We present PoWerStore, the first efficient robust storage protocol that achieves optimal latency without using digital signatures. PoWerStore's robustness comprises tolerating asynchrony, maximum number of Byzantine storage servers, any number of Byzantine readers and crash-faulty writers, and guaranteeing wait-freedom and linearizability of read write operations. PoWerStore's efficiency stems from combining lightweight authentication, erasure coding and metadata write-backs where readers write-back only metadata to achieve linearizability. At the heart of PoWerStore are Proofs of Writing (PoW): a novel storage technique based on lightweight cryptography. PoW enable reads and writes in the single-writer variant of PoWerStore to have latency of 2 rounds of communication between a client and storage servers in the worst-case (which we show optimal). We further present and implement a multi-writer PoWerStore variant featuring 3-round writes reads where the third read round is invoked only under active attacks, and show that it outperforms existing robust storage protocols, including crash-tolerant ones.
A seminal crash-tolerant read write storage implementation assuming a majority of correct processes was presented in @cite_13 . In the original single-writer variant of @cite_13 , read operations always take 2 rounds between a client and servers with write-backs in the second round. On the other hand all write operations complete in a single round; in the multi-writer variant @cite_5 , the second write round is necessary. Server state modifications by readers introduced by @cite_13 are unavoidable; namely, @cite_23 showed a @math lower bound on the number of servers that a reader has to modify in any wait-free linearizable storage. However, robust storage implementations differ in the strategy employed by readers: in some protocols readers write-back data (e.g., @cite_13 @cite_47 @cite_42 @cite_37 @cite_49 @cite_33 ) whereas in others readers only write metadata to servers (e.g., @cite_23 @cite_18 @cite_41 ).
@cite_37 @cite_18 @cite_33 @cite_41 @cite_42 @cite_23 @cite_49 @cite_5 @cite_47 @cite_13
1967118107 2086186470 2089883915 1503117778 2165838660 1587246893 1835459221 2065180040
We study the time-complexity of robust atomic read write storage from fault-prone storage components in asynchronous message-passing systems. Robustness here means wait-free tolerating the largest possible number t of Byzantine storage component failures (optimal resilience) without relying on data authentication. We show that no single-writer multiple-reader (SWMR) robust atomic storage implementation exists if (a) read operations complete in less than four communication round-trips (rounds), and (b) the time complexity of write operations is constant. More precisely, we present two lower bounds. The first is a read lower bound stating that three rounds of communication are necessary to read from a SWMR robust atomic storage. The second is a write lower bound, showing that Ω(log(t)) write rounds are necessary to read in three rounds from such a storage. Applied to known results, our lower bounds close a fundamental gap: we show that time-optimal robust atomic storage can be obtained using well-known transformations from regular to atomic storage and existing time-optimal regular storage implementations. A citing sentence is one that appears in a scientific article and cites previous work. Citing sentences have been studied and used in many applications. For example, they have been used in scientific paper summarization, automatic survey generation, paraphrase identification, and citation function classification. Citing sentences that cite multiple papers are common in scientific writing. This observation should be taken into consideration when using citing sentences in applications. For instance, when a citing sentence is used in a summary of a scientific paper, only the fragments of the sentence that are relevant to the summarized paper should be included in the summary. In this paper, we present and compare three different approaches for identifying the fragments of a citing sentence that are related to a given target reference. Our methods are: word classification, sequence labeling, and segment classification. Our experiments show that segment classification achieves the best results. This paper establishes tight bounds on the best-case time-complexity of distributed atomic read write storage implementations that tolerate worst-case conditions. We study asynchronous robust implementations where a writer and a set of reader processes (clients) access an atomic storage implemented over a set of 2t+b+1 server processes of which t can fail: b of these can be malicious and the rest can crash. We define a lucky operation (read or write) as one that runs synchronously and without contention. It is often argued in practice that lucky operations are the most frequent. We determine the exact conditions under which a lucky operation can be fast, namely expedited in onecommunication round-trip with no data authentication. We show that every lucky write (resp., read) can be fast despite fw(resp., fr) actual failures, if and only if fw + fr t-b. This paper investigates time-efficient implementations of atomic read-write registers in message-passing systems where the number of readers can be unbounded. In particular we study the case of a single writer, multiple readers, and S servers, such that the writer, any subset of the readers, and up to t servers may crash. A recent result of [P. Dutta, R. Guerraoui, R.R. Levy, A. Chakraborty, How fast can a distributed atomic read be? In: Proceedings of the 23rd ACM Symposium on Principles of Distributed Computing, 2004, pp. 236-245] shows how to obtain fast implementations in which both reads and writes complete in one communication round-trip, under the