OpenRaiser/Intern-Atlas huggingface dataset:
Anti-patterns and the energy efficiency of Android applications
Venue: arXiv cs.SE 2016
Year: 2016

The boom in mobile apps has changed the traditional landscape of software development by introducing new challenges due to the limited resources of mobile devices, e.g., memory, CPU, network bandwidth and battery. The energy consumption of mobile apps is nowadays a hot topic and researchers are actively investigating the role of coding practices on energy efficiency. Recent studies suggest that design quality can conflict with energy efficiency. Therefore, it is important to take into account energy efficiency when evolving the design of a mobile app. The research community has proposed approaches to detect and remove anti-patterns (i.e., poor solutions to design and implementation problems) in software systems but, to the best of our knowledge, none of these approaches have included anti-patterns that are specific to mobile apps and--or considered the energy efficiency of apps. In this paper, we fill this gap in the literature by analyzing the impact of eight type of anti-patterns on a testbed of 59 android apps extracted from F-Droid. First, we (1) analyze the impact of anti-patterns in mobile apps with respect to energy efficiency; then (2) we study the impact of different types of anti-patterns on energy efficiency. We found that then energy consumption of apps containing anti-patterns and not (refactored apps) is statistically different. Moreover, we find that the impact of refactoring anti-patterns can be positive (7 type of anti-patterns) or negative (2 type of anti-patterns). Therefore, developers should consider the impact on energy efficiency of refactoring when applying maintenance activities.
Finding Representative Points in Multivariate Data Using PCA
Venue: arXiv cs.IR 2016
Year: 2016

The idea of representation has been used in various fields of study from data analysis to political science. In this paper, we define representativeness and describe a method to isolate data points that can represent the entire data set. Also, we show how the minimum set of representative data points can be generated. We use data from GLOBE (a project to study the effects on Land Change based on a set of parameters that include temperature, forest cover, human population, atmospheric parameters and many other variables) to test & validate the algorithm. Principal Component Analysis (PCA) is used to reduce the dimensions of the multivariate data set, so that the representative points can be generated efficiently and its Representativeness has been compared against Random Sampling of points from the data set.
CuMF_SGD: Fast and Scalable Matrix Factorization
Venue: arXiv cs.LG 2016
Year: 2016

Matrix factorization (MF) has been widely used in e.g., recommender systems, topic modeling and word embedding. Stochastic gradient descent (SGD) is popular in solving MF problems because it can deal with large data sets and is easy to do incremental learning. We observed that SGD for MF is memory bound. Meanwhile, single-node CPU systems with caching performs well only for small data sets; distributed systems have higher aggregated memory bandwidth but suffer from relatively slow network connection. This observation inspires us to accelerate MF by utilizing GPUs's high memory bandwidth and fast intra-node connection. We present cuMF_SGD, a CUDA-based SGD solution for large-scale MF problems. On a single CPU, we design two workload schedule schemes, i.e., batch-Hogwild! and wavefront-update that fully exploit the massive amount of cores. Especially, batch-Hogwild! as a vectorized version of Hogwild! overcomes the issue of memory discontinuity. We also develop highly-optimized kernels for SGD update, leveraging cache, warp-shuffle instructions and half-precision floats. We also design a partition scheme to utilize multiple GPUs while addressing the well-known convergence issue when parallelizing SGD. On three data sets with only one Maxwell or Pascal GPU, cuMF_SGD runs 3.1X-28.2X as fast compared with state-of-art CPU solutions on 1-64 CPU nodes. Evaluations also show that cuMF_SGD scales well on multiple GPUs in large data sets.
An automatic bad band preremoval algorithm for hyperspectral imagery
Venue: arXiv cs.CV 2016
Year: 2016

