared with all other state-of-the-art placers.

Multiple hypergraph clustering of web images by mining Word2Image correlations

In this paper, we consider the problem of clustering Web images by mining correlations between images and their corresponding words. Since Web images always come with associated text, the corresponding textual tags of Web images are used as a source to enhance the description of Web images. However, each word has different contribution for the interpretation of image semantics. Therefore, in order to evaluate the importance of each corresponding word of Web images, we propose a novel visibility model to compute the extent to which a word can be perceived visually in images, and then infer the correlation of word to image by the integration of visibility with tf-idf. Furthermore, Latent Dirichlet Allocation (LDA) is used to discover topic information inherent in surrounding text and topic correlations of images could be defined for image clustering. For integrating visibility and latent topic information into an image clustering framework, we first represent textual correlated and latent-topic correlated images by two hypergraph views, and then the proposed Spectral Multiple Hypergraph Clustering (SMHC) algorithm is used to cluster images into categories. The SMHC could be regarded as a new unsupervised learning process with two hypergraphs to classify Web images. Experimental results show that the SMHC algorithm has better clustering performance and the proposed SMHC-based image clustering framework is effective.

Multiple Hypergraph Clustering of Web Images by MiningWord2Image Correlations

Multiple Hypergraph Clustering of Web Images by MiningWord2Image Correlations

Dissecting trait heterogeneity: a comparison of three clustering methods applied to genotypic data

BackgroundTrait heterogeneity, which exists when a trait has been defined with insufficient specificity such that it is actually two or more distinct traits, has been implicated as a confounding factor in traditional statistical genetics of complex human disease. In the absence of detailed phenotypic data collected consistently in combination with genetic data, unsupervised computational methodologies offer the potential for discovering underlying trait heterogeneity. The performance of three such methods – Bayesian Classification, Hypergraph-Based Clustering, and Fuzzy k-Modes Clustering – appropriate for categorical data were compared. Also tested was the ability of these methods to detect trait heterogeneity in the presence of locus heterogeneity and/or gene-gene interaction, which are two other complicating factors in discovering genetic models of complex human disease. To determine the efficacy of applying the Bayesian Classification method to real data, the reliability of its internal clustering metrics at finding good clusterings was evaluated using permutation testing.ResultsBayesian Classification outperformed the other two methods, with the exception that the Fuzzy k-Modes Clustering performed best on the most complex genetic model. Bayesian Classification achieved excellent recovery for 75% of the datasets simulated under the simplest genetic model, while it achieved moderate recovery for 56% of datasets with a sample size of 500 or more (across all simulated models) and for 86% of datasets with 10 or fewer nonfunctional loci (across all simulated models). Neither Hypergraph Clustering nor Fuzzy k-Modes Clustering achieved good or excellent cluster recovery for a majority of datasets even under a restricted set of conditions. When using the average log of class strength as the internal clustering metric, the false positive rate was controlled very well, at three percent or less for all three significance levels (0.01, 0.05, 0.10), and the false negative rate was acceptably low (18 percent) for the least stringent significance level of 0.10.ConclusionBayesian Classification shows promise as an unsupervised computational method for dissecting trait heterogeneity in genotypic data. Its control of false positive and false negative rates lends confidence to the validity of its results. Further investigation of how different parameter settings may improve the performance of Bayesian Classification, especially under more complex genetic models, is ongoing.

Hypergraph Models and Algorithms for Data-Pattern-Based Clustering

In traditional approaches for clustering market basket type data, relations among transactions are modeled according to the items occurring in these transactions. However, an individual item might induce different relations in different contexts. Since such contexts might be captured by interesting patterns in the overall data, we represent each transaction as a set of patterns through modifying the conventional pattern semantics. By clustering the patterns in the dataset, we infer a clustering of the transactions represented this way. For this, we propose a novel hypergraph model to represent the relations among the patterns. Instead of a local measure that depends only on common items among patterns, we propose a global measure that is based on the cooccurences of these patterns in the overall data. The success of existing hypergraph partitioning based algorithms in other domains depends on sparsity of the hypergraph and explicit objective metrics. For this, we propose a two-phase clustering approach for the above hypergraph, which is expected to be dense. In the first phase, the vertices of the hypergraph are merged in a multilevel algorithm to obtain large number of high quality clusters. Here, we propose new quality metrics for merging decisions in hypergraph clustering specifically for this domain. In order to enable the use of existing metrics in the second phase, we introduce a vertex-to-cluster affinity concept to devise a method for constructing a sparse hypergraph based on the obtained clustering. The experiments we have performed show the effectiveness of the proposed framework.