pwc-archive/papers-with-abstracts huggingface dataset:
Deviation inequalities for stochastic approximation by averaging
Authors: Xiequan Fan, Pierre Alquier, Paul Doukhan
Date: 2021-02-17 00:00:00

We introduce a class of Markov chains, that contains the model of stochastic approximation by averaging and non-averaging. Using martingale approximation method, we establish various deviation inequalities for separately Lipschitz functions of such a chain, with different moment conditions on some dominating random variables of martingale differences.Finally, we apply these inequalities to the stochastic approximation by averaging and empirical risk minimisation.
Finding the Gap: Neuromorphic Motion Vision in Cluttered Environments
Authors: Thorben Schoepe, Ella Janotte, Moritz B. Milde, Olivier J. N. Bertrand, Martin Egelhaaf, Elisabetta Chicca
Date: 2021-02-16 00:00:00
Tasks: Autonomous Vehicles, Collision Avoidance, Decision Making

Many animals meander in environments and avoid collisions. How the underlying neuronal machinery can yield robust behaviour in a variety of environments remains unclear. In the fly brain, motion-sensitive neurons indicate the presence of nearby objects and directional cues are integrated within an area known as the central complex. Such neuronal machinery, in contrast with the traditional stream-based approach to signal processing, uses an event-based approach, with events occurring when changes are sensed by the animal. Contrary to von Neumann computing architectures, event-based neuromorphic hardware is designed to process information in an asynchronous and distributed manner. Inspired by the fly brain, we model, for the first time, a neuromorphic closed-loop system mimicking essential behaviours observed in flying insects, such as meandering in clutter and gap crossing, which are highly relevant for autonomous vehicles. We implemented our system both in software and on neuromorphic hardware. While moving through an environment, our agent perceives changes in its surroundings and uses this information for collision avoidance. The agent's manoeuvres result from a closed action-perception loop implementing probabilistic decision-making processes. This loop-closure is thought to have driven the development of neural circuitry in biological agents since the Cambrian explosion. In the fundamental quest to understand neural computation in artificial agents, we come closer to understanding and modelling biological intelligence by closing the loop also in neuromorphic systems. As a closed-loop system, our system deepens our understanding of processing in neural networks and computations in biological and artificial systems. With these investigations, we aim to set the foundations for neuromorphic intelligence in the future, moving towards leveraging the full potential of neuromorphic systems.
Neuroevolution in Deep Learning: The Role of Neutrality
Authors: Edgar Galván
Date: 2021-02-16 00:00:00
Tasks: Deep Learning, Evolutionary Algorithms

A variety of methods have been applied to the architectural configuration and learning or training of artificial deep neural networks (DNN). These methods play a crucial role in the success or failure of the DNN for most problems and applications. Evolutionary Algorithms (EAs) are gaining momentum as a computationally feasible method for the automated optimisation of DNNs. Neuroevolution is a term which describes these processes of automated configuration and training of DNNs using EAs. However, the automatic design and/or training of these modern neural networks through evolutionary algorithms is computanalli expensive. Kimura's neutral theory of molecular evolution states that the majority of evolutionary changes at molecular level are the result of random fixation of selectively neutral mutations. A mutation from one gene to another is neutral if it does not affect the phenotype. This work discusses how neutrality, given certain conditions, can help to speed up the training/design of deep neural networks.
An Implementation of Vector Quantization using the Genetic Algorithm Approach
Authors: Maha Mohammed Khan
Date: 2021-02-16 00:00:00
Tasks: Articles, BIG-bench Machine Learning, Image Compression, Quantization