For most hyperspectral remote sensing applications, removing bad bands, such as water absorption bands, is a required preprocessing step. Currently, the commonly applied method is by visual inspection, which is very time-consuming and it is easy to overlook some noisy bands. In this study, we find an inherent connection between target detection algorithms and the corrupted band removal. As an example, for the matched filter (MF), which is the most widely used target detection method for hyperspectral data, we present an automatic MF-based algorithm for bad band identification. The MF detector is a filter vector, and the resulting filter output is the sum of all bands weighted by the MF coefficients. Therefore, we can identify bad bands only by using the MF filter vector itself, the absolute value of whose entry accounts for the importance of each band for the target detection. For a specific target of interest, the bands with small MF weights correspond to the noisy or bad ones. Based on this fact, we develop an automatic bad band preremoval algorithm by utilizing the average absolute value of MF weights for multiple targets within a scene. Experiments with three well known hyperspectral datasets show that our method can always identify the water absorption and other low signal-to-noise (SNR) bands that are usually chosen as bad bands manually.
An algorithmic approach using multivariate polynomials for the nonlinearity of Boolean functions
Venue: arXiv cs.IT 2016
Year: 2016

The nonlinearity of a Boolean function is a key property in deciding its suitability for cryptographic purposes, e.g. as a combining function in stream ciphers, and so the nonlinearity computation is an important problem for applications. Traditional methods to compute the nonlinearity are based on transforms, such as the Fast Walsh Transform. In 2007 Simonetti proposed a method to solve the above problem seen as a decision problem on the existence of solutions for some multivariate polynomial systems. Although novel as approach, her algorithm suffered from a direct application of Groebner bases and was thus impractical. We now propose two more practical approaches, one that determines the existence of solutions for Simonetti's systems in a faster way and another that writes similar systems but over fields with a different characteristics. For our algorithms we provide an efficient implementation in the software package MAGMA.
A multi-task learning model for malware classification with useful file access pattern from API call sequence
Venue: arXiv cs.SD 2016
Year: 2016

Based on API call sequences, semantic-aware and machine learning (ML) based malware classifiers can be built for malware detection or classification. Previous works concentrate on crafting and extracting various features from malware binaries, disassembled binaries or API calls via static or dynamic analysis and resorting to ML to build classifiers. However, they tend to involve too much feature engineering and fail to provide interpretability. We solve these two problems with the recent advances in deep learning: 1) RNN-based autoencoders (RNN-AEs) can automatically learn low-dimensional representation of a malware from its raw API call sequence. 2) Multiple decoders can be trained under different supervisions to give more information, other than the class or family label of a malware. Inspired by the works of document classification and automatic sentence summarization, each API call sequence can be regarded as a sentence. In this paper, we make the first attempt to build a multi-task malware learning model based on API call sequences. The model consists of two decoders, one for malware classification and one for $\emph{file access pattern}$ (FAP) generation given the API call sequence of a malware. We base our model on the general seq2seq framework. Experiments show that our model can give competitive classification results as well as insightful FAP information.
Unfolding Semantics of the Untyped λ-Calculus with letrec
Venue: arXiv cs.PL 2016
Year: 2016

We investigate the relationship between finite terms in λ-letrec, the λ-calculus with letrec, and the infinite λ-terms they express. We say that a lambda-letrec term expresses a lambda-term if the latter can be obtained as an infinite unfolding of the former. Unfolding is the process of substituting occurrences of function variables by the right-hand side of their definition. We consider the following questions: (i) How can we characterise those infinite λ-terms that are λ-letrec-expressible? (ii) Given two λ-letrec terms, how can we determine whether they have the same unfolding? (iii) Given a λ-letrec term, can we find a more compact version of the term with the same unfolding? To tackle these questions we introduce and study the following formalisms: (i) a rewriting system for unfolding λ-letrec terms into λ-terms (ii) a rewriting system for `observing' λ-terms by dissecting their term structure (iii) higher-order and first-order graph formalisms together with translations between them as well as translations from and to λ-letrec. We identify a first-order term graph formalism on which bisimulation preserves and reflects the unfolding semantics of λ-letrec and which is closed under functional bisimulation. From this we derive efficient methods to determine whether two terms are equivalent under infinite unfolding and to compute the maximally shared form of a given λ-letrec term.
Constrained Cohort Intelligence using Static and Dynamic Penalty Function Approach for Mechanical Components Design
Venue: arXiv cs.AI 2016
Year: 2016

