All three-manifolds are known to occur as Cauchy surfaces of asymptotically flat vacuum spacetimes and of spacetimes with positive-energy sources. We prove here the conjecture that general relativity does not allow an observer to probe the topology of spacetime: any topological structure collapses too quickly to allow light to traverse it. More precisely, in a globally hyperbolic, asymptoticall...

Social media companies operating in China face a complex array of regulations and are liable for content posted to their platforms. Through reverse engineering we provide a view into how keyword censorship operates on four popular social video platforms in China: YY, 9158, Sina Show, and GuaGua. We also find keyword surveillance capabilities on YY. Our findings show inconsistencies in the imple...

One particular area of contention in discussions of Freudian dream theory and its relation to the neuroscientific evidence is the notion of “disguise-censorship” and its relation to dream bizarreness. The discussion to date, however, has neglected the conceptual basis of repression and disguise-censorship, and this paper aims to clarify the role of repression in dreaming and its contribution to...

Roya Ensafi is a Research Assistant Professor in Computer Science and Engineering at the University of Michigan, where her research focuses on computer networking and security. She pioneered the use of side-channels to remotely measure network interference and censorship of Internet traffic. Prior to joining Michigan, she was a postdoc at Princeton University. [email protected] Despite the perva...

For—according to the lore—any attempt at pullingoff this featwill reduce themtomaterial implicationand that is decidedlynot agoodwayof assigning truth-conditions to ordinary indicative if s. That is too bad since it seems like they are bounded from above by strict implication (they are true when their antecedents straight out imply their consequents), are bounded from below by material implicat...

Motivated by recent interest in black holes whose asymptotic geometry approaches that of anti-de Sitter spacetime, we give a proof of topological censorship applicable to spacetimes with such asymptotic behavior. Employing a useful rephrasing of topological censorship as a property of homotopies of arbitrary loops, we then explore the consequences of topological censorship for horizon topology ...

We propose Lavinia, a censorship resistant publishing system that incentivizes document storage through the use of an anonymous, distributed, time-locked payment system. This has the advantage of allowing the publisher to decide whether a document is worth storing, and for how long, instead of relying on public interest or an appointed editorial board. We give a description of related work in c...

In this paper we propose a new Peer-to-Peer architecture for a censorship resistant system with user, server and active-server document anonymity as well as efficient document retrieval. The retrieval service is layered on top of an existing Peer-to-Peer infrastructure, which should facilitate its implementation. The key idea is to separate the role of document storers from the machines visible...

Recent developments in entertainment and communications technology have created challenges for those who make classification decisions and who enforce censorship law. High speed private internet access, DVD technology, mobile telephony and advances in video gaming have all created challenges for censorship legislation originally designed to deal with films, videos and paper publications. The la...

Censorship of the Internet is widespread around the world. As access to the web becomes increasingly ubiquitous, filtering of this resource becomes more pervasive. Transparency about specific content that citizens are denied access to is atypical. To counter this, numerous techniques for maintaining URL filter lists have been proposed by various individuals and organisations that aim to empiric...