OpenRaiser/Intern-Atlas huggingface dataset:
Dealing with Sparse Document and Topic Representations: Lab Report for CHiC 2012
Venue: arXiv cs.IR 2012
Year: 2012

We will report on the participation of GESIS at the first CHiC workshop (Cultural Heritage in CLEF). Being held for the first time, no prior experience with the new data set, a document dump of Europeana with ca. 23 million documents, exists. The most prominent issues that arose from pretests with this test collection were the very unspecific topics and sparse document representations. Only half of the topics (26/50) contained a description and the titles were usually short with just around two words. Therefore we focused on three different term suggestion and query expansion mechanisms to surpass the sparse topical description. We used two methods that build on concept extraction from Wikipedia and on a method that applied co-occurrence statistics on the available Europeana corpus. In the following paper we will present the approaches and preliminary results from their assessments.
Network Coding Based on Chinese Remainder Theorem
Venue: arXiv cs.IT 2012
Year: 2012

Random linear network code has to sacrifice part of bandwidth to transfer the coding vectors, thus a head of size k log|T| is appended to each packet. We present a distributed random network coding approach based on the Chinese remainder theorem for general multicast networks. It uses a couple of modulus as the head, thus reduces the size of head to O(log k). This makes it more suitable for scenarios where the number of source nodes is large and the bandwidth is limited. We estimate the multicast rate and show it is satisfactory in performance for randomly designed networks.
On the Capacity of the Cognitive Interference Channel with a Common Cognitive Message
Venue: arXiv cs.IT 2012
Year: 2012

In this paper the cognitive interference channel with a common message, a variation of the classical cognitive interference channel in which the cognitive message is decoded at both receivers, is studied. For this channel model new outer and inner bounds are developed as well as new capacity results for both the discrete memoryless and the Gaussian case. The outer bounds are derived using bounding techniques originally developed by Sato for the classical interference channel and Nair and El Gamal for the broadcast channel. A general inner bound is obtained combining rate-splitting, superposition coding and binning. Inner and outer bounds are shown to coincide in the "very strong interference" and the "primary decodes cognitive" regimes. The first regime consists of channels in which there is no loss of optimality in having both receivers decode both messages while in the latter regime interference pre-cancellation at the cognitive receiver achieves capacity. Capacity for the Gaussian channel is shown to within a constant additive gap and a constant multiplicative factor.
Coordination in Network Security Games: a Monotone Comparative Statics Approach
Venue: arXiv cs.GT 2012
Year: 2012

Malicious softwares or malwares for short have become a major security threat. While originating in criminal behavior, their impact are also influenced by the decisions of legitimate end users. Getting agents in the Internet, and in networks in general, to invest in and deploy security features and protocols is a challenge, in particular because of economic reasons arising from the presence of network externalities. In this paper, we focus on the question of incentive alignment for agents of a large network towards a better security. We start with an economic model for a single agent, that determines the optimal amount to invest in protection. The model takes into account the vulnerability of the agent to a security breach and the potential loss if a security breach occurs. We derive conditions on the quality of the protection to ensure that the optimal amount spent on security is an increasing function of the agent's vulnerability and potential loss. We also show that for a large class of risks, only a small fraction of the expected loss should be invested. Building on these results, we study a network of interconnected agents subject to epidemic risks. We derive conditions to ensure that the incentives of all agents are aligned towards a better security. When agents are strategic, we show that security investments are always socially inefficient due to the network externalities. Moreover alignment of incentives typically implies a coordination problem, leading to an equilibrium with a very high price of anarchy.
Learning sparse messages in networks of neural cliques
Venue: arXiv cs.NE 2012
Year: 2012

An extension to a recently introduced binary neural network is proposed in order to allow the learning of sparse messages, in large numbers and with high memory efficiency. This new network is justified both in biological and informational terms. The learning and retrieval rules are detailed and illustrated by various simulation results.
Injecting Uncertainty in Graphs for Identity Obfuscation
Venue: arXiv cs.DB 2012
Year: 2012

Data collected nowadays by social-networking applications create fascinating opportunities for building novel services, as well as expanding our understanding about social structures and their dynamics. Unfortunately, publishing social-network graphs is considered an ill-advised practice due to privacy concerns. To alleviate this problem, several anonymization methods have been proposed, aiming at reducing the risk of a privacy breach on the published data, while still allowing to analyze them and draw relevant conclusions. In this paper we introduce a new anonymization approach that is based on injecting uncertainty in social graphs and publishing the resulting uncertain graphs. While existing approaches obfuscate graph data by adding or removing edges entirely, we propose using a finer-grained perturbation that adds or removes edges partially: this way we can achieve the same desired level of obfuscation with smaller changes in the data, thus maintaining higher utility. Our experiments on real-world networks confirm that at the same level of identity obfuscation our method provides higher usefulness than existing randomized methods that publish standard graphs.
Transaction Log Based Application Error Recovery and Point In-Time Query
Venue: arXiv cs.DB 2012
Year: 2012