The application of machine learning(ML) and genetic programming(GP) to the image compression domain has produced promising results in many cases. The need for compression arises due to the exorbitant size of data shared on the internet. Compression is required for text, videos, or images, which are used almost everywhere on web be it news articles, social media posts, blogs, educational platforms, medical domain, government services, and many other websites, need packets for transmission and hence compression is necessary to avoid overwhelming the network. This paper discusses some of the implementations of image compression algorithms that use techniques such as Artificial Neural Networks, Residual Learning, Fuzzy Neural Networks, Convolutional Neural Nets, Deep Learning, Genetic Algorithms. The paper also describes an implementation of Vector Quantization using GA to generate codebook which is used for Lossy image compression. All these approaches prove to be very contrasting to the standard approaches to processing images due to the highly parallel and computationally extensive nature of machine learning algorithms. Such non-linear abilities of ML and GP make it widely popular for use in multiple domains. Traditional approaches are also combined with artificially intelligent systems, leading to hybrid systems, to achieve better results.
Sound event detection in domestic environments withweakly labeled data and soundscape synthesis
Authors: Nicolas Turpault, Romain Serizel, Ankit Shah, Justin Salamon
Date: 2019-10-26 00:00:00
Tasks: Event Detection, Sound Event Detection

This paper presents Task 4 of the Detection and Classification of Acoustic  Scenes  and  Events  (DCASE)  2019  challenge  and  provides a first analysis of the challenge results.  The task is a follow-up  to  Task  4  of  DCASE  2018,  and  involves  training  systems for  large-scale  detection  of  sound  events  using  a  combination  of weakly  labeled  data,  i.e.  training  labels  without  time  boundaries,and strongly-labeled synthesized data.   The paper introduces Domestic Environment Sound Event Detection (DESED) dataset mixing a part of last year dataset and an additional synthetic, strongly labeled, dataset provided this year that we’ll describe more in de-tail.  We also report the performance of the submitted systems on the official evaluation (test) and development sets as well as several additional datasets. The best systems from this year outperform last year’s winning system by about 10% points in terms of F-measure.
Numerical Approximation of the Implied Volatility Under Arithmetic Brownian Motion
Authors: Jaehyuk Choi, Kwangmoon Kim, Minsuk Kwak
Date: 2009-06-29 00:00:00

We provide an accurate approximation method for inverting an option price to the implied volatility under arithmetic Brownian motion, which is widely quoted in Fixed Income markets. The maximum error in the volatility is in the order of 10−10 of the given option price and much smaller for the near-the-money options. Thus our approximation can be used as an exact solution without further refinements of iterative methods.
Word Sense Disambiguation: A comprehensive knowledge exploitation framework
Authors: Yinglin Wang, Ming Wang, Hamido Fujita
Date: 2020-02-29 00:00:00
Tasks: graph construction, Information Retrieval, Machine Translation, Retrieval, Sentence, Sentiment Analysis, Translation, Word Sense Disambiguation

Word Sense Disambiguation (WSD) has been a basic and on-going issue since its introduction in natural language processing (NLP) community. Its application lies in many different areas including sentiment analysis, Information Retrieval (IR), machine translation and knowledge graph construction. Solutions to WSD are mostly categorized into supervised and knowledge-based approaches. In this paper, a knowledge-based method is proposed, modeling the problem with semantic space and semantic path hidden behind a given sentence. The approach relies on the well-known Knowledge Base (KB) named WordNet and models the semantic space and semantic path by Latent Semantic Analysis (LSA) and PageRank respectively. Experiments has proven the method’s effectiveness, achieving state-of-the-art performance in several WSD datasets.
Improving Question Classification by Feature Extraction and Selection
Authors: Nguyen Van-Tu, Le Anh-Cuong
Date: 2016-01-01 00:00:00
Tasks: Classification, feature selection, General Classification, Question Answering, Sentence, Text Classification

Question classification is the task of predicting the entity type of the answering sentence for a given question in natural language. It plays an important role in finding or constructing accurate answers and therefore helps to improve quality of automated question answering systems. Different lexical, syntactical and semantic features was extracted automatically from a question to serve the classification in previous studies. However, combining all those features doesn’t always give the best results for all types of questions. Different from previous studies, this paper focuses on the problem of how to extract and select efficient features adapting to each different types of question. We first propose a method of using a feature selection algorithm to determine appropriate features corresponding to different question types. Secondly, we design a new type of features, which is based on question patterns. We tested our proposed approach on the benchmark dataset TREC and using Support Vector Machines (SVM) for the classification algorithm. The experiment shows obtained results with the accuracies of 95.2% and 91.6% for coarse grain and fine grain data sets respectively, which are much better in comparison with the previous studies.
A Burstiness-aware Approach for Document Dating
Authors: Dimitrios Kotsakos, Theodoros  Lappas, Dimitrios  Kotzias, Dimitrios Gunopulos, Nattiya Kanhabua, Kjetil Nørvåg
Date: 2014-07-01 00:00:00
Tasks: Document Dating, Event Detection

