text: Social media is an area where users often experience censorship through a variety of means such as the restriction of search terms or active and retroactive deletion of messages. In this paper we examine the feasibility of automatically detecting censorship of microblogs. We use a network growing model to simulate discussion over a microblog follow network and compare two censorship strategies to simulate varying levels of message deletion. Using topological features extracted from the resulting graphs, a classifier is trained to detect whether or not a given communication graph has been censored. The results show that censorship detection is feasible under empirically measured levels of message deletion. The proposed framework can enable automated censorship measurement and tracking, which, when combined with aggregated citizen reports of censorship, can allow users to make informed decisions about online communication habits.
  @cite_21: We study the tolerance of random networks to intentional attack, whereby a fraction @math of the most connected sites is removed. We focus on scale-free networks, having connectivity distribution @math , and use percolation theory to study analytically and numerically the critical fraction @math needed for the disintegration of the network, as well as the size of the largest connected cluster. We find that even networks with @math , known to be resilient to random removal of sites, are sensitive to intentional attack. We also argue that, near criticality, the average distance between sites in the spanning (largest) cluster scales with its mass, @math , as @math , rather than as @math , as expected for random networks away from criticality.
  @cite_17: With Twitter and Facebook blocked in China, the stream of information from Chinese domestic social media provides a case study of social media behavior under the influence of active censorship. While much work has looked at efforts to prevent access to information in China (including IP blocking of foreign Web sites or search engine filtering), we present here the first large–scale analysis of political content censorship in social media, i.e. , the active deletion of messages published by individuals. In a statistical analysis of 56 million messages (212,583 of which have been deleted out of 1.3 million checked, more than 16 percent) from the domestic Chinese microblog site Sina Weibo, and 11 million Chinese–language messages from Twitter, we uncover a set a politically sensitive terms whose presence in a message leads to anomalously higher rates of deletion. We also note that the rate of message deletion is not uniform throughout the country, with messages originating in the outlying provinces of Tibet and Qinghai exhibiting much higher deletion rates than those from eastern areas like Beijing.
  @cite_6: We present measurements and analysis of censorship on Weibo, a popular microblogging site in China. Since we were limited in the rate at which we could download posts, we identified users likely to participate in sensitive topics and recursively followed their social contacts. We also leveraged new natural language processing techniques to pick out trending topics despite the use of neologisms, named entities, and informal language usage in Chinese social media. We found that Weibo dynamically adapts to the changing interests of its users through multiple layers of filtering. The filtering includes both retroactively searching posts by keyword or repost links to delete them, and rejecting posts as they are posted. The trend of sensitive topics is short-lived, suggesting that the censorship is effective in stopping the "viral" spread of sensitive issues. We also give evidence that sensitive topics in Weibo only scarcely propagate beyond a core of sensitive posters.
  @cite_12: We study the tolerance of a scale-free network (having a connectivity distribution P(k)∼k−γ) under systematic variation of the attack strategy. In an attack, the probability that a given node is destroyed, depends on the number of its links k via W(k)∼kα, where α varies from −∞ (most harmless attack) to +∞ (most harmful “intentional” attack). We show that the critical fraction pc needed to disintegrate the network increases monotonically when α is decreased and study how at pc the topology of the diluted network depends on the attack strategy.
  @cite_11: Recent advances in network theory have led to considerable progress in our understanding of complex real world systems and their behavior in response to external threats or fluctuations. Much of this research has been invigorated by demonstration of the ‘robust, yet fragile’ nature of cellular and large-scale systems transcending biology, sociology, and ecology, through application of the network theory to diverse interactions observed in nature such as plant-pollinator, seed-dispersal agent and host-parasite relationships. In this work, we report the development of NEXCADE, an automated and interactive program for inducing disturbances into complex systems defined by networks, focusing on the changes in global network topology and connectivity as a function of the perturbation. NEXCADE uses a graph theoretical approach to simulate perturbations in a user-defined manner, singly, in clusters, or sequentially. To demonstrate the promise it holds for broader adoption by the research community, we provide pre-simulated examples from diverse real-world networks including eukaryotic protein-protein interaction networks, fungal biochemical networks, a variety of ecological food webs in nature as well as social networks. NEXCADE not only enables network visualization at every step of the targeted attacks, but also allows risk assessment, i.e. identification of nodes critical for the robustness of the system of interest, in order to devise and implement context-based strategies for restructuring a network, or to achieve resilience against link or node failures. Source code and license for the software, designed to work on a Linux-based operating system (OS) can be downloaded at http: www.nipgr.res.in nexcade_download.html. In addition, we have developed NEXCADE as an OS-independent online web server freely available to the scientific community without any login requirement at http: www.nipgr.res.in nexcade.html.
summary: @cite_17 uncovered politically sensitive terms more likely to be actively and retroactively deleted in a comparison between censorship on Twitter and China's Sina Weibo microblogging services. A random sample of collected messages found that 16.25 Initial research by @cite_6 shows that active and retroactive censorship to a large extent succeeds in stemming the spread of information on microblogs. In a subsequent work, the authors studied the time distribution of deleted messages and found that nearly 30 Network perturbation and resilience is a closely related field where network metrics are studied under destructive processes that iteratively remove nodes or edges @cite_21 @cite_12 @cite_11 , however, these works do not consider censoring models for these processes nor do they formulate the problem as one of classification.