constraint that the number of readers is less than St-2, where t We study efficient and robust implementations of an atomic read-write data structure over an asynchronous distributed message-passing system made of reader and writer processes, as well as a number of servers implementing the data structure. We determine the exact conditions under which every read and write involves one round of communication with the servers. These conditions relate the number of readers to the tolerated number of faulty servers and the nature of these failures. This paper describes a decentralized consistency protocol for survivable storage that exploits local data versioning within each storage-node. Such versioning enables the protocol to efficiently provide linearizability and wait-freedom of read and write operations to erasure-coded data in asynchronous environments with Byzantine failures of clients and servers. By exploiting versioning storage-nodes, the protocol shifts most work to clients and allows highly optimistic operation: reads occur in a single round-trip unless clients observe concurrency or write failures. Measurements of a storage system prototype using this protocol show that it scales well with the number of failures tolerated, and its performance compares favorably with an efficient implementation of Byzantine-tolerant state machine replication. When data is stored on a faulty server that is accessed concurrently by multiple clients, the server may present inconsistent data to different clients. For example, the server might complete a write operation of one client, but respond with stale data to another client. Mazieres and Shasha (PODC 2002) introduced the notion of fork-consistency, also called fork-linearizability, which ensures that the operations seen by every client are linearizable and guarantees that if the server causes the views of two clients to differ in a single operation, they may never again see each other's updates after that without the server being exposed as faulty. In this paper, we improve the communication complexity of their fork-linearizable storage access protocol with n clients from Ω(n2) to O(n). We also prove that in every such protocol, a reader must wait for a concurrent writer. This explains a seeming limitation of their and of our improved protocol. Furthermore, we give novel characterizations of fork-linearizability and prove that it is neither stronger nor weaker than sequential consistency. Abstract Documents in computer-readable form can be used to provide information about other documents, i.e. those they cite. To do this efficiently requires procedures for computer recognition of citing statements. This is not easy, especially for multi-sentence citing statements. Computer recognition procedures have been developed which are accurate to the following extent: 73 of the words in statements selected by computer procedures as being citing statements are words which are correctly attributable to the corresponding documents. The retrieval effectiveness of computer-recognized citing statements was tested in the following way. First, for eight retrieval requests in inorganiic chemistry, average recall by search of Chemical Abstracts Service indexing and Chemical Abstracts abstract text words was found to be 50 . Words from citing statements referring to the papers to be retrieved were then added to the index terms and abstract words as additional access points, and searching was repeated. Average recall increased to 70 . Only words from citing statements published within a year of the cited papers were used. The retrieval effect of citing statement words alone (published within a year) without index or abstract terms was the following: average recall was 40 . When just the words of the titles of the cited papers were added to those citing statement words, average recall increased to 50 . In a document network such as a citation network of scientific documents, web-logs, etc., the content produced by authors exhibits their interest in certain topics. In addition some authors influence other authors' interests. In this work, we propose to model the influence of cited authors along with the interests of citing authors. Moreover, we hypothesize that apart from the citations present in documents, the context surrounding the citation mention provides extra topical information about the cited authors. However, associating terms in the context to the cited authors remains an open problem. We propose novel document generation schemes that incorporate the context while simultaneously modeling the interests of citing authors and influence of the cited authors. Our experiments show significant improvements over baseline models for various evaluation criteria such as link prediction between document and cited author, and quantitatively explaining unseen text. Purpose – The purpose of this paper is to suggest an alternative to the widely used Times Cited criterion for analysing citation networks. The approach involves taking account of the natures of the papers that cite a given paper, so as to differentiate between papers that attract the same number of citations.Design methodology approach – ArticleRank is an algorithm that has been derived from Google's PageRank algorithm to measure the influence of journal articles. ArticleRank is applied to two datasets – a citation network based on an early paper on webometrics, and a self‐citation network based on the 19 most cited papers in the Journal of Documentation – using citation data taken from the Web of Knowledge database.Findings – ArticleRank values provide a different ranking of a set of papers from that provided by the corresponding Times Cited values, and overcomes the inability of the latter to differentiate between papers with the same numbers of citations. The difference in rankings