Harvard University

Displaying 1-40 of 183 results

  • White Papers // Jul 2013

    A Uniform Min-Max Theorem with Applications in Cryptography

    The authors present a new, more constructive proof of von neumann's min-max theorem for two-player zero-sum game - specifically, an algorithm that builds a near-optimal mixed strategy for the second player from several best-responses of the second player to mixed strategies of the first player. The algorithm extends previous paper...

    Provided By Harvard University

  • White Papers // Mar 2013

    A Highly Scalable Key Pre-Distribution Scheme for Wireless Sensor Networks

    Given the sensitivity of the potential WSN applications and because of resource limitations, key management emerges as a challenging issue for WSNs. One of the main concerns when designing a key management scheme is the network scalability. Indeed, the protocol should support a large number of nodes to enable a...

    Provided By Harvard University

  • White Papers // Jan 2013

    Scaling Network-Based Spectrum Analyzer With Constant Communication Cost

    The authors propose a spectrum analyzer that leverages many networked commodity sensor nodes, each of which samples its portion in a wideband spectrum. The sensors operate in parallel and transmit their measurements over a wireless network without performing any significant computations such as FFT. The measurements are forwarded to the...

    Provided By Harvard University

  • White Papers // Oct 2012

    Loopy Belief Propagation as a Basis for Communication in Sensor Networks

    Sensor networks are an exCltmg new kmd of computer system. Consisting of a large number of tiny, cheap computational devices physically distributed in an environment, they gather and process data about the environment in real time. One of the central questions in sensor networks is what to do with the...

    Provided By Harvard University

  • White Papers // Sep 2012

    Compressed Statistical Testing and Application to Radar

    The authors present Compressed Statistical Testing (CST) with an illustrative application to radar target detection. They characterize an optimality condition for a compressed domain test to yield the same result as the corresponding test in the uncompressed domain. They demonstrate by simulation that under high SNR, a likelihood ratio test...

    Provided By Harvard University

  • White Papers // Aug 2012

    Output Compression for IC Fault Detection Using Compressive Sensing

    The process of detecting logical faults in Integrated Circuits (ICs) due to manufacturing variations is bottlenecked by the I/O cost of scanning in test vectors and offloading test results. Traditionally, the output bottleneck is alleviated by reducing the number of bits in output responses using XOR networks, or computing signatures...

    Provided By Harvard University

  • White Papers // Aug 2012

    Determining RF Angle of Arrival Using COTS Antenna Arrays: A Field Evaluation

    The authors are interested in estimating the angle of arrival of an RF signal by using Commercial-Off-The-Shelf (COTS) Software-Defined Radios (SDRs). The proposed COTS-based approach has the advantages of flexibility, low cost and ease of deployment, but - unlike traditional phased antenna arrays in which elements are already phase-aligned -...

    Provided By Harvard University

  • White Papers // Aug 2012

    Compressive Sensing With Optimal Sparsifying Basis and Applications in Spectrum Sensing

    The authors describe a method of integrating Karhunen-Loeve Transform (KLT) into compressive sensing, which can as a result improve the compression ratio without affecting the accuracy of decoding. They present two complementary results: by using KLT to find an optimal basis for decoding they can drastically reduce the number of...

    Provided By Harvard University

  • White Papers // Aug 2012

    Compressive Sensing Medium Access Control for Wireless LANs

    The authors propose a Medium Access Control (MAC) protocol for wireless Local Area Networks (LANs) that leverages the theory of compressive sensing. The proposed Compressive Sensing MAC (CS-MAC) exploits the sparse property that, at a given time, only a few hosts are expected to request for radio channel access. Under...

    Provided By Harvard University

  • White Papers // Jul 2012

    A Chip Architecture for Compressive Sensing Based Detection of Ic Trojans

    The authors present a chip architecture for a compressive sensing based method that can be used in conjunction with the JTAG standard to detect IC Trojans. The proposed architecture compresses chip output resulting from a large number of test vectors applied to a Circuit Under Test (CUT). They describe their...

    Provided By Harvard University

  • White Papers // Jun 2012

    Designing Informative Securities

    The authors create a formal framework for the design of informative securities in prediction markets. These securities allow a market organizer to infer the likelihood of events of interest as well as if he knew all of the traders' private signals. They consider the design of markets that are always...