A large number of mainstream applications, like temporal search, event detection, and trend identification, assume knowledge of the timestamp of every document in a given textual collection. In many cases, however, the required timestamps are either unavailable or ambiguous. A characteristic instance of this problem emerges in the context of large repositories of old digitized documents. For such documents, the timestamp may be corrupted during the digitization process, or may simply be unavailable. In this paper, we study the task of approximating the timestamp of a document, so-called document dating. We propose a contentbased method and use recent advances in the domain of term burstiness, which allow it to overcome the drawbacks of previous document dating methods, e.g. the fix time partition strategy. We use an extensive experimental evaluation on different datasets to validate the efficacy and advantages of our methodology, showing that our method outperforms the state of the art methods on document dating.
Placing Grid-Forming Converters to Enhance Small Signal Stability of PLL-Integrated Power Systems
Authors: Chaoran Yang, Linbin Huang, Huanhai Xin, Ping Ju
Date: 2020-07-08 00:00:00

The modern power grid features the high penetration of power converters, which widely employ a phase-locked loop (PLL) for grid synchronization. However, it has been pointed out that PLL can give rise to small-signal instabilities under weak grid conditions. This problem can be potentially resolved by operating the converters in grid-forming mode, namely, without using a PLL. Nonetheless, it has not been theoretically revealed how the placement of grid-forming converters enhances the small-signal stability of power systems integrated with large-scale PLL-based converters. This paper aims at filling this gap. Based on matrix perturbation theory, we explicitly demonstrate that the placement of grid-forming converters is equivalent to increasing the power grid strength and thus improving the small-signal stability of PLL-based converters. Furthermore, we investigate the optimal locations to place grid-forming converters by increasing the smallest eigenvalue of the weighted and Kron-reduced Laplacian matrix of the power network. The analysis in this paper is validated through high-fidelity simulation studies on a modified two-area test system and a modified 39-bus test system. This paper potentially lays the foundation for understanding the interaction between PLL-based (i.e., grid-following) converters and grid-forming converters, and coordinating their placements in future converter-dominated power systems.
A near analytic solution of a stochastic immune response model considering variability in virus and T cell dynamics
Authors: Abhilasha Batra, Rati Sharma
Date: 2021-02-17 00:00:00

Biological processes at the cellular level are stochastic in nature, and the immune response system is no different. Therefore, models that attempt to explain this system need to also incorporate noise or fluctuations that can account for the observed variability. In this work, a stochastic model of the immune response system is presented in terms of the dynamics of the T cells and the virus particles. Making use of the Green's function and the Wilemski-Fixman approximation, this model is then solved to obtain the analytical expression for the joint probability density function of these variables in the early and late stages of infection. This is then also used to calculate the average level of virus particles in the system. Upon comparing the theoretically predicted average virus levels to those of COVID-19 patients, it is hypothesized that the long lived dynamics that are characteristic of such viral infections are due to the long range correlations in the temporal fluctuations of the virions. This model therefore provides an insight into the effects of noise on viral dynamics.
Comparative Analysis of Methods for Cloud Segmentation in Ground-Based Infrared Images
Authors: Guillermo Terrén-Serrano, Manel Martínez-Ramón
Date: 2020-12-13 00:00:00
Tasks: Segmentation, Solar Irradiance Forecasting