between Times Cited ... Scholars are increasingly citing electronic “web references” which are not preserved in libraries or full text archives. WebCite is a new standard for citing web references. To “webcite” a document involves archiving the cited Web page through www.webcitation.org and citing the WebCite permalink instead of (or in addition to) the unstable live Web page. This journal has amended its “instructions for authors” accordingly, asking authors to archive cited Web pages before submitting a manuscript. Almost 200 other journals are already using the system. We discuss the rationale for WebCite, its technology, and how scholars, editors, and publishers can benefit from the service. Citing scholars initiate an archiving process of all cited Web references, ideally before they submit a manuscript. Authors of online documents and websites which are expected to be cited by others can ensure that their work is permanently available by creating an archived copy using WebCite and providing the citation information including the WebCite link on their Web document(s). Editors should ask their authors to cache all cited Web addresses (Uniform Resource Locators, or URLs) “prospectively” before submitting their manuscripts to their journal. Editors and publishers should also instruct their copyeditors to cache cited Web material if the author has not done so already. Finally, WebCite can process publisher submitted “citing articles” (submitted for example as eXtensible Markup Language [XML] documents) to automatically archive all cited Web pages shortly before or on publication. Finally, WebCite can act as a focussed crawler, caching retrospectively references of already published articles. Copyright issues are addressed by honouring respective Internet standards (robot exclusion files, no-cache and no-archive tags). Long-term preservation is ensured by agreements with libraries and digital preservation organizations. The resulting WebCite Index may also have applications for research assessment exercises, being able to measure the impact of Web services and published Web documents through access and Web citation metrics. @PARASPLIT [J Med Internet Res 2005;7(5):e60] Historically, papers have been physically bound to the journal in which they were published; but in the digital age papers are available individually, no longer tied to their respective journals. Hence, papers now can be read and cited based on their own merits, independently of the journal's physical availability, reputation, or impact factor (IF). We compare the strength of the relationship between journals' IFs and the actual citations received by their respective papers from 1902 to 2009. Throughout most of the 20th century, papers' citation rates were increasingly linked to their respective journals' IFs. However, since 1990, the advent of the digital age, the relation between IFs and paper citations has been weakening. This began first in physics, a field that was quick to make the transition into the electronic domain. Furthermore, since 1990 the overall proportion of highly cited papers coming from highly cited journals has been decreasing and, of these highly cited papers, the proportion not coming from highly cited journals has been increasing. Should this pattern continue, it might bring an end to the use of the IF as a way to evaluate the quality of journals, papers, and researchers. © 2012 Wiley Periodicals, Inc. This paper studies the time complexity of reading unauthenticated data from a distributed storage made of a set of failure-prone base objects. More specifically, we consider the abstraction of a robust read write storage that provides wait-free access to unauthenticated data over a set of base storage objects with t possible failures, out of which at most b are arbitrary and the rest are simple crash failures.We prove a 2 communication round-trip lower bound for reading from a safe storage that uses at most 2t+2b base objects, independently of the number or round-trips needed by the writer. We then prove the lower bound tight by exhibiting a regular storage that uses 2t+b+1 base objects (optimal resilience) and features 2 communication round-trips for both read and write operations. A new form of document coupling called co-citation is defined as the frequency with which two documents are cited together. The co-citation frequency of two scientific papers can be determined by comparing lists of citing documents in the Science Citation Index and counting identical entries. Networks of co-cited papers can be generated for specific scientific specialties, and an example is drawn from the literature of particle physics. Co-citation patterns are found to differ significantly from bibliographic coupling patterns, but to agree generally with patterns of direct citation. Clusters of co-cited papers provide a new way to study the specialty structure of science. They may provide a new approach to indexing and to the creation of SDI profiles. Citation relationship between scientific publications has been successfully used for scholarly bibliometrics, information retrieval and data mining tasks, and citation-based recommendation algorithms are well documented. While previous studies investigated citation relations from various viewpoints, most of them share the same assumption that, if paper1 cites paper2 (or author1 cites author2), they are connected, regardless of citation importance, sentiment, reason, topic, or motivation. However, this assumption is oversimplified. In this study, we employ an innovative "context-rich heterogeneous network" approach, which paves a new way for citation recommendation task. In the network, we characterize 1) the importance of citation relationships between citing and cited papers, and 2) the topical citation motivation. Unlike earlier studies, the citation