OpenRaiser/Intern-Atlas huggingface dataset:
Gamification, virality and retention in educational online platform. Measurable indicators and market entry strategy
Venue: arXiv cs.CY 2014
Year: 2014

The paper describes gamification, virality and retention in the freemium educational online platform with 40,000 users as an example. Relationships between virality and retention parameters as measurable metrics are calculated and discussed using real examples. Virality and monetization can be both competing and complementary mechanisms for the system growth. The K-growth factor, which combines both virality and retention, is proposed as the metrics of the overall freemium system performance in terms of the user base growth. This approach can be tested using a small number of users to assess the system potential performance. If the K-growth factor is less than one, the product needs further development. If the K-growth factor it is greater than one, the system retains existing and attracts new users, thus a large scale market launch can be successful.
Converting a Systems Dynamic Model to an Agent-based model for studying the Bicoid morphogen gradient in Drosophila embryo
Venue: arXiv cs.MA 2014
Year: 2014

The concentration gradient of the Bicoid morphogen, which is established during the early stages of a Drosophila melanogaster embryonic development, determines the differential spatial patterns of gene expression and subsequent cell fate determination. This is mainly achieved by diffusion elicited by the different concentrations of the Bicoid protein in the embryo. Such chemical dynamic progress can be simulated by stochastic models, particularly the Gillespie alogrithm. However, as with various modelling approaches in biology, each technique involves drawing assumptions and reducing the model complexity sometimes limiting the model capability. This is mainly due to the complexity of the software modelling approaches to construct these models. Agent-based modelling is a technique which is becoming increasingly popular for modelling the behaviour of individual molecules or cells in computational biology. This paper attempts to compare these two popular modelling techniques of stochastic and agent-based modelling to show how the model can be studied in detail using the different approaches. This paper presents how to use these techniques with the advantages and disadvantages of using either of these. Through various comparisons, such as computation complexity and results obtained, we show that although the same model is implemented, both approaches can give varying results. The results of the paper show that the stochastic model is able to give smoother results compared to the agent-based model which may need further analysis at a later stage. We discuss the reasons for these results and how these could be rectified in systems biology research.
Computational Model to Generate Case-Inflected Forms of Masculine Nouns for Word Search in Sanskrit E-Text
Venue: arXiv cs.CL 2014
Year: 2014

The problem of word search in Sanskrit is inseparable from complexities that include those caused by euphonic conjunctions and case-inflections. The case-inflectional forms of a noun normally number 24 owing to the fact that in Sanskrit there are eight cases and three numbers-singular, dual and plural. The traditional method of generating these inflectional forms is rather elaborate owing to the fact that there are differences in the forms generated between even very similar words and there are subtle nuances involved. Further, it would be a cumbersome exercise to generate and search for 24 forms of a word during a word search in a large text, using the currently available case-inflectional form generators. This study presents a new approach to generating case-inflectional forms that is simpler to compute. Further, an optimized model that is sufficient for generating only those word forms that are required in a word search and is more than 80% efficient compared to the complete case-inflectional forms generator, is presented in this study for the first time.
A perceptual hash function to store and retrieve large scale DNA sequences
Venue: arXiv cs.CE 2014
Year: 2014

This paper proposes a novel approach for storing and retrieving massive DNA sequences.. The method is based on a perceptual hash function, commonly used to determine the similarity between digital images, that we adapted for DNA sequences. Perceptual hash function presented here is based on a Discrete Cosine Transform Sign Only (DCT-SO). Each nucleotide is encoded as a fixed gray level intensity pixel and the hash is calculated from its significant frequency characteristics. This results to a drastic data reduction between the sequence and the perceptual hash. Unlike cryptographic hash functions, perceptual hashes are not affected by "avalanche effect" and thus can be compared. The similarity distance between two hashes is estimated with the Hamming Distance, which is used to retrieve DNA sequences. Experiments that we conducted show that our approach is relevant for storing massive DNA sequences, and retrieving them.
A nonlinear tracking algorithm with range-rate measurements based on unbiased measurement conversion
Venue: arXiv cs.SY 2014
Year: 2014

The three-dimensional CMKF-U with only position measurements is extended to solve the nonlinear tracking problem with range-rate measurements in this paper. A pseudo measurement is constructed by the product of range and range-rate measurements to reduce the high nonlinearity of the range-rate measurements with respect to the target state; then the mean and covariance of the converted measurement errors are derived by the measurement conditioned method, showing better consistency than the transitional nested conditioning method; finally, the sequential filter was used to process the converted position and range-rate measurements sequentially to reduce the approximation error in the second-order EKF. Monte Carlo simulations show that the performance of the new tracking algorithm is better than the traditional one based on CMKF-D.
Optimal Triggering of Networked Control Systems
Venue: arXiv cs.SY 2014
Year: 2014