Most of the metaheuristics can efficiently solve unconstrained problems; however, their performance may degenerate if the constraints are involved. This paper proposes two constraint handling approaches for an emerging metaheuristic of Cohort Intelligence (CI). More specifically CI with static penalty function approach (SCI) and CI with dynamic penalty function approach (DCI) are proposed. The approaches have been tested by solving several constrained test problems. The performance of the SCI and DCI have been compared with algorithms like GA, PSO, ABC, d-Ds. In addition, as well as three real world problems from mechanical engineering domain with improved solutions. The results were satisfactory and validated the applicability of CI methodology for solving real world problems.
ERMrest: an entity-relationship data storage service for web-based, data-oriented collaboration
Venue: arXiv cs.DB 2016
Year: 2016

Scientific discovery is increasingly dependent on a scientist's ability to acquire, curate, integrate, analyze, and share large and diverse collections of data. While the details vary from domain to domain, these data often consist of diverse digital assets (e.g. image files, sequence data, or simulation outputs) that are organized with complex relationships and context which may evolve over the course of an investigation. In addition, discovery is often collaborative, such that sharing of the data and its organizational context is highly desirable. Common systems for managing file or asset metadata hide their inherent relational structures, while traditional relational database systems do not extend to the distributed collaborative environment often seen in scientific investigations. To address these issues, we introduce ERMrest, a collaborative data management service which allows general entity-relationship modeling of metadata manipulated by RESTful access methods. We present the design criteria, architecture, and service implementation, as well as describe an ecosystem of tools and services that we have created to integrate metadata into an end-to-end scientific data life cycle. ERMrest has been deployed to hundreds of users across multiple scientific research communities and projects. We present two representative use cases: an international consortium and an early-phase, multidisciplinary research project.
K-Nearest Neighbor Classification Using Anatomized Data
Venue: arXiv cs.LG 2016
Year: 2016

This paper analyzes k nearest neighbor classification with training data anonymized using anatomy. Anatomy preserves all data values, but introduces uncertainty in the mapping between identifying and sensitive values. We first study the theoretical effect of the anatomized training data on the k nearest neighbor error rate bounds, nearest neighbor convergence rate, and Bayesian error. We then validate the derived bounds empirically. We show that 1) Learning from anatomized data approaches the limits of learning through the unprotected data (although requiring larger training data), and 2) nearest neighbor using anatomized data outperforms nearest neighbor on generalization-based anonymization.
Multilevel Anomaly Detection for Mixed Data
Venue: arXiv cs.LG 2016
Year: 2016

Anomalies are those deviating from the norm. Unsupervised anomaly detection often translates to identifying low density regions. Major problems arise when data is high-dimensional and mixed of discrete and continuous attributes. We propose MIXMAD, which stands for MIXed data Multilevel Anomaly Detection, an ensemble method that estimates the sparse regions across multiple levels of abstraction of mixed data. The hypothesis is for domains where multiple data abstractions exist, a data point may be anomalous with respect to the raw representation or more abstract representations. To this end, our method sequentially constructs an ensemble of Deep Belief Nets (DBNs) with varying depths. Each DBN is an energy-based detector at a predefined abstraction level. At the bottom level of each DBN, there is a Mixed-variate Restricted Boltzmann Machine that models the density of mixed data. Predictions across the ensemble are finally combined via rank aggregation. The proposed MIXMAD is evaluated on high-dimensional realworld datasets of different characteristics. The results demonstrate that for anomaly detection, (a) multilevel abstraction of high-dimensional and mixed data is a sensible strategy, and (b) empirically, MIXMAD is superior to popular unsupervised detection methods for both homogeneous and mixed data.
A Growing Long-term Episodic & Semantic Memory
Venue: arXiv cs.AI 2016
Year: 2016