The increasing penetration of photovoltaic systems in the power grid makes it vulnerable to cloud shadow projection. Real-time cloud segmentation in ground-based infrared images is important to reduce the noise in intra-hour global solar irradiance forecasting. We present a comparison between discriminative and generative models for cloud segmentation. The performances of supervised and unsupervised learning methods in cloud segmentation are evaluated. The discriminative models are solved in the primal formulation to make them feasible in real-time applications. The performances are compared using the j-statistic. Infrared image preprocessing to remove stationary artifacts increases the overall performance in the analyzed methods. The inclusion of features from neighboring pixels in the feature vectors leads to a performance improvement in some of the cases. Markov Random Fields achieve the best performance in both unsupervised and supervised generative models. Discriminative models solved in the primal yield a dramatically lower computing time along with high performance in the segmentation. Generative and discriminative models are comparable when preprocessing is applied to the infrared images.
Deep Learning for Suicide and Depression Identification with Unsupervised Label Correction
Authors: Ayaan Haque, Viraaj Reddi, Tyler Giallanza
Date: 2021-02-18 00:00:00
Tasks: Deep Learning

Early detection of suicidal ideation in depressed individuals can allow for adequate medical attention and support, which in many cases is life-saving. Recent NLP research focuses on classifying, from a given piece of text, if an individual is suicidal or clinically healthy. However, there have been no major attempts to differentiate between depression and suicidal ideation, which is an important clinical challenge. Due to the scarce availability of EHR data, suicide notes, or other similar verified sources, web query data has emerged as a promising alternative. Online sources, such as Reddit, allow for anonymity that prompts honest disclosure of symptoms, making it a plausible source even in a clinical setting. However, these online datasets also result in lower performance, which can be attributed to the inherent noise in web-scraped labels, which necessitates a noise-removal process. Thus, we propose SDCNL, a suicide versus depression classification method through a deep learning approach. We utilize online content from Reddit to train our algorithm, and to verify and correct noisy labels, we propose a novel unsupervised label correction method which, unlike previous work, does not require prior noise distribution information. Our extensive experimentation with multiple deep word embedding models and classifiers display the strong performance of the method in anew, challenging classification application. We make our code and dataset available at https://github.com/ayaanzhaque/SDCNL
DeeperForensics Challenge 2020 on Real-World Face Forgery Detection: Methods and Results
Authors: Liming Jiang, Zhengkui Guo, Wayne Wu, Zhaoyang Liu, Ziwei Liu, Chen Change Loy, Shuo Yang, Yuanjun Xiong, Wei Xia, Baoying Chen, Peiyu Zhuang, Sili Li, Shen Chen, Taiping Yao, Shouhong Ding, Jilin Li, Feiyue Huang, Liujuan Cao, Rongrong Ji, Changlei Lu, Ganchao Tan
Date: 2021-02-18 00:00:00
Tasks: valid

This paper reports methods and results in the DeeperForensics Challenge 2020 on real-world face forgery detection. The challenge employs the DeeperForensics-1.0 dataset, one of the most extensive publicly available real-world face forgery detection datasets, with 60,000 videos constituted by a total of 17.6 million frames. The model evaluation is conducted online on a high-quality hidden test set with multiple sources and diverse distortions. A total of 115 participants registered for the competition, and 25 teams made valid submissions. We will summarize the winning solutions and present some discussions on potential research directions.
Understanding algorithmic collusion with experience replay
Authors: Bingyan Han
Date: 2021-02-18 00:00:00
Tasks: Q-Learning

In an infinitely repeated pricing game, pricing algorithms based on artificial intelligence (Q-learning) may consistently learn to charge supra-competitive prices even without communication. Although concerns on algorithmic collusion have arisen, little is known on underlying factors. In this work, we experimentally analyze the dynamics of algorithms with three variants of experience replay. Algorithmic collusion still has roots in human preferences. Randomizing experience yields prices close to the static Bertrand equilibrium and higher prices are easily restored by favoring the latest experience. Moreover, relative performance concerns also stabilize the collusion. Finally, we investigate the scenarios with heterogeneous agents and test robustness on various factors.
The Likelihood of Mixed Hitting Times
Authors: Jaap H. Abbring, Tim Salimans
Date: 2019-05-09 00:00:00