The problem of resource allocation of nonlinear networked control systems is investigated, where, unlike the well discussed case of triggering for stability, the objective is optimal triggering. An approximate dynamic programming approach is developed for solving problems with fixed final times initially and then it is extended to infinite horizon problems. Different cases including Zero-Order-Hold, Generalized Zero-Order-Hold, and stochastic networks are investigated. Afterwards, the developments are extended to the case of problems with unknown dynamics and a model-free scheme is presented for learning the (approximate) optimal solution. After detailed analyses of convergence, optimality, and stability of the results, the performance of the method is demonstrated through different numerical examples.
Multiobjective Optimization of Classifiers by Means of 3-D Convex Hull Based Evolutionary Algorithm
Venue: arXiv cs.NE 2014
Year: 2014

Finding a good classifier is a multiobjective optimization problem with different error rates and the costs to be minimized. The receiver operating characteristic is widely used in the machine learning community to analyze the performance of parametric classifiers or sets of Pareto optimal classifiers. In order to directly compare two sets of classifiers the area (or volume) under the convex hull can be used as a scalar indicator for the performance of a set of classifiers in receiver operating characteristic space. Recently, the convex hull based multiobjective genetic programming algorithm was proposed and successfully applied to maximize the convex hull area for binary classification problems. The contribution of this paper is to extend this algorithm for dealing with higher dimensional problem formulations. In particular, we discuss problems where parsimony (or classifier complexity) is stated as a third objective and multi-class classification with three different true classification rates to be maximized. The design of the algorithm proposed in this paper is inspired by indicator-based evolutionary algorithms, where first a performance indicator for a solution set is established and then a selection operator is designed that complies with the performance indicator. In this case, the performance indicator will be the volume under the convex hull. The algorithm is tested and analyzed in a proof of concept study on different benchmarks that are designed for measuring its capability to capture relevant parts of a convex hull. Further benchmark and application studies on email classification and feature selection round up the analysis and assess robustness and usefulness of the new algorithm in real world settings.
ConGUSTo: (HT)Condor Graphical Unified Supervising Tool
Venue: arXiv cs.DC 2014
Year: 2014

HTCondor is a distributed job scheduler developed by the University of Wisconsin-Madison, which allows users to run their applications in other users' machines when they are not being used, thus providing a considerably increase in the overall computational power and a more efficient use of the computing resources. Our institution has been successfully using HTCondor for more than ten years, and HTCondor is nowadays the most used Supercomputing resource we have. Although HTCondor provides a wide range of tools and options for its management and administration, there are currently no tools that can show detailed usage information and statistics in a clear, easy to interpret, interactive set of graphics displays. For this reason, we have developed ConGUSTo, a web-based tool that allows to collect HTCondor usage and statistics data in an easy way, and present them using a variety of tabular and graphics charts.
Dense Testers: Almost Linear Time and Locally Explicit Constructions
Venue: arXiv cs.DM 2014
Year: 2014

We develop a new notion called $(1-ε)$-tester for a set $M$ of functions $f:A\to C$. A $(1-ε)$-tester for $M$ maps each element $a\in A$ to a finite number of elements $B_a=\{b_1,\ldots,b_t\}\subset B$ in a smaller sub-domain $B\subset A$ where for every $f\in M$ if $f(a)\not=0$ then $f(b)\not=0$ for at least $(1-ε)$ fraction of the elements $b$ of $B_a$. I.e., if $f(a)\not=0$ then $\Pr_{b\in B_a}[f(b)\not=0]\ge 1-ε$. The {\it size} of the $(1-ε)$-tester is $\max_{a\in A}|B_a|$ and the goal is to minimize this size, construct $B_a$ in deterministic almost linear time and access and compute each map in poly-log time. We use tools from elementary algebra and algebraic function fields to build $(1-ε)$-testers of small size in deterministic almost linear time. We also show that our constructions are locally explicit, i.e., one can find any entry in the construction in time poly-log in the size of the construction and the field size. We also prove lower bounds that show that the sizes of our testers and the densities are almost optimal. Testers were used in [Bshouty, Testers and its application, ITCS 2014] to construct almost optimal perfect hash families, universal sets, cover-free families, separating hash functions, black box identity testing and hitting sets. The dense testers in this paper shows that such constructions can be done in almost linear time, are locally explicit and can be made to be dense.
A 237 Gbps Unrolled Hardware Polar Decoder
Venue: arXiv cs.AR 2014
Year: 2014

In this letter we present a new architecture for a polar decoder using a reduced complexity successive cancellation decoding algorithm. This novel fully-unrolled, deeply-pipelined architecture is capable of achieving a coded throughput of over 237 Gbps for a (1024,512) polar code implemented using an FPGA. This decoder is two orders of magnitude faster than state-of-the-art polar decoders.
A Simple and Efficient Method To Generate Word Sense Representations
Venue: arXiv cs.CL 2014
Year: 2014