The long-term memory of most connectionist systems lies entirely in the weights of the system. Since the number of weights is typically fixed, this bounds the total amount of knowledge that can be learned and stored. Though this is not normally a problem for a neural network designed for a specific task, such a bound is undesirable for a system that continually learns over an open range of domains. To address this, we describe a lifelong learning system that leverages a fast, though non-differentiable, content-addressable memory which can be exploited to encode both a long history of sequential episodic knowledge and semantic knowledge over many episodes for an unbounded number of domains. This opens the door for investigation into transfer learning, and leveraging prior knowledge that has been learned over a lifetime of experiences to new domains.
Utilization of Deep Reinforcement Learning for saccadic-based object visual search
Venue: arXiv cs.CV 2016
Year: 2016

The paper focuses on the problem of learning saccades enabling visual object search. The developed system combines reinforcement learning with a neural network for learning to predict the possible outcomes of its actions. We validated the solution in three types of environment consisting of (pseudo)-randomly generated matrices of digits. The experimental verification is followed by the discussion regarding elements required by systems mimicking the fovea movement and possible further research directions.
Lexicons and Minimum Risk Training for Neural Machine Translation: NAIST-CMU at WAT2016
Venue: arXiv cs.CL 2016
Year: 2016

This year, the Nara Institute of Science and Technology (NAIST)/Carnegie Mellon University (CMU) submission to the Japanese-English translation track of the 2016 Workshop on Asian Translation was based on attentional neural machine translation (NMT) models. In addition to the standard NMT model, we make a number of improvements, most notably the use of discrete translation lexicons to improve probability estimates, and the use of minimum risk training to optimize the MT system for BLEU score. As a result, our system achieved the highest translation evaluation scores for the task.
Fine-grained Recognition in the Noisy Wild: Sensitivity Analysis of Convolutional Neural Networks Approaches
Venue: arXiv cs.CV 2016
Year: 2016

In this paper, we study the sensitivity of CNN outputs with respect to image transformations and noise in the area of fine-grained recognition. In particular, we answer the following questions (1) how sensitive are CNNs with respect to image transformations encountered during wild image capture?; (2) how can we predict CNN sensitivity?; and (3) can we increase the robustness of CNNs with respect to image degradations? To answer the first question, we provide an extensive empirical sensitivity analysis of commonly used CNN architectures (AlexNet, VGG19, GoogleNet) across various types of image degradations. This allows for predicting CNN performance for new domains comprised by images of lower quality or captured from a different viewpoint. We also show how the sensitivity of CNN outputs can be predicted for single images. Furthermore, we demonstrate that input layer dropout or pre-filtering during test time only reduces CNN sensitivity for high levels of degradation. Experiments for fine-grained recognition tasks reveal that VGG19 is more robust to severe image degradations than AlexNet and GoogleNet. However, small intensity noise can lead to dramatic changes in CNN performance even for VGG19.
Robust training on approximated minimal-entropy set
Venue: arXiv cs.LG 2016
Year: 2016

In this paper, we propose a general framework to learn a robust large-margin binary classifier when corrupt measurements, called anomalies, caused by sensor failure might be present in the training set. The goal is to minimize the generalization error of the classifier on non-corrupted measurements while controlling the false alarm rate associated with anomalous samples. By incorporating a non-parametric regularizer based on an empirical entropy estimator, we propose a Geometric-Entropy-Minimization regularized Maximum Entropy Discrimination (GEM-MED) method to learn to classify and detect anomalies in a joint manner. We demonstrate using simulated data and a real multimodal data set. Our GEM-MED method can yield improved performance over previous robust classification methods in terms of both classification accuracy and anomaly detection rate.
The Anatomy of Brexit Debate on Facebook
Venue: arXiv cs.SI 2016
Year: 2016