    Provided By Harvard University

  • White Papers // May 2012

    Verifiable Computation With Massively Parallel Interactive Proofs

    As the cloud computing paradigm has gained prominence, the need for verifiable computation has grown increasingly urgent. Protocols for verifiable computation enable a weak client to outsource difficult computations to a powerful, but untrusted server, in a way that provides the client with a guarantee that the server performed the...

    Provided By Harvard University

  • White Papers // Apr 2012

    Performance Gains in Conjugate Gradient Computation With Linearly Connected GPU Multiprocessors

    Conjugate gradient is an important iterative method used for solving least squares problems. It is compute-bound and generally involves only simple matrix computations. One would expect that the authors could fully parallelize such computation on the GPU architecture with multiple Stream Multiprocessors (SMs), each consisting of many SIMD processing units....

    Provided By Harvard University

  • White Papers // Apr 2012

    Learning Is Change in Knowledge: Knowledge-Based Security for Dynamic Policies

    In systems that handle confidential information, the security policy to enforce on information frequently changes: new users join the system, old users leave, and sensitivity of data changes over time. It is challenging, yet important, to specify what it means for such systems to be secure, and to gain assurance...

    Provided By Harvard University

  • White Papers // Feb 2012

    Modeling Internet-Scale Policies for Cleaning Up Malware

    The results of the authors' experiments using ASIM indicate that when filtering wicked traffic, the best targets for intervention are a small group of the largest ASes. Specifically, they find that intervention by the top 0.2% of ASes (in terms of size) is more effective than intervention by a randomly...

    Provided By Harvard University

  • White Papers // Dec 2011

    Compressive Sensing Based Channel Feedback Protocols for Spatially-Correlated Massive Antenna Arrays

    Incorporating wireless transceivers with numerous antennas (such as Massive-MIMO) is a prospective way to increase the link capacity or enhance the energy efficiency of future communication systems. However, the benefits of such approach can be realized only when proper channel information is available at the transmitter. Since the amount of...

    Provided By Harvard University

  • White Papers // Oct 2011

    Information-Theoretic Limits of Dense Underwater Networks

    Information-theoretic throughput scaling laws are analyzed in an underwater acoustic network with n regularly located nodes on a unit square, in which both bandwidth and received signal power can be severely limited. A narrow-band model is assumed where the carrier frequency is allowed to scale as a function of n....

    Provided By Harvard University

  • White Papers // Sep 2011

    External-Memory Multimaps

    Many data structures support dictionaries, also known as maps or associative arrays, which store and manage a set of key-value pairs. A multimap is generalization that allows multiple values to be associated with the same key. For example, the inverted file data structure that is used prevalently in the infrastructure...

    Provided By Harvard University

  • White Papers // Aug 2011

    Collaborative Compressive Spectrum Sensing in a UAV Environment

    Spectrum sensing is of fundamental importance to many wireless applications including cognitive radio channel assignment and radiolocation. However, conventional spectrum sensing can be prohibitively expensive in computation and network bandwidth when the bands under scanning are wide and highly contested. In this paper, the authors propose distributed spectrum sensing with...

    Provided By Harvard University

  • White Papers // Aug 2011

    Measurement Combining and Progressive Reconstruction in Compressive Sensing

    Compressive sensing has emerged as an important new technique in signal acquisition due to the surprising property that a sparse signal can be captured from measurements obtained at a sub-Nyquist rate. The decoding cost of compressive sensing, however, grows superlinearly with the problem size. In distributed sensor systems, the aggregate...

    Provided By Harvard University

  • White Papers // Aug 2011

    Partitioned Compressive Sensing With Neighbor-Weighted Decoding

    Compressive sensing has gained momentum in recent years as an exciting new theory in signal processing with several useful applications. It states that signals known to have a sparse representation may be encoded and later reconstructed using a small number of measurements, approximately proportional to the signal's sparsity rather than...

    Provided By Harvard University

  • White Papers // Jul 2011

    DISTROY: Detecting Integrated Circuit Trojans With Compressive Measurements

    Detecting Trojans in an Integrated Circuit (IC) is an important but hard problem. A Trojan is malicious hardware - it can be extremely small in size and dormant until triggered by some unknown circuit state. To allow wake-up, a Trojan could draw a minimal amount of power, for example, to...

    Provided By Harvard University

  • White Papers // May 2011

    Provenance Integration Requires Reconciliation

    While there has been a great deal of research on provenance systems, there has been little discussion about challenges that arise when making different provenance systems interoperate. In fact, most of the literature focuses on provenance systems in isolation and does not discuss interoperability - what it means, its requirements,...

