Efficient techniques for time-constrained information dissemination using location-based social networks Iouliana Litou n , Ioannis Boutsis, Vana Kalogeraki Athens University of Economics and Business, Patission 76, 10434 Athens, Greece article info Keywords: Distributed systems Social networks Information dissemination abstract Social networks have undergone an explosive growth in recent years. They constitute a central part of users' everyday lives as they are used as major tools for the spread of information, ideas and notifications among the members of the network. In this work we investigate the use of location-based social networks as a medium of emergency notifica- tion, for efficient dissemination of emergency information among members of the social network under time constraints. Our objective is the following: given a location-based social network comprising a number of mobile users, the social relationships among the users, the set of recipients, and the corresponding timeliness requirements, our goal is to select an appropriate subset of users so that the spread of information is maximized, time constraints are satisfied and costs are considered. We propose LATITuDE, our system that investigates the interactions among the members of the social network to infer their social relationships, and develop scalable dissemination mechanisms that select the most efficient set of users to initiate the dissemination process in order to maximize the information reach among the appropriate receivers within a time window. Our detailed experimental results illustrate that our approach is practical, effectively addresses the problem of informing the appropriate set of users within a deadline when an emergency event occurs, uses a small number of messages, and consistently outperforms its competitors. & 2016 Published by Elsevier Ltd. 1. Introduction Recently, we have observed the explosive growth of social networks such as Facebook [1], Twitter [2] and Google þ [3], that enumerate large amount of subscribers. For instance, Google þ has reached over 1.6 billion active users, while Facebook follows with over 1.2 billion users and Twitter with more than 600 million users. 1 These networks have been utilized as major tools for the spread of ideas, information and notifications among their members. Studies reveal that social networks can be exploited not only for “viral marketing” [4] (i.e., promote products to targeted sets of users that further propagate them through the word-of-mouth effect to reach a larger audience), but also for discovering emergent topics [5] and for emergency events alerting, management and public safety [6]. For example, people located in the vicinity of earthquakes share via Twitter, a well known social service for exchanging short text messages, anecdotal information related to the dissemination of seismically activity, that earthquake alerts lag behind firsthand notification [7,8]. Studies reveal that depending on the size and location of the earthquake, scientific alerts can take between 2 and 20 min to publish, while using Twitter's notification cap- abilities people were notified about the occurrence of the earthquakes shaking within seconds of their occurrence. Recently, Facebook, one of the most popular social net- works, announced the release of a tool, Safety Check, to be Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/infosys Information Systems http://dx.doi.org/10.1016/j.is.2015.12.002 0306-4379/& 2016 Published by Elsevier Ltd. n Corresponding author. E-mail address: litou@aueb.gr (I. Litou). 1 https://en.wikipedia.org/wiki/List_of_social_networking_websites Information Systems ∎ (∎∎∎∎) ∎∎∎–∎∎∎ Please cite this article as: I. Litou, et al., Efficient techniques for time-constrained information dissemination using location-based social networks, Information Systems (2016), http://dx.doi.org/10.1016/j.is.2015.12.002i