Browsing by Author "Liao, Zhung-Xun"

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A Profile-based Framework for Interaction Prediction
(2012)
Liao, Zhung-Xun
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Peng, Wen-Chih
;
Yu, Philip S.
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資訊工程學系
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Department of Computer Science
In this paper, we generalize the link prediction problem to an interaction prediction problem. Compared with links in social networks, interactions can occur several times repeatedly. Based on the observation, we formulate an event-triggered interaction prediction problem. For example, we may want to know when a user connects to a website (e.g. Facebook), who will also connect to the website. We propose a Profile-based Interaction Prediction Framework (PIPF) which can solve the event-triggered interaction prediction problem efficiently and effectively. In PIPF, we first transform the interaction log into a Sliding-window Evolving Graph (SEG) to reduce the data volume and incrementally update SEG as interaction log grows. Then, we build profiles designed to present users' behavior by extracting the static and surprising features from SEG. The static (respectively, surprising) feature reflects the regularity of users' behavior (respectively, the temporal behavior). When an event occurs, we compute the similarity between the event and each candidate link. We propose two similarity functions for static and surprising features and an automatic selection strategy to control the influence of the two features. We use a real dataset that records Internet connections to evaluate the scalability, efficiency, and effectiveness of PIPF. The experimental results show that PIPF is far more scalable and efficient than the previous methods to perform real-time prediction.
AppNow: Predicting Usages of Mobile Applications on Smart Phones
(2012)
Liao, Zhung-Xun
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Lei, Po-Ruey
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Shen, Tsu-Jou
;
Li, Shou-Chung
;
Peng, Wen-Chih
Due to the proliferation of mobile applications (abbreviated as Apps) on smart phones, users can install many Apps to facilitate their life. Usually, users browse their Apps by swiping touch screen on smart phones, and are likely to spend much time on browsing Apps. In this paper, we design an AppNow widget that is able to predict users' Apps usage. Therefore, users could simply execute Apps from the widget. The main theme of this paper is to construct the temporal profiles which identify the relation between Apps and their usage times. In light of the temporal profiles of Apps, the AppNow widget predicts a list of Apps which are most likely to be used at the current time. In our experiments, we collected real usage traces to show that the accuracy of AppNow could reach 86% for identifying temporal profiles and 90% for predicting App usage.
Clustering spatial data with a geographic constraint: exploring local search
(2012-04-01)
Liao, Zhung-Xun
;
Peng, Wen-Chih
;
資訊工程學系
;
Department of Computer Science
Spatial data objects that possess attributes in the optimization domain and the geographic domain are now widely available. For example, sensor data are one kind of spatial data objects. The location of a sensor is an attribute in the geographic domain, while its reading is an attribute in the optimization domain. Previous studies discuss dual clustering problems that attempt to partition spatial data objects into several groups, such that objects in the same group have similar values in their optimization attributes and form a compact region in the geographic domain. However, previous studies do not clearly define compact regions. Therefore, this paper formulates a connective dual clustering problem with an explicit connected constraint given. Objects with a geographic distance smaller than or equal to the connected constraint are connected. The goal of the connective dual clustering problem is to derive clusters that contain objects with similar values in the optimization domain and are connected in the geographic domain. This study further proposes an algorithm CLS (Clustering with Local Search) to efficiently derive clusters. This algorithm consists of two phases: the ConGraph (standing for Connective Graph) transformation phase and the clustering phase. In the ConGraph transformation phase, CLS first transforms the data objects into a ConGraph that captures geographic constraints among data objects and selects initial seeds for clustering. Then, the initial seeds selected nearby data objects and formed coarse clusters by exploring local search in the clustering phase. Moreover, coarse clusters are merged and finely turned. Experiments show that CLS algorithm is more efficient and scalable than existing methods.