    Provided By Harvard University

  • White Papers // May 2011

    Collecting Provenance Via the Xen Hypervisor

    The Provenance Aware Storage Systems project (PASS) currently collects system-level provenance by intercepting system calls in the Linux kernel and storing the provenance in a stackable filesystem. While this approach is reasonably efficient, it suffers from two significant drawbacks: each new revision of the kernel requires reintegration of PASS changes,...

    Provided By Harvard University

  • White Papers // May 2011

    Separation-Based Joint Decoding in Compressive Sensing

    The authors introduce a joint decoding method for compressive sensing that can simultaneously exploit sparsity of individual components of a composite signal. Their method can significantly reduce the total number of variables decoded jointly by separating variables of large magnitudes in one domain and using only these variables to represent...

    Provided By Harvard University

  • White Papers // May 2011

    Provenance Map Orbiter: Interactive Exploration of Large Provenance Graphs

    Provenance systems can produce enormous provenance graphs that can be used for a variety of tasks from determining the inputs to a particular process to debugging entire workflow executions or tracking difficult-to-find dependencies. Visualization can be a useful tool to support such tasks, but graphs of such scale (thousands to...

    Provided By Harvard University

  • White Papers // May 2011

    CloudSense: Continuous Fine-Grain Cloud Monitoring With Compressive Sensing

    Continuous fine-grain status monitoring of a cloud data center enables rapid response to anomalies, but handling the resulting torrent of data poses a significant challenge. As a solution, the authors propose CloudSense, a new switch design that performs in-network compression of status streams via compressive sensing. Using MapReduce straggler detection...

    Provided By Harvard University

  • White Papers // May 2011

    Achieving High Throughput Ground-to-UAV Transport Via Parallel Links

    Wireless data transfer under high mobility, as found in Unmanned Aerial Vehicle (UAV) applications, is a challenge due to varying channel quality and extended link outages. The authors present FlowCode, an easily deployable link-layer solution utilizing multiple transmitters and receivers for the purpose of supporting existing transport protocols such as...

    Provided By Harvard University

  • White Papers // Apr 2011

    Robustness And Contagion In The International Financial Network

    Globalization has created an international financial network of countries linked by trade in goods and assets. These linkages allow for more efficient resource allocation across borders, but also create potentially hazardous financial interdependence, such as the great financial distress caused by the 2010 threat of Greece's default or the 2008...

    Provided By Harvard University

  • White Papers // Apr 2011

    Multicore OSes: Looking Forward From 1991, er, 2011

    Upcoming multicore processors, with hundreds of cores or more in a single chip, require a degree of parallel scalability that is not currently available in today's system software. Based on prior experience in the supercomputing sector, the likely trend for multicore processors is away from shared memory and toward shared...

    Provided By Harvard University

  • White Papers // Apr 2011

    Benchmarking File System Benchmarking: It is Rocket Science

    The quality of file system benchmarking has not improved in over a decade of intense research spanning hundreds of publications. Researchers repeatedly use a wide range of poorly designed benchmarks, and in most cases, develop their own ad-hoc benchmarks. The authors' community lacks a definition of what they want to...

    Provided By Harvard University

  • White Papers // Apr 2011

    Ethical Dilemmas in Take-Down Research

    The authors discuss nine ethical dilemmas which have arisen during the investigation of 'Notice and take-down' regimes for Internet content. Issues arise when balancing the desire for accurate measurement to advance the security community's understanding with the need to immediately reduce harm that is uncovered in the course of measurement....

    Provided By Harvard University

  • White Papers // Mar 2011

    PyCUDA and PyOpenCL: A Scripting-Based Approach to GPU Run-Time Code Generation

    High-performance computing has recently seen a surge of interest in heterogeneous systems, with an emphasis on modern Graphics Processing Units (GPUs). These devices offer tremendous potential for performance and efficiency in important large-scale applications of computational science. However, exploiting this potential can be challenging, as one must adapt to the...

    Provided By Harvard University

  • White Papers // Mar 2011

    The Impact of Public Information on Phishing Attack and Defense

    Attackers compromise web servers in order to host fraudulent content, such as malware and phishing websites. While the techniques used to compromise websites are widely discussed and categorized, analysis of the methods used by attackers to identify targets has remained anecdotal. In this paper, the authors study the use of...