Database backups have traditionally been used as the primary mechanism to recover from hardware and user errors. High availability solutions maintain redundant copies of data that can be used to recover from most failures except user or application errors. Database backups are neither space nor time efficient for recovering from user errors which typically occur in the recent past and affect a small portion of the database. Moreover periodic full backups impact user workload and increase storage costs. In this paper we present a scheme that can be used for both user and application error recovery starting from the current state and rewinding the database back in time using the transaction log. While we provide a consistent view of the entire database as of a point in time in the past, the actual prior versions are produced only for data that is accessed. We make the as of data accessible to arbitrary point in time queries by integrating with the database snapshot feature in Microsoft SQL Server.
ODYS: A Massively-Parallel Search Engine Using a DB-IR Tightly-Integrated Parallel DBMS
Venue: arXiv cs.DB 2012
Year: 2012

Recently, parallel search engines have been implemented based on scalable distributed file systems such as Google File System. However, we claim that building a massively-parallel search engine using a parallel DBMS can be an attractive alternative since it supports a higher-level (i.e., SQL-level) interface than that of a distributed file system for easy and less error-prone application development while providing scalability. In this paper, we propose a new approach of building a massively-parallel search engine using a DB-IR tightly-integrated parallel DBMS and demonstrate its commercial-level scalability and performance. In addition, we present a hybrid (i.e., analytic and experimental) performance model for the parallel search engine. We have built a five-node parallel search engine according to the proposed architecture using a DB-IR tightly-integrated DBMS. Through extensive experiments, we show the correctness of the model by comparing the projected output with the experimental results of the five-node engine. Our model demonstrates that ODYS is capable of handling 1 billion queries per day (81 queries/sec) for 30 billion web pages by using only 43,472 nodes with an average query response time of 211 ms, which is equivalent to or better than those of commercial search engines. We also show that, by using twice as many (86,944) nodes, ODYS can provide an average query response time of 162 ms, which is significantly lower than those of commercial search engines.
Cooperative Communication Based on Random Beamforming Strategy in Wireless Sensor Networks
Venue: arXiv cs.NI 2012
Year: 2012

This paper presents a two-phase cooperative communication strategy and an optimal power allocation strategy to transmit sensor observations to a fusion center in a large-scale sensor network. Outage probability is used to evaluate the performance of the proposed system. Simulation results demonstrate that: 1) when signal-to-noise ratio is low, the performance of the proposed system is better than that of the multiple-input and multiple-output system over uncorrelated slow fading Rayleigh channels; 2) given the transmission rate and the total transmission SNR, there exists an optimal power allocation that minimizes the outage probability; 3) on correlated slow fading Rayleigh channels, channel correlation will degrade the system performance in linear proportion to the correlation level.
An Open Framework for Extensible Multi-Stage Bioinformatics Software
Venue: arXiv cs.SE 2012
Year: 2012

In research labs, there is often a need to customise software at every step in a given bioinformatics workflow, but traditionally it has been difficult to obtain both a high degree of customisability and good performance. Performance-sensitive tools are often highly monolithic, which can make research difficult. We present a novel set of software development principles and a bioinformatics framework, Friedrich, which is currently in early development. Friedrich applications support both early stage experimentation and late stage batch processing, since they simultaneously allow for good performance and a high degree of flexibility and customisability. These benefits are obtained in large part by basing Friedrich on the multiparadigm programming language Scala. We present a case study in the form of a basic genome assembler and its extension with new functionality. Our architecture has the potential to greatly increase the overall productivity of software developers and researchers in bioinformatics.
On Multisequences and their extensions
Venue: arXiv cs.CR 2012
Year: 2012

In this paper we deal with the dimension of multisequences and related properties. For a given multisequence W and an m tuple of positive integers R, we define the R extension of W. Further we count the number of multisequences W whose R extensions have maximum dimension and give an algorithm to derive such multisequences. We then go on to use this theory to count the number of Linear Feedback Shift Register(LFSR) configurations with multi input multi output delay blocks for any given primitive characteristic polynomial and also to design such LFSRs. Further, we use the result on multisequences to count the number of Hankel matrices of any given dimension.
Compressive Source Separation: Theory and Methods for Hyperspectral Imaging
Venue: arXiv cs.IT 2012
Year: 2012

