2,408 research outputs found
An evolutionary model to mine high expected utility patterns from uncertain databases
In recent decades, mobile or the Internet of Thing (IoT) devices are dramatically increasing in many domains and applications. Thus, a massive amount of data is generated and produced. Those collected data contain a large amount of interesting information (i.e., interestingness, weight, frequency, or uncertainty), and most of the existing and generic algorithms in pattern mining only consider the single object and precise data to discover the required information. Meanwhile, since the collected information is huge, and it is necessary to discover meaningful and up-to-date information in a limit and particular time. In this paper, we consider both utility and uncertainty as the majority objects to efficiently mine the interesting high expected utility patterns (HEUPs) in a limit time based on the multi-objective evolutionary framework. The benefits of the designed model (called MOEA-HEUPM) can discover the valuable HEUPs without pre-defined threshold values (i.e., minimum utility and minimum uncertainty) in the uncertain environment. Two encoding methodologies are also considered in the developed MOEA-HEUPM to show its effectiveness. Based on the developed MOEA-HEUPM model, the set of non-dominated HEUPs can be discovered in a limit time for decision-making. Experiments are then conducted to show the effectiveness and efficiency of the designed MOEA-HEUPM model in terms of convergence, hypervolume and number of the discovered patterns compared to the generic approaches.acceptedVersio
Corporate Smart Content Evaluation
Nowadays, a wide range of information sources are available due to the
evolution of web and collection of data. Plenty of these information are
consumable and usable by humans but not understandable and processable by
machines. Some data may be directly accessible in web pages or via data feeds,
but most of the meaningful existing data is hidden within deep web databases
and enterprise information systems. Besides the inability to access a wide
range of data, manual processing by humans is effortful, error-prone and not
contemporary any more. Semantic web technologies deliver capabilities for
machine-readable, exchangeable content and metadata for automatic processing
of content. The enrichment of heterogeneous data with background knowledge
described in ontologies induces re-usability and supports automatic processing
of data. The establishment of “Corporate Smart Content” (CSC) - semantically
enriched data with high information content with sufficient benefits in
economic areas - is the main focus of this study. We describe three actual
research areas in the field of CSC concerning scenarios and datasets
applicable for corporate applications, algorithms and research. Aspect-
oriented Ontology Development advances modular ontology development and
partial reuse of existing ontological knowledge. Complex Entity Recognition
enhances traditional entity recognition techniques to recognize clusters of
related textual information about entities. Semantic Pattern Mining combines
semantic web technologies with pattern learning to mine for complex models by
attaching background knowledge. This study introduces the afore-mentioned
topics by analyzing applicable scenarios with economic and industrial focus,
as well as research emphasis. Furthermore, a collection of existing datasets
for the given areas of interest is presented and evaluated. The target
audience includes researchers and developers of CSC technologies - people
interested in semantic web features, ontology development, automation,
extracting and mining valuable information in corporate environments. The aim
of this study is to provide a comprehensive and broad overview over the three
topics, give assistance for decision making in interesting scenarios and
choosing practical datasets for evaluating custom problem statements. Detailed
descriptions about attributes and metadata of the datasets should serve as
starting point for individual ideas and approaches
Mining Predictive Patterns and Extension to Multivariate Temporal Data
An important goal of knowledge discovery is the search for patterns in the data that can help explaining its underlying structure. To be practically useful, the discovered patterns should be novel (unexpected) and easy to understand by humans. In this thesis, we study the problem of mining patterns (defining subpopulations of data instances) that are important for predicting and explaining a specific outcome variable. An example is the task of identifying groups of patients that respond better to a certain treatment than the rest of the patients.
We propose and present efficient methods for mining predictive patterns for both atemporal and temporal (time series) data. Our first method relies on frequent pattern mining to explore the search space. It applies a novel evaluation technique for extracting a small set of frequent patterns that are highly predictive and have low redundancy. We show the benefits of this method on several synthetic and public datasets.
Our temporal pattern mining method works on complex multivariate temporal data, such as electronic health records, for the event detection task. It first converts time series into time-interval sequences of temporal abstractions and then mines temporal patterns backwards in time, starting from patterns related to the most recent observations. We show the benefits of our temporal pattern mining method on two real-world clinical tasks
Online Spectral Clustering on Network Streams
Graph is an extremely useful representation of a wide variety of practical systems in data analysis. Recently, with the fast accumulation of stream data from various type of networks, significant research interests have arisen on spectral clustering for network streams (or evolving networks). Compared with the general spectral clustering problem, the data analysis of this new type of problems may have additional requirements, such as short processing time, scalability in distributed computing environments, and temporal variation tracking. However, to design a spectral clustering method to satisfy these requirements certainly presents non-trivial efforts. There are three major challenges for the new algorithm design. The first challenge is online clustering computation. Most of the existing spectral methods on evolving networks are off-line methods, using standard eigensystem solvers such as the Lanczos method. It needs to recompute solutions from scratch at each time point. The second challenge is the parallelization of algorithms. To parallelize such algorithms is non-trivial since standard eigen solvers are iterative algorithms and the number of iterations can not be predetermined. The third challenge is the very limited existing work. In addition, there exists multiple limitations in the existing method, such as computational inefficiency on large similarity changes, the lack of sound theoretical basis, and the lack of effective way to handle accumulated approximate errors and large data variations over time. In this thesis, we proposed a new online spectral graph clustering approach with a family of three novel spectrum approximation algorithms. Our algorithms incrementally update the eigenpairs in an online manner to improve the computational performance. Our approaches outperformed the existing method in computational efficiency and scalability while retaining competitive or even better clustering accuracy. We derived our spectrum approximation techniques GEPT and EEPT through formal theoretical analysis. The well established matrix perturbation theory forms a solid theoretic foundation for our online clustering method. We facilitated our clustering method with a new metric to track accumulated approximation errors and measure the short-term temporal variation. The metric not only provides a balance between computational efficiency and clustering accuracy, but also offers a useful tool to adapt the online algorithm to the condition of unexpected drastic noise. In addition, we discussed our preliminary work on approximate graph mining with evolutionary process, non-stationary Bayesian Network structure learning from non-stationary time series data, and Bayesian Network structure learning with text priors imposed by non-parametric hierarchical topic modeling
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