    Provided By Harvard University

  • White Papers // Mar 2011

    Fairness And Independence: An Impossibility Theorem

    The most widely used economic models of social preferences are specified only for certain outcomes. There are two obvious methods of extending them to lotteries. If we do so by expected utility theory, so that the independence axiom is satisfied, the results imply that the resulting preferences do not exhibit...

    Provided By Harvard University

  • White Papers // Mar 2011

    Intangible Capital, Relative Asset Shortages And Bubbles

    The authors analyze an OLG economy with financial frictions and accumulation of both physical and intangible capital. The key difference between these two types of capital is that intangible capital cannot be used as collateral for borrowing. As intangibles become more important relative to physical capital in production, interest rates...

    Provided By Harvard University

  • White Papers // Feb 2011

    A Lesson From The South For Fiscal Policy In The US And Other Advanced Countries

    American fiscal policy has been procyclical: Washington wasted the expansion period 2001-2007 by running budget deficits, but by 2011 had come to feel constrained by inherited debt to withdraw fiscal stimulus. Chile has achieved countercyclical fiscal policy - saving in booms and easing in recession - during the same decade...

    Provided By Harvard University

  • White Papers // Feb 2011

    Evaluating Value-Graph Translation Validation for LLVM

    Translation validators are static analyzers that attempt to verify that program transformations preserve semantics. Normalizing translation validators do so by trying to match the value-graphs of an original function and it's transformed counterpart. In this paper, the authors present the design of such a validator for LLVM's intra-procedural optimizations, a...

    Provided By Harvard University

  • White Papers // Feb 2011

    Demographic Change And Economic Growth In South Asia

    Identifying factors that influence the pace of national economic growth is a time-worn activity of economists. Strangely, demographic change has often been absent from consideration. But new thinking and evidence have highlighted the powerful contribution that demographic change can make to economic growth, and this line of inquiry has some...

    Provided By Harvard University

  • White Papers // Feb 2011

    Bank Credit And Business Networks

    The authors construct the topology of business networks across the population of firms in an emerging economy, Pakistan, and estimate the value that membership in large yet diffuse networks brings in terms of access to bank credit and improving financial viability. They link two firms if they have a common...

    Provided By Harvard University

  • White Papers // Sep 2010

    The Regulation Of Consumer Financial Products: An Introductory Essay With Four Case Studies

    The recent financial crisis has led many to question how well businesses deliver consumer financial services and how well regulatory institutions address problems in consumer financial markets. In response, the Obama administration proposed a new agency to oversee consumer financial services, and the recently enacted Dodd-Frank Wall Street Reform and...

    Provided By Harvard University

  • White Papers // Dec 2009

    Improving QoS in BitTorrent-Like VoD Systems

    In recent years a number of research efforts have focused on effective use of P2P-based systems in providing large scale video streaming services. In particular, live streaming and Video-on-Demand (VoD) systems have attracted much interest. While previous efforts mainly focused on the common challenges faced by both types of applications,...

    Provided By Harvard University

  • White Papers // Jun 2008

    Graption: Automated Detection of P2P Applications Using Traffic Dispersion Graphs (TDGs)

    Monitoring network traffic and detecting emerging P2P applications is an increasingly challenging problem since new applications obfuscate their traffic. Despite recent efforts, the problem is not yet solved and network administrators are still looking for effective and deployable tools. In this paper, the authors address this problem using Traffic Dispersion...

    Provided By Harvard University

  • White Papers // Feb 2010

    Graption: Graph-Based P2P Traffic Classification at the Internet Backbone

    Monitoring network traffic and classifying applications are essential functions for network administrators. Current traffic classification methods can be grouped in three categories: flow-based (e.g., packet sizing/timing features), payload-based, and host-based. Methods from all three categories have limitations, especially when it comes to detecting new applications, and classifying traffic at the...

    Provided By Harvard University

  • White Papers // May 2008

    Choosing a Data Model and Query Language for Provenance

    The ancestry relationships found in provenance form a directed graph. Many provenance queries require traversal of this graph. The data and query models for provenance should directly and naturally address this graph-centric nature of provenance. To that end, the authors set out the requirements for a provenance data and query...