Distributed representations of words have boosted the performance of many Natural Language Processing tasks. However, usually only one representation per word is obtained, not acknowledging the fact that some words have multiple meanings. This has a negative effect on the individual word representations and the language model as a whole. In this paper we present a simple model that enables recent techniques for building word vectors to represent distinct senses of polysemic words. In our assessment of this model we show that it is able to effectively discriminate between words' senses and to do so in a computationally efficient manner.
Local weak form meshless techniques based on the radial point interpolation (RPI) method and local boundary integral equation (LBIE) method to evaluate European and American options
Venue: arXiv cs.CE 2014
Year: 2014

For the first time in mathematical finance field, we propose the local weak form meshless methods for option pricing; especially in this paper we select and analysis two schemes of them named local boundary integral equation method (LBIE) based on moving least squares approximation (MLS) and local radial point interpolation (LRPI) based on Wu's compactly supported radial basis functions (WCS-RBFs). LBIE and LRPI schemes are the truly meshless methods, because, a traditional non-overlapping, continuous mesh is not required, either for the construction of the shape functions, or for the integration of the local sub-domains. In this work, the American option which is a free boundary problem, is reduced to a problem with fixed boundary using a Richardson extrapolation technique. Then the $θ$-weighted scheme is employed for the time derivative. Stability analysis of the methods is analyzed and performed by the matrix method. In fact, based on an analysis carried out in the present paper, the methods are unconditionally stable for implicit Euler (θ= 0) and Crank-Nicolson (θ= 0.5) schemes. It should be noted that LBIE and LRPI schemes lead to banded and sparse system matrices. Therefore, we use a powerful iterative algorithm named the Bi-conjugate gradient stabilized method (BCGSTAB) to get rid of this system. Numerical experiments are presented showing that the LBIE and LRPI approaches are extremely accurate and fast.
Annotation as a New Paradigm in Research Archiving
Venue: arXiv cs.DL 2014
Year: 2014

We outline a paradigm to preserve results of digital scholarship, whether they are query results, feature values, or topic assignments. This paradigm is characterized by using annotations as multifunctional carriers and making them portable. The testing grounds we have chosen are two significant enterprises, one in the history of science, and one in Hebrew scholarship. The first one (CKCC) focuses on the results of a project where a Dutch consortium of universities, research institutes, and cultural heritage institutions experimented for 4 years with language techniques and topic modeling methods with the aim to analyze the emergence of scholarly debates. The data: a complex set of about 20.000 letters. The second one (DTHB) is a multi-year effort to express the linguistic features of the Hebrew bible in a text database, which is still growing in detail and sophistication. Versions of this database are packaged in commercial bible study software. We state that the results of these forms of scholarship require new knowledge management and archive practices. Only when researchers can build efficiently on each other's (intermediate) results, they can achieve the aggregations of quality data by which new questions can be answered, and hidden patterns visualized. Archives are required to find a balance between preserving authoritative versions of sources and supporting collaborative efforts in digital scholarship. Annotations are promising vehicles for preserving and reusing research results. Keywords annotation, portability, archiving, queries, features, topics, keywords, Republic of Letters, Hebrew text databases.
A Note on the Assignment Problem with Uniform Preferences
Venue: arXiv cs.GT 2014
Year: 2014

Motivated by a problem of scheduling unit-length jobs with weak preferences over time-slots, the random assignment problem (also called the house allocation problem) is considered on a uniform preference domain. For the subdomain in which preferences are strict except possibly for the class of unacceptable objects, Bogomolnaia and Moulin characterized the probabilistic serial mechanism as the only mechanism satisfying equal treatment of equals, strategyproofness, and ordinal efficiency. The main result in this paper is that the natural extension of the probabilistic serial mechanism to the domain of weak, but uniform, preferences fails strategyproofness, but so does every other mechanism that is ordinally efficient and treats equals equally. If envy-free assignments are required, then any (probabilistic or deterministic) mechanism that guarantees an ex post efficient outcome must fail even a weak form of strategyproofness.
Decoding the Text Encoding
Venue: arXiv cs.HC 2014
Year: 2014

Word clouds and text visualization is one of the recent most popular and widely used types of visualizations. Despite the attractiveness and simplicity of producing word clouds, they do not provide a thorough visualization for the distribution of the underlying data. Therefore, it is important to redesign word clouds for improving their design choices and to be able to do further statistical analysis on data. In this paper we have proposed a fully automatic redesigning algorithm for word cloud visualization. Our proposed method is able to decode an input word cloud visualization and provides the raw data in the form of a list of (word, value) pairs. To the best of our knowledge our work is the first attempt to extract raw data from word cloud visualization. We have tested our proposed method both qualitatively and quantitatively. The results of our experiments show that our algorithm is able to extract the words and their weights effectively with considerable low error rate.
On Symmetrized Weight Compositions
Venue: arXiv cs.IT 2014
Year: 2014

