Overexposure-aware influence maximization

Viral marketing campaigns are often negatively affected by overexposure. Overexposure occurs when users become less likely to favor a promoted product, after receiving information about the product from too large a fraction of their friends. Yet, existing influence diffusion models do not take overexposure into account, effectively overestimating the number of users who favor the product and diffuse information about it. In this work, we propose the first influence diffusion model that captures overexposure. In our model, LAICO (Latency Aware Independent Cascade Model with Overexposure), the activation probability of a node representing a user is multiplied (discounted) by an overexposure score, which is calculated based on the ratio between the estimated and the maximum possible number of attempts performed to activate the node. We also study the influence maximization problem under LAICO. Since the spread function in LAICO is non-submodular, algorithms for submodular maximization are not appropriate to address the problem. Therefore, we develop an approximation algorithm which exploits monotone submodular upper and lower bound functions of spread, and a heuristic which aims to maximize a proxy function of spread iteratively. Our experiments show the effectiveness and efficiency of our algorithms

Reverse-Safe Data Structures for Text Indexing

We introduce the notion of reverse-safe data structures. These are data structures that prevent the reconstruction of the data they encode (i.e., they cannot be easily reversed). A data structure D is called z-reverse-safe when there exist at least z datasets with the same set of answers as the ones stored by D. The main challenge is to ensure that D stores as many answers to useful queries as possible, is constructed efficiently, and has size close to the size of the original dataset it encodes. Given a text of length n and an integer z, we propose an algorithm which constructs a z-reverse-safe data structure that has size O(n) and answers pattern matching queries of length at most d optimally, where d is maximal for any such z-reverse-safe data structure. The construction algorithm takes O(n ω log d) time, where ω is the matrix multiplication exponent. We show that, despite the n ω factor, our engineered implementation takes only a few minutes to finish for million-letter texts. We further show that plugging our method in data analysis applications gives insignificant or no data utility loss. Finally, we show how our technique can be extended to support applications under a realistic adversary model

Examining the influences of service quality and corporate image on students' loyalty of boarding schools in the UK: A study of Chinese students

The purpose of this study is to explore the impact of service quality and corporate image on students’ loyalty of boarding schools in the UK. Valid responses obtained from Chinese students in British boarding schools (n =300) were analysed using structural equation modelling. The results of the empirical research on Chinese students reveal how students’ loyalty relies on the level of service quality and corporate image. Additionally, corporate image mediates the relationship between service quality and students’ loyalty. Different from previous studies that investigated service quality in the higher education sector, this study extends the extant literature by examining the importance of corporate image on boarding schools. The results also corroborate the applicability of the five dimensions of SERVQUAL model to the boarding school sector

Assessing the drivers of online impulse buying

Given the rapidly growing popularity of online impulse buying using digital and social media platforms, it has raised important interests about the antecedents of such consumer behaviour. Data analysis was conducted using confirmatory factor analysis and structural equation modelling. The results from a survey of 310 online buyers suggest that trust holds the strongest correlation with the experiential value. This study provides new insights for marketing literature and online retailers

Text Indexing for Long Patterns: Anchors are All you Need

PVLDB Artifact Availability: The source code, data, and/or other artifacts have been made available at https://github.com/lorrainea/BDA- index.Copyright © 2023 the owner/author(s). In many real-world database systems, a large fraction of the data is represented by strings: sequences of letters over some alphabet. This is because strings can easily encode data arising from different sources. It is often crucial to represent such string datasets in a compact form but also to simultaneously enable fast pattern matching queries. This is the classic text indexing problem. The four absolute measures anyone should pay attention to when designing or implementing a text index are: (i) index space; (ii) query time; (iii) construction space; and (iv) construction time. Unfortunately, however, most (if not all) widely-used indexes (e.g., suffix tree, suffix array, or their compressed counterparts) are not optimized for all four measures simultaneously, as it is difficult to have the best of all four worlds. Here, we take an important step in this direction by showing that text indexing with locally consistent anchors (lc-anchors) offers remarkably good performance in all four measures, when we have at hand a lower bound l on the length of the queried patterns --- which is arguably a quite reasonable assumption in practical applications. Specifically, we improve on the construction of the index proposed by Loukides and Pissis, which is based on bidirectional string anchors (bd-anchors), a new type of lc-anchors, by: (i) designing an average-case linear-time algorithm to compute bd-anchors; and (ii) developing a semi-external-memory implementation to construct the index in small space using near-optimal work. We then present an extensive experimental evaluation, based on the four measures, using real benchmark datasets. The results show that, for long patterns, the index constructed using our improved algorithms compares favorably to all classic indexes: (compressed) suffix tree; (compressed) suffix array; and the FM-index.European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreements No 872539 and 956229, respectively; and by UKRI through REPHRAIN (EP/V011189/1)

Bash Cookbook

The key to mastering any Unix system, especially Linux and Mac OS X, is a thorough knowledge of shell scripting. Scripting is a way to harness and customize the power of any Unix system, and it's an essential skill for any Unix users, including system administrators and professional OS X developers. But beneath this simple promise lies a treacherous ocean of variations in Unix commands and standards.bash Cookbook teaches shell scripting the way Unix masters practice the craft. It presents a variety of recipes and tricks for all levels of shell programmers so that anyone can become a proficien