    Provided By Harvard University

  • White Papers // Mar 2011

    PyCUDA and PyOpenCL: A Scripting-Based Approach to GPU Run-Time Code Generation

    High-performance computing has recently seen a surge of interest in heterogeneous systems, with an emphasis on modern Graphics Processing Units (GPUs). These devices offer tremendous potential for performance and efficiency in important large-scale applications of computational science. However, exploiting this potential can be challenging, as one must adapt to the...

    Provided By Harvard University

  • White Papers // Jan 2011

    Country Diversification, Product Ubiquity, And Economic Divergence

    Countries differ markedly in the diversification of their exports. Products differ in the number of countries that export them, which the authors define as their ubiquity. They document a new stylized fact in the global pattern of exports: there is a systematic relationship between the diversification of a country's exports...

    Provided By Harvard University

  • White Papers // Nov 2010

    Generalized Pricing Formulas For Stochastic Volatility Jump Diffusion Models Applied To The Exponential Vasicek Model

    Path integral techniques for the pricing of financial options are mostly based on models that can be recast in terms of a Fokker-Planck differential equation and that, consequently, neglect jumps and only describe drift and diffusion. The authors present a method to adapt formulas for both the path-integral propagators and...

    Provided By Harvard University

  • White Papers // Apr 2011

    Robustness And Contagion In The International Financial Network

    Globalization has created an international financial network of countries linked by trade in goods and assets. These linkages allow for more efficient resource allocation across borders, but also create potentially hazardous financial interdependence, such as the great financial distress caused by the 2010 threat of Greece's default or the 2008...

    Provided By Harvard University

  • White Papers // Apr 2008

    Abnormal Traffic Detection in VoIP by Using Machine Learning Approaches

    Accurate and fast detection of abnormal traffic is of fundamental importance to VoIP security in the Next Generation Network (NGN) world. In this paper, the machine learning methods such as Decision Tree (C4.5), Naive Bayes and Support Vector Machine (SVM) were applied to identify abnormal traffic in the authors' VoIP...

    Provided By Harvard University

  • White Papers // Mar 2011

    Intangible Capital, Relative Asset Shortages And Bubbles

    The authors analyze an OLG economy with financial frictions and accumulation of both physical and intangible capital. The key difference between these two types of capital is that intangible capital cannot be used as collateral for borrowing. As intangibles become more important relative to physical capital in production, interest rates...

    Provided By Harvard University

  • White Papers // Mar 2011

    Fairness And Independence: An Impossibility Theorem

    The most widely used economic models of social preferences are specified only for certain outcomes. There are two obvious methods of extending them to lotteries. If we do so by expected utility theory, so that the independence axiom is satisfied, the results imply that the resulting preferences do not exhibit...

    Provided By Harvard University

  • White Papers // Feb 2010

    Self Control, Risk Aversion, And The Allais Paradox

    This paper develops a dual-self model that is compatible with modern dynamic macroeconomic theory and evidence, and shows how it leads to a wide range of behavioral anomalies concerning risk, including the Allais paradox. The authors calibrate the model to obtain a quantitative fit, by extending the simpler "Nightclub" model...

    Provided By Harvard University

  • White Papers // May 2010

    Required Information Release

    Many computer systems have a functional requirement to release information. Such requirements are an important part of a system's information security requirements. Current information-flow control techniques are able to reason about permitted information flows, but not required information flows. In this paper, the authors introduce and explore the specification and...

    Provided By Harvard University

  • White Papers // Feb 2011

    Demographic Change And Economic Growth In South Asia

    Identifying factors that influence the pace of national economic growth is a time-worn activity of economists. Strangely, demographic change has often been absent from consideration. But new thinking and evidence have highlighted the powerful contribution that demographic change can make to economic growth, and this line of inquiry has some...

    Provided By Harvard University

  • White Papers // Oct 2009

    The Graying Of Global Population And Its Macroeconomic Consequences

    Population aging is emerging as a major demographic trend in many countries, with potentially important implications for a variety of macroeconomic issues. Notwithstanding these challenges, population aging will likely have a comparatively modest effect on economic growth. Although the changed age distribution would be expected to cause the labor force...

    Provided By Harvard University

  • White Papers // Sep 2008

    Demographic Change And Economic Growth In Asia

    In 1994 the World Bank called East Asia's strong economic growth performance a "Miracle". Trade openness, high savings rates, human capital accumulation, and macroeconomic policy only explained part of this growth performance; the remainder was left unexplained. Research in the ensuing years has shown that when demographic change in East...