A characterization of module alphabets with the Hamming weight EP (abbreviation for Extension Property) had been settled. A thoughtfully constructed example by J.A.Wood finished the tour. Frobenius bimodules were proved to satisfy the EP with respect to symmetrized weight compositions. In 4, the embeddability in the character group of the ambient ring R was found sufficient for a module RA to satisfy the EP with respect to swc built on any subgroup of AutR(A), while the necessity remained a question. A least action trial suggests bridging to the already settled case, a trial that turns out to be successful. Here, landing in a Midway, the necessity is proved by jumping to Hamming weight. Corollary 1.11 declares a characterization of module alphabets satisfying the EP with respect to swc
Matrix Coherency Graph: A Tool for Improving Sparse Coding Performance
Venue: arXiv cs.IT 2014
Year: 2014

Exact recovery of a sparse solution for an underdetermined system of linear equations implies full search among all possible subsets of the dictionary, which is computationally intractable, while l1 minimization will do the job when a Restricted Isometry Property holds for the dictionary. Yet, practical sparse recovery algorithms may fail to recover the vector of coefficients even when the dictionary deviates from the RIP only slightly. To enjoy l1 minimization guarantees in a wider sense, a method based on a combination of full-search and l1 minimization is presented. The idea is based on partitioning the dictionary into atoms which are in some sense well-conditioned and those which are ill-conditioned. Inspired by that, a matrix coherency graph is introduced which is a tool extracted by the structure of the dictionary. This tool can be used for decreasing the greediness of sparse coding algorithms so that recovery will be more reliable. We have modified the IRLS algorithm by applying the proposed method on it and simulation results show that the modified version performs quite better than the original algorithm.
Strongly Separable Codes
Venue: arXiv cs.IT 2014
Year: 2014

Binary $t$-frameproof codes ($t$-FPCs) are used in multimedia fingerprinting schemes where the identification of authorized users taking part in the averaging collusion attack is required. In this paper, a binary strongly $\bar{t}$-separable code ($\bar{t}$-SSC) is introduced to improve such a scheme based on a binary $t$-FPC. A binary $\bar{t}$-SSC has the same traceability as a binary $t$-FPC but has more codewords than a binary $t$-FPC. A composition construction for binary $\bar{t}$-SSCs from $q$-ary $\bar{t}$-SSCs is described, which stimulates the research on $q$-ary $\bar{t}$-SSCs with short length. Several infinite series of optimal $q$-ary $\bar{2}$-SSCs of length $2$ are derived from the fact that a $q$-ary $\bar{2}$-SSC of length $2$ is equivalent to a $q$-ary $\bar{2}$-separable code of length $2$. Combinatorial properties of $q$-ary $\bar{2}$-SSCs of length $3$ are investigated, and a construction for $q$-ary $\bar{2}$-SSCs of length $3$ is provided. These $\bar{2}$-SSCs of length $3$ have more than $12.5\%$ codewords than $2$-FPCs of length $3$ could have.
Block Based Medical Image Watermarking Technique for Tamper Detection and Recovery
Venue: arXiv cs.MM 2014
Year: 2014

In this paper, we propose a novel fragile block based medical image watermarking technique for embedding data of patient into medical image, verifying the integrity of ROI (Region of Interest), detecting the tampered blocks inside ROI and recovering original ROI with less size authentication and recovery data and with simple mathematical calculations. In the proposed method, the medical image is divided into three regions called ROI, RONI (Region of Non Interest) and border pixels. Later, authentication data of ROI and Electronic Patient Record (EPR) are compressed using Run Length Encoding (RLE) technique and then embedded into ROI. Recovery information of ROI is embedded inside RONI and information of ROI is embedded inside border pixels. Results of experiments conducted on several medical images reveal that proposed method produces high quality watermarked medical images, identifies tampered areas inside ROI of watermarked medical images and recovers the original ROI.
Maximizing algebraic connectivity for certain families of graphs
Venue: arXiv cs.DM 2014
Year: 2014

We investigate the bounds on algebraic connectivity of graphs subject to constraints on the number of edges, vertices, and topology. We show that the algebraic connectivity for any tree on $n$ vertices and with maximum degree $d$ is bounded above by $2(d-2) \frac{1}{n}+O(\frac{\ln n}{n^{2}}) .$ We then investigate upper bounds on algebraic connectivity for cubic graphs. We show that algebraic connectivity of a cubic graph of girth $g$ is bounded above by $3-2^{3/2}\cos(π/\lfloor g/2\rfloor) ,$ which is an improvement over the bound found by Nilli [A. Nilli, Electron. J. Combin., 11(9), 2004]. Finally, we propose several conjectures and open questions.