With the development of numbers of high resolution data acquisition systems and the global requirement to lower the energy consumption, the development of efficient sensing techniques becomes critical. Recently, Compressed Sampling (CS) techniques, which exploit the sparsity of signals, have allowed to reconstruct signal and images with less measurements than the traditional Nyquist sensing approach. However, multichannel signals like Hyperspectral images (HSI) have additional structures, like inter-channel correlations, that are not taken into account in the classical CS scheme. In this paper we exploit the linear mixture of sources model, that is the assumption that the multichannel signal is composed of a linear combination of sources, each of them having its own spectral signature, and propose new sampling schemes exploiting this model to considerably decrease the number of measurements needed for the acquisition and source separation. Moreover, we give theoretical lower bounds on the number of measurements required to perform reconstruction of both the multichannel signal and its sources. We also proposed optimization algorithms and extensive experimentation on our target application which is HSI, and show that our approach recovers HSI with far less measurements and computational effort than traditional CS approaches.
On Dynamical Cournot Game on a Graph
Venue: arXiv cs.GT 2012
Year: 2012

Cournot dynamical game is studied on a graph. The stability of the system is studied. Prisoner's dilemma game is used to model natural gas transmission.
In the Face (book) of Social Learning
Venue: arXiv cs.CY 2012
Year: 2012

Social networks have risen to prominence over the last years as the predominant form of electronic interaction between individuals. In an attempt to harness the power of the large user base which they have managed to attract, this study proposes an e-learning prototype which integrates concepts of the social and semantic web. A selected set of services are deployed which have been scientifically proven to positively impact the learning process of users via electronic means. The integrability of these services into a social network platform application is visualized through an exploratory prototype. The Graphical User Interface (GUI) which is developed to implement these key features is in alignment with User-Centered principles. The designed prototype proves that a number of services can be integrated in a user-friendly application and can potentially serve to gain feedback regarding additional aspects that should be included.
Parameterized Concurrent Multi-Party Session Types
Venue: arXiv cs.PL 2012
Year: 2012

Session types have been proposed as a means of statically verifying implementations of communication protocols. Although prior work has been successful in verifying some classes of protocols, it does not cope well with parameterized, multi-actor scenarios with inherent asynchrony. For example, the sliding window protocol is inexpressible in previously proposed session type systems. This paper describes System-A, a new typing language which overcomes many of the expressiveness limitations of prior work. System-A explicitly supports asynchrony and parallelism, as well as multiple forms of parameterization. We define System-A and show how it can be used for the static verification of a large class of asynchronous communication protocols.
A Provenance Tracking Model for Data Updates
Venue: arXiv cs.DC 2012
Year: 2012

For data-centric systems, provenance tracking is particularly important when the system is open and decentralised, such as the Web of Linked Data. In this paper, a concise but expressive calculus which models data updates is presented. The calculus is used to provide an operational semantics for a system where data and updates interact concurrently. The operational semantics of the calculus also tracks the provenance of data with respect to updates. This provides a new formal semantics extending provenance diagrams which takes into account the execution of processes in a concurrent setting. Moreover, a sound and complete model for the calculus based on ideals of series-parallel DAGs is provided. The notion of provenance introduced can be used as a subjective indicator of the quality of data in concurrent interacting systems.
Hamilton Operators, Discrete Symmetries, Brute Force and SymbolicC++
Venue: arXiv cs.MS 2012
Year: 2012

To find the discrete symmetries of a Hamilton operator $\hat H$ is of central importance in quantum theory. Here we describe and implement a brute force method to determine the discrete symmetries given by permutation matrices for Hamilton operators acting in a finite-dimensional Hilbert space. Spin and Fermi systems are considered as examples. A computer algebra implementation in SymbolicC++ is provided.
User Manual for the Complex Conjugate Gradient Methods Library CCGPAK 2.0
Venue: arXiv cs.MS 2012
Year: 2012

This manual describes the library of conjugate gradients codes CCGPAK, which solves system of complex linear system of equations. The library is written in FORTRAN90 and is highly portable. The codes are general and provide mechanism for matrix times vector multiplication which is separated from the conjugate gradient iterations itself. It is simple to switch between single and double precisions. All codes follow the same naming conventions.
A Note on Limited Pushdown Alphabets in Stateless Deterministic Pushdown Automata
Venue: arXiv cs.FL 2012
Year: 2012