Nowadays users get informed and shape their opinion through social media. However, the disintermediated access to contents does not guarantee quality of information. Selective exposure and confirmation bias, indeed, have been shown to play a pivotal role in content consumption and information spreading. Users tend to select information adhering (and reinforcing) their worldview and to ignore dissenting information. This pattern elicits the formation of polarized groups -- i.e., echo chambers -- where the interaction with like-minded people might even reinforce polarization. In this work we address news consumption around Brexit in UK on Facebook. In particular, we perform a massive analysis on more than 1 Million users interacting with Brexit related posts from the main news providers between January and July 2016. We show that consumption patterns elicit the emergence of two distinct communities of news outlets. Furthermore, to better characterize inner group dynamics, we introduce a new technique which combines automatic topic extraction and sentiment analysis. We compare how the same topics are presented on posts and the related emotional response on comments finding significant differences in both echo chambers and that polarization influences the perception of topics. Our results provide important insights about the determinants of polarization and evolution of core narratives on online debating.
Learning to Protect Communications with Adversarial Neural Cryptography
Venue: arXiv cs.CR 2016
Year: 2016

We ask whether neural networks can learn to use secret keys to protect information from other neural networks. Specifically, we focus on ensuring confidentiality properties in a multiagent system, and we specify those properties in terms of an adversary. Thus, a system may consist of neural networks named Alice and Bob, and we aim to limit what a third neural network named Eve learns from eavesdropping on the communication between Alice and Bob. We do not prescribe specific cryptographic algorithms to these neural networks; instead, we train end-to-end, adversarially. We demonstrate that the neural networks can learn how to perform forms of encryption and decryption, and also how to apply these operations selectively in order to meet confidentiality goals.
Bit-pragmatic Deep Neural Network Computing
Venue: arXiv cs.LG 2016
Year: 2016

We quantify a source of ineffectual computations when processing the multiplications of the convolutional layers in Deep Neural Networks (DNNs) and propose Pragmatic (PRA), an architecture that exploits it improving performance and energy efficiency. The source of these ineffectual computations is best understood in the context of conventional multipliers which generate internally multiple terms, that is, products of the multiplicand and powers of two, which added together produce the final product [1]. At runtime, many of these terms are zero as they are generated when the multiplicand is combined with the zero-bits of the multiplicator. While conventional bit-parallel multipliers calculate all terms in parallel to reduce individual product latency, PRA calculates only the non-zero terms using a) on-the-fly conversion of the multiplicator representation into an explicit list of powers of two, and b) hybrid bit-parallel multplicand/bit-serial multiplicator processing units. PRA exploits two sources of ineffectual computations: 1) the aforementioned zero product terms which are the result of the lack of explicitness in the multiplicator representation, and 2) the excess in the representation precision used for both multiplicants and multiplicators, e.g., [2]. Measurements demonstrate that for the convolutional layers, a straightforward variant of PRA improves performance by 2.6x over the DaDiaNao (DaDN) accelerator [3] and by 1.4x over STR [4]. Similarly, PRA improves energy efficiency by 28% and 10% on average compared to DaDN and STR. An improved cross lane synchronication scheme boosts performance improvements to 3.1x over DaDN. Finally, Pragmatic benefits persist even with an 8-bit quantized representation [5].
Attack Analysis Results for Adversarial Engagement 1 of the DARPA Transparent Computing Program
Venue: arXiv cs.CR 2016
Year: 2016

This report presents attack analysis results of the first adversarial engagement event stream for the first engagement of the DARPA TC program conducted in October 2016. The analysis was performed by Stony Brook University and University of Illinois at Chicago. The findings in this report are obtained without prior knowledge of the attacks conducted.