Mining sequential patterns across multiple sequence databases
(2009-10-01)
Peng, Wen-Chih
;
Liao, Zhung-Xun
;
資訊工程學系
;
Department of Computer Science
In this paper, given a set of sequence databases across multiple domains, we aim at mining multi-domain sequential patterns, where a multi-domain sequential pattern is a sequence of events whose occurrence time is within a pre-defined time window. We first: propose algorithm Naive in which multiple sequence databases are joined as one sequence database for utilizing traditional sequential pattern mining algorithms (e.g., PrefixSpan). Due to the nature of join operations, algorithm Naive is costly and is developed for comparison purposes. Thus, we propose two algorithms without any join operations for mining multidomain sequential patterns. Explicitly, algorithm IndividualMine derives sequential patterns in each domain and then iteratively combines sequential patterns among sequence databases of multiple domains to derive candidate multi-domain sequential patterns. However, not all sequential patterns mined in the sequence database of each domain are able to form multi-domain sequential patterns. To avoid the mining cost incurred in algorithm IndividualMine, algorithm PropagatedMine is developed. Algorithm PropagatedMine first performs one sequential pattern mining from one sequence database. In light of sequential patterns mined, algorithm PropagatedMine propagates sequential patterns mined to other sequence databases. Furthermore, sequential patterns mined are represented as a lattice structure for further reducing the number of sequential patterns to be propagated. In addition. we develop some mechanisms to allow some empty sets in multi-domain sequential patterns. Performance of the proposed algorithms is comparatively analyzed and sensitivity analysis is conducted. Experimental results show that by exploring propagation and lattice structures, algorithm PropagatedMine outperforms algorithm IndividualMine in terms of efficiency (i.e., the execution time). (C) 2009 Elsevier B.V. All rights reserved.
Mining Temporal Profiles of Mobile Applications for Usage Prediction
(2012)
Liao, Zhung-Xun
;
Lei, Po-Ruey
;
Shen, Tsu-Jou
;
Li, Shou-Chung
;
Peng, Wen-Chih
Due to the proliferation of mobile applications (abbreviated as Apps) on smart phones, users can install many Apps to facilitate their life. Usually, users browse their Apps by swiping touch screen on smart phones, and are likely to spend much time on browsing Apps. In this paper, we design an AppNow widget that is able to predict users' Apps usage. Therefore, users could simply execute Apps from the widget. The main theme of this paper is to construct the temporal profiles which identify the relation between Apps and their usage times. In light of the temporal profiles of Apps, the AppNow widget predicts a list of Apps which are most likely to be used at the current time. AppNow consists of three components, the usage logger, the temporal profile constructor and the Apps predictor. First, the usage logger records every App start time. Then, the temporal profiles are built by applying Discrete Fourier Transform and exploring usage periods and specific times. Finally, the system calculates the usage probability at current time for each App and shows a list of Apps with highest probability. In our experiments, we collected real usage traces to show that the accuracy of AppNow could reach 86% for identifying temporal profiles and 90% for predicting App usage.
On the Feature Discovery for App Usage Prediction in Smartphones
(2013)
Liao, Zhung-Xun
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Li, Shou-Chung
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Peng, Wen-Chih
;
Yu, Philip S.
;
Liu, Te-Chuan
With the increasing number of mobile Apps developed, they are now closely integrated into daily life. In this paper, we develop a framework to predict mobile Apps that are most likely to be used regarding the current device status of a smartphone. Such an Apps usage prediction framework is a crucial prerequisite for fast App launching, intelligent user experience, and power management of smartphones. By analyzing real App usage log data, we discover two kinds of features: The Explicit Feature (EF) from sensing readings of built-in sensors, and the Implicit Feature (IF) from App usage relations. The IF feature is derived by constructing the proposed App Usage Graph (abbreviated as AUG) that models App usage transitions. In light of AUG, we are able to discover usage relations among Apps. Since users may have different usage behaviors on their smartphones, we further propose one personalized feature selection algorithm. We explore minimum description length (MDL) from the training data and select those features which need less length to describe the training data. The personalized feature selection can successfully reduce the log size and the prediction time. Finally, we adopt the kNN classification model to predict Apps usage. Note that through the features selected by the proposed personalized feature selection algorithm, we only need to keep these features, which in turn reduces the prediction time and avoids the curse of dimensionality when using the kNN classifier. The results based on a real dataset demonstrate the effectiveness of the proposed framework and show the predictive capability for App usage prediction.