Recently, an infinite hierarchy of languages accepted by stateless deterministic pushdown automata has been established based on the number of pushdown symbols. However, the witness language for the n-th level of the hierarchy is over an input alphabet with 2(n-1) elements. In this paper, we improve this result by showing that a binary alphabet is sufficient to establish this hierarchy. As a consequence of our construction, we solve the open problem formulated by Meduna et al. Then we extend these results to m-state realtime deterministic pushdown automata, for all m at least 1. The existence of such a hierarchy for m-state deterministic pushdown automata is left open.
Precoder Design for Orthogonal Space-Time Block Coding based Cognitive Radio with Polarized Antennas
Venue: arXiv cs.NI 2012
Year: 2012

The spectrum sharing has recently passed into a mainstream Cognitive Radio (CR) strategy. We investigate the core issue in this strategy: interference mitigation at Primary Receiver (PR).We propose a linear precoder design which aims at alleviating the interference caused by Secondary User (SU) from the source for Orthogonal Space-Time Block Coding (OSTBC) based CR. We resort to Minimum Variance (MV) approach to contrive the precoding matrix at Secondary Transmitter (ST) in order to maximize the Signal to Noise Ratio (SNR) at Secondary Receiver (SR) on the premise that the orthogonality of OSTBC is kept, the interference introduced to Primary Link (PL) by Secondary Link (SL) is maintained under a tolerable level and the total transmitted power constraint at ST is satisfied. Moreover, the selection of polarization mode for SL is incorporated in the precoder design. In order to provide an analytic solution with low computational cost, we put forward an original precoder design algorithm which exploits an auxiliary variable to treat the optimization problem with a mixture of linear and quadratic constraints. Numerical results demonstrate that our proposed precoder design enable SR to have an agreeable SNR on the prerequisite that the interference at PR is maintained below the threshold.
A Novel Data Hiding Scheme for Binary Images
Venue: arXiv cs.CR 2012
Year: 2012

This paper presents a new scheme for hiding a secret message in binary images. Given m*n cover image block, the new scheme can conceal as many as log(m*n +1) bits of data in block, by changing at most one bit in the block. The hiding ability of the new scheme is the same as Chang et al.'s scheme and higher than Tseng et al.'s scheme. Additionally, the security of the new scheme is higher than the two above schemes.
Monoidal computer I: Basic computability by string diagrams
Venue: arXiv cs.LO 2012
Year: 2012

We present a new model of computation, described in terms of monoidal categories. It conforms the Church-Turing Thesis, and captures the same computable functions as the standard models. It provides a succinct categorical interface to most of them, free of their diverse implementation details, using the ideas and structures that in the meantime emerged from research in semantics of computation and programming. The salient feature of the language of monoidal categories is that it is supported by a sound and complete graphical formalism, string diagrams, which provide a concrete and intuitive interface for abstract reasoning about computation. The original motivation and the ultimate goal of this effort is to provide a convenient high level programming language for a theory of computational resources, such as one-way functions, and trapdoor functions, by adopting the methods for hiding the low level implementation details that emerged from practice. In the present paper, we make a first step towards this ambitious goal, and sketch a path to reach it. This path is pursued in three sequel papers, that are in preparation.
General Managers Role in Balancing Subsidiary Between Internal Competition and Knowledge Sharing
Venue: arXiv cs.SI 2012
Year: 2012

In our work we saw that during the last decades the environment that the MNCs operate in has changed becoming more volatile and less pacedly growing. In this environment the MNCs themselves have become more complex and also flexible. We found that MNCs are essentially three dimensional, that is, they organize around product, functional and geographical dimensions and exhibit characteristics that having a common origin can be applied along any one dimension. Therefore we depicted MNCs as having a divergent, partially overlapping structural map. On that map there can, for instance, be functionally oriented Centers Of Excellence, product dimension World Product Mandates, and for capturing synergy of a big set of operations country dimension based arrangements. Analyzing the development of organizational aspects of MNC theories we saw different bodies of work pointing to a similar direction. We followed developments of concepts Heterarchy, Transnational (and the related Individualized Corporation), works of interorganizational theories school (the multicentered MNC), works considering autonomous strategic decisions, and works originating from subsidiary (host) country research. In addition to the structural developments mentioned earlier these works also point to a need to empower the frontline units. Outlining our research problem the conceptualization of MNCs as operating (competitive) internal markets was shown to rely on entrepreneurial, initiative taking behavior and result in the development of the subsidiary. We classified the subsidiaries first selecting operations substantial enough and then differentiating them based on the autonomy level, as it has implications for the types of initiatives taken.