Role Mining in the Presence of Noise

Abstract. The problem of role mining, a bottom-up process of discovering roles from the user-permission assignments (UPA), has drawn increasing attention in recent years. The role mining problem (RMP) and several of its variants have been proposed in the literature. While the basic RMP discovers roles that exactly represent the UPA, the inexact variants, such as the δ-approx RMP and MinNoise-RMP, allow for some inexactness in the sense that the discovered roles do not have to exactly cover the entire UPA. However, since data in real life is never completely clean, the role mining process is only effective if it is robust to noise. This paper takes the first step towards addressing this issue. Our goal in this paper is to examine if the effect of noise in the UPA could be ameliorated due to the inexactness in the role mining process, thus having little negative impact on the discovered roles. Specifically, we define a formal model of noise and experimentally evaluate the previously proposed algorithm for δ-approx RMP against its robustness to noise. Essentially, this would allow one to come up with strategies to minimize the effect of noise while discovering roles. Our experiments on real data indicate that the role mining process can preferentially cover a lot of the real assignments and leave potentially noisy assignments for further examination. We explore the ramifications of noisy data and discuss next steps towards coming up with more effective algorithms for handling such data

MOSDEN: A Scalable Mobile Collaborative Platform for Opportunistic Sensing Applications

Mobile smartphones along with embedded sensors have become an efficient enabler for various mobile applications including opportunistic sensing. The hi-tech advances in smartphones are opening up a world of possibilities. This paper proposes a mobile collaborative platform called MOSDEN that enables and supports opportunistic sensing at run time. MOSDEN captures and shares sensor data across multiple apps, smartphones and users. MOSDEN supports the emerging trend of separating sensors from application-specific processing, storing and sharing. MOSDEN promotes reuse and re-purposing of sensor data hence reducing the efforts in developing novel opportunistic sensing applications. MOSDEN has been implemented on Android-based smartphones and tablets. Experimental evaluations validate the scalability and energy efficiency of MOSDEN and its suitability towards real world applications. The results of evaluation and lessons learned are presented and discussed in this paper.Comment: Accepted to be published in Transactions on Collaborative Computing, 2014. arXiv admin note: substantial text overlap with arXiv:1310.405

The Role of Text Pre-processing in Sentiment Analysis

It is challenging to understand the latest trends and summarise the state or general opinions about products due to the big diversity and size of social media data, and this creates the need of automated and real time opinion extraction and mining. Mining online opinion is a form of sentiment analysis that is treated as a difficult text classification task. In this paper, we explore the role of text pre-processing in sentiment analysis, and report on experimental results that demonstrate that with appropriate feature selection and representation, sentiment analysis accuracies using support vector machines (SVM) in this area may be significantly improved. The level of accuracy achieved is shown to be comparable to the ones achieved in topic categorisation although sentiment analysis is considered to be a much harder problem in the literature