We present a method for computing the likelihood of a mixed hitting-time model that specifies durations as the first time a latent L\'evy process crosses a heterogeneous threshold. This likelihood is not generally known in closed form, but its Laplace transform is. Our approach to its computation relies on numerical methods for inverting Laplace transforms that exploit special properties of the first passage times of L\'evy processes. We use our method to implement a maximum likelihood estimator of the mixed hitting-time model in MATLAB. We illustrate the application of this estimator with an analysis of Kennan's (1985) strike data.
Therapeutics Data Commons: Machine Learning Datasets and Tasks for Drug Discovery and Development
Authors: Kexin Huang, Tianfan Fu, Wenhao Gao, Yue Zhao, Yusuf Roohani, Jure Leskovec, Connor W. Coley, Cao Xiao, Jimeng Sun, Marinka Zitnik
Date: 2021-02-18 00:00:00
Tasks: BIG-bench Machine Learning, Drug Discovery, Molecular Property Prediction, TDC ADMET Benchmarking Group, Therapeutics Data Commons

Therapeutics machine learning is an emerging field with incredible opportunities for innovatiaon and impact. However, advancement in this field requires formulation of meaningful learning tasks and careful curation of datasets. Here, we introduce Therapeutics Data Commons (TDC), the first unifying platform to systematically access and evaluate machine learning across the entire range of therapeutics. To date, TDC includes 66 AI-ready datasets spread across 22 learning tasks and spanning the discovery and development of safe and effective medicines. TDC also provides an ecosystem of tools and community resources, including 33 data functions and types of meaningful data splits, 23 strategies for systematic model evaluation, 17 molecule generation oracles, and 29 public leaderboards. All resources are integrated and accessible via an open Python library. We carry out extensive experiments on selected datasets, demonstrating that even the strongest algorithms fall short of solving key therapeutics challenges, including real dataset distributional shifts, multi-scale modeling of heterogeneous data, and robust generalization to novel data points. We envision that TDC can facilitate algorithmic and scientific advances and considerably accelerate machine-learning model development, validation and transition into biomedical and clinical implementation. TDC is an open-science initiative available at https://tdcommons.ai.
CReST: A Class-Rebalancing Self-Training Framework for Imbalanced Semi-Supervised Learning
Authors: Chen Wei, Kihyuk Sohn, Clayton Mellina, Alan Yuille, Fan Yang
Date: 2021-02-18 00:00:00
Proceeding: CVPR 2021 1

Semi-supervised learning on class-imbalanced data, although a realistic problem, has been under studied. While existing semi-supervised learning (SSL) methods are known to perform poorly on minority classes, we find that they still generate high precision pseudo-labels on minority classes. By exploiting this property, in this work, we propose Class-Rebalancing Self-Training (CReST), a simple yet effective framework to improve existing SSL methods on class-imbalanced data. CReST iteratively retrains a baseline SSL model with a labeled set expanded by adding pseudo-labeled samples from an unlabeled set, where pseudo-labeled samples from minority classes are selected more frequently according to an estimated class distribution. We also propose a progressive distribution alignment to adaptively adjust the rebalancing strength dubbed CReST+. We show that CReST and CReST+ improve state-of-the-art SSL algorithms on various class-imbalanced datasets and consistently outperform other popular rebalancing methods. Code has been made available at https://github.com/google-research/crest.
Knowledge Hypergraph Embedding Meets Relational Algebra
Authors: Bahare Fatemi, Perouz Taslakian, David Vazquez, David Poole
Date: 2021-02-18 00:00:00
Tasks: hypergraph embedding, Knowledge Graphs, Link Prediction

Embedding-based methods for reasoning in knowledge hypergraphs learn a representation for each entity and relation. Current methods do not capture the procedural rules underlying the relations in the graph. We propose a simple embedding-based model called ReAlE that performs link prediction in knowledge hypergraphs (generalized knowledge graphs) and can represent high-level abstractions in terms of relational algebra operations. We show theoretically that ReAlE is fully expressive and provide proofs and empirical evidence that it can represent a large subset of the primitive relational algebra operations, namely renaming, projection, set union, selection, and set difference. We also verify experimentally that ReAlE outperforms state-of-the-art models in knowledge hypergraph completion, and in representing each of these primitive relational algebra operations. For the latter experiment, we generate a synthetic knowledge hypergraph, for which we design an algorithm based on the Erdos-R'enyi model for generating random graphs.