information, in this paper, is characterized by citation textual contexts extracted from the full-text citing paper. We also propose algorithm to cope with the situation when large portion of full-text missing information exists in the bibliographic repository. Evaluation results show that, context-rich heterogeneous network can significantly enhance the citation recommendation performance. An overwhelming number of news articles are available every day via the internet. Unfortunately, it is impossible for us to peruse more than a handful; furthermore it is difficult to ascertain an article’s social context, i.e., is it popular, what sorts of people are reading it, etc. In this paper, we develop a system to address this problem in the restricted domain of political news by harnessing implicit and explicit contextual information from the blogosphere. Specifically, we track thousands of blogs and the news articles they cite, collapsing news articles that have highly overlapping content. We then tag each article with the number of blogs citing it, the political orientation of those blogs, and the level of emotional charge expressed in the blog posts that link to the news article. We summarize and present the results to the user via a novel visualization which displays this contextual information; the user can then find the most popular articles, the articles most cited by liberals, the articles most emotionally discussed in the political blogosphere, etc. In recent years scholars have built maps of science by connecting the academic fields that cite each other, are cited together, or that cite a similar literature. But since scholars cannot always publish in the fields they cite, or that cite them, these science maps are only rough proxies for the potential of a scholar, organization, or country, to enter a new academic field. Here we use a large dataset of scholarly publications disambiguated at the individual level to create a map of science-or research space-where links connect pairs of fields based on the probability that an individual has published in both of them. We find that the research space is a significantly more accurate predictor of the fields that individuals and organizations will enter in the future than citation based science maps. At the country level, however, the research space and citations based science maps are equally accurate. These findings show that data on career trajectories-the set of fields that individuals have previously published in-provide more accurate predictors of future research output for more focalized units-such as individuals or organizations-than citation based science maps. When we write or prepare to write a research paper, we always have appropriate references in mind. However, there are most likely references we have missed and should have been read and cited. As such a good citation recommendation system would not only improve our paper but, overall, the efficiency and quality of literature search. Usually, a citation's context contains explicit words explaining the citation. Using this, we propose a method that "translates" research papers into references. By considering the citations and their contexts from existing papers as parallel data written in two different "languages", we adopt the translation model to create a relationship between these two "vocabularies". Experiments on both CiteSeer and CiteULike dataset show that our approach outperforms other baseline methods and increase the precision, recall and f-measure by at least 5 to 10 , respectively. In addition, our approach runs much faster in the both training and recommending stage, which proves the effectiveness and the scalability of our work. This paper introduces a general formulation of atomic snapshot memory , a sharedmemory partitioned into words written( updated ) by individual processes, orinstantaneously read ( scanned ) in itsentirety. This paper presents three wait-free implementations of atomicsnapshot memory. The first implementation in this paper uses unbounded(integer) fields in these registers, and is particularly easy tounderstand. The second implementation uses bounded registers. Itscorrectness proof follows the ideas of the unbounded implementation.Both constructions implement a single-writer snapshot memory, in whicheach word may be updated by only one process, from single-writer, n -reader registers. The thirdalgorithm implements a multi-writer snapshot memory from atomic n -writer, n -reader registers, again echoing keyideas from the earlier constructions. All operations requireT( n 2 ) readsand writes to the component shared registers in the worst case. — Authors' Abstract Reading academic paper is a daily task for researchers and graduate students. However, reading effectively can be challenging, particularly for novices in scientific research. For example, when readers are reading the related work section that cites a fair number of references in limited page space, they often need to flip back and forth between the text and the references and may also frequently search elsewhere for more information about the references. This increases the difficulty of understanding a paper. In this paper, we propose a narrative visualization system that helps the reading of academic papers. As a first step, we adopt narrative visualization to present literature review as interactive slides. Specifically, we propose a narrative structure with three levels of granularities that the reader can drill down or roll up freely. The logic flow of a slideshow can be organized based on the paper's presentation or citations. We demonstrate the effectiveness of our system through several case studies and user studies. The results show that the system allows users to quickly track and glance related work, making paper reading more effective and enjoyable.