    Provided By Harvard University

  • White Papers // Sep 2008

    Population Aging And Economic Growth In Asia

    The decline in the total fertility rate between 1960 and 2005, coupled with an increase in life expectancy and the dynamic evolution of past variation in birth and death rates, is producing a significant shift in age structure in Asia. The age distribution has shifted from one with a high...

    Provided By Harvard University

  • White Papers // Dec 2010

    Efficient Semantic Communication Via Compatible Beliefs

    In previous paper, Juba and Sudan and Goldreich, Juba and Sudan considered the idea of "Semantic communication", wherein two players, a user and a server, attempt to communicate with each other without any prior common language (or communication protocol). They showed that if communication was goal-oriented and the user could...

    Provided By Harvard University

  • White Papers // Sep 2009

    From Economic Growth To Social Wellbeing: Reflecting On Urban Theories And The Opportunities Provided By Globalization To Create A Just Society In India

    Today, Globalization is described as homogenizing the world cultures, with the assumption that global capitalism has brought in its sway disintegration of nation states, increased exploitation of indigenous populations, increased inequalities between places in the same regional boundaries. The author starts by reviewing existing literature to understand their applicability in...

    Provided By Harvard University

  • White Papers // Jan 2009

    Causality-Based Versioning

    Versioning file systems provide the ability to recover from a variety of failures, including file corruption, virus and worm infestations, and user mistakes. However, using versions to recover from data-corrupting events requires a human to determine precisely which files and versions to restore. The authors can create more meaningful versions...

    Provided By Harvard University

  • White Papers // Jul 2010

    Popularity Is Everything a New Approach to Protecting Passwords From Statistical-Guessing Attacks

    The authors propose to strengthen user-selected passwords against statistical-guessing attacks by allowing users of Internet-scale systems to choose any password they want-so long as it's not already too popular with other users. They create an oracle to identify undesirably popular passwords using an existing data structure known as a count-min...

    Provided By Harvard University

  • White Papers // Jan 2011

    On the Zero-Error Capacity Threshold for Deletion Channels

    The authors consider the zero-error capacity of deletion channels. Specifically, they consider the setting where they choose a codebook C consisting of strings of n bits, and their model of the channel corresponds to an adversary who may delete up to pn of these bits for a constant p. Their...

    Provided By Harvard University

  • White Papers // Sep 2009

    An Improved Analysis of the Lossy Difference Aggregator

    The authors provide a detailed analysis of the Lossy Difference Aggregator, a recently developed data structure for measuring latency in a router environment where packet losses can occur. Their analysis provides stronger performance bounds than those given originally, and leads one to a model for how to optimize the parameters...

    Provided By Harvard University

  • White Papers // Jun 2009

    Some Open Questions Related to Cuckoo Hashing

    Hash-based data structures and algorithms are currently a booming industry in the Internet, particularly for applications related to measurement, monitoring, and security. Hash tables and related structures, such as Bloom filters and their derivatives, are used billions of times a day, and new uses keep proliferating. Indeed, one of the...

    Provided By Harvard University

  • White Papers // Sep 2008

    On the Performance of Multiple Choice Hash Tables With Moves on Deletes and Inserts

    High-performance hashing has become a fundamental subroutine for a wide variety of high performance network processing tasks, including header lookup for routing, measurement, and monitoring. In considering hashing alternatives, many possible considerations arise, perhaps the most important being how much time is spent performing lookup, insert, and delete operations, and...

    Provided By Harvard University

  • White Papers // Jun 2008

    A Survey of Results for Deletion Channels and Related Synchronization Channels

    The binary symmetric channel, where each bit is independently received in error with probability p, and the binary erasure channel, where each bit is erased with probability p, enjoy a long and rich history. Shannon developed the fundamental results on the capacity of such channels in the 1940's, and in...

    Provided By Harvard University

  • White Papers // May 2011

    Provenance Integration Requires Reconciliation

    While there has been a great deal of research on provenance systems, there has been little discussion about challenges that arise when making different provenance systems interoperate. In fact, most of the literature focuses on provenance systems in isolation and does not discuss interoperability - what it means, its requirements,...

    Provided By Harvard University

  • White Papers // May 2011

    Provenance Map Orbiter: Interactive Exploration of Large Provenance Graphs

    Provenance systems can produce enormous provenance graphs that can be used for a variety of tasks from determining the inputs to a particular process to debugging entire workflow executions or tracking difficult-to-find dependencies. Visualization can be a useful tool to support such tasks, but graphs of such scale (thousands to...

    Provided By Harvard University

  • White Papers // May 2011

    Collecting Provenance Via the Xen Hypervisor

    The Provenance Aware Storage Systems project (PASS) currently collects system-level provenance by intercepting system calls in the Linux kernel and storing the provenance in a stackable filesystem. While this approach is reasonably efficient, it suffers from two significant drawbacks: each new revision of the kernel requires reintegration of PASS changes,...

    Provided By Harvard University

  • White Papers // Apr 2011

    Benchmarking File System Benchmarking: It is Rocket Science

    The quality of file system benchmarking has not improved in over a decade of intense research spanning hundreds of publications. Researchers repeatedly use a wide range of poorly designed benchmarks, and in most cases, develop their own ad-hoc benchmarks. The authors' community lacks a definition of what they want to...

    Provided By Harvard University

  • White Papers // Apr 2011

    Multicore OSes: Looking Forward From 1991, er, 2011

    Upcoming multicore processors, with hundreds of cores or more in a single chip, require a degree of parallel scalability that is not currently available in today's system software. Based on prior experience in the supercomputing sector, the likely trend for multicore processors is away from shared memory and toward shared...

    Provided By Harvard University

  • White Papers // Feb 2010

    Towards Query Interoperability: PASSing PLUS

    The authors describe their experiences importing PASS provenance into PLUS. Although both systems import and export provenance that conforms to the Open Provenance Model (OPM), the two systems vary greatly with respect to the granularity of provenance captured, how much semantic knowledge the system contributes, and the completeness of provenance...

    Provided By Harvard University

  • White Papers // Feb 2010

    Tracking Back References in a Write-Anywhere File System

    Many file systems reorganize data on disk, for example to defragment storage, shrink volumes, or migrate data between different classes of storage. Advanced file system features such as snapshots, writable clones, and deduplication make these tasks complicated, as moving a single block may require finding and updating dozens, or even...

    Provided By Harvard University

  • White Papers // Apr 2009

    A Class of Bi-Directional Multi-Relay Protocols

    In a bi-directional relay channel, two nodes wish to exchange independent messages over a shared wireless half-duplex channel with the help of relays. Recent work has considered information theoretic limits of the bi-directional relay channel with a single relay. In this paper, the authors consider bidirectional relaying with multiple relays....

    Provided By Harvard University

  • White Papers // Jan 2011

    A Non-Work-Conserving Operating System Scheduler for SMT Processors

    Simultaneous Multi-Threading (SMT) processors run multiple threads simultaneously on a single processing core. Because concurrent threads compete for the processor's shared resources, non-work-conserving scheduling, i.e., running fewer threads than the processor allows even if there are threads ready to run, can often improve performance. Nevertheless, conventional operating systems do not...

    Provided By Harvard University

  • White Papers // Jan 2011

    Abstract Predicates and Mutable ADTs in Hoare Type Theory

    Hoare Type Theory (HTT) combines a dependently typed, higher-order language with monadically-encapsulated, stateful computations. The type system incorporates pre- and post-conditions, in a fashion similar to Hoare and Separation Logic, so that programmers can modularly specify the requirements and effects of computations within types. This paper extends HTT with quantification...

    Provided By Harvard University

  • White Papers // Oct 2009

    Strategic Advantage: Why America Should Care About Cybersecurity

    The internet is an interconnected series of networks - where it is difficult to determine where private security threats end and public ones begin. These networks deliver power and water to the people households and businesses, enable one to access their bank accounts from almost any city in the world,...

    Provided By Harvard University

  • White Papers // Feb 2011

    Evaluating Value-Graph Translation Validation for LLVM

    Translation validators are static analyzers that attempt to verify that program transformations preserve semantics. Normalizing translation validators do so by trying to match the value-graphs of an original function and it's transformed counterpart. In this paper, the authors present the design of such a validator for LLVM's intra-procedural optimizations, a...

    Provided By Harvard University

  • White Papers // May 2009

    Certified Web Services in Ynot

    In this paper, the authors explains that it is possible to implement certified web systems in a way not much different from writing Standard ML or Haskell code, including use of imperative features like pointers, files, and socket I/O. They present a web-based course grade-book application developed with Ynot, a...

    Provided By Harvard University