pwc-archive/papers-with-abstracts huggingface dataset:
Redefining Neural Architecture Search of Heterogeneous Multi-Network Models by Characterizing Variation Operators and Model Components
Authors: Unai Garciarena, Roberto Santana, Alexander Mendiburu
Date: 2021-06-16 00:00:00
Tasks: Neural Architecture Search

With neural architecture search methods gaining ground on manually designed deep neural networks -even more rapidly as model sophistication escalates-, the research trend shifts towards arranging different and often increasingly complex neural architecture search spaces. In this conjuncture, delineating algorithms which can efficiently explore these search spaces can result in a significant improvement over currently used methods, which, in general, randomly select the structural variation operator, hoping for a performance gain. In this paper, we investigate the effect of different variation operators in a complex domain, that of multi-network heterogeneous neural models. These models have an extensive and complex search space of structures as they require multiple sub-networks within the general model in order to answer to different output types. From that investigation, we extract a set of general guidelines, whose application is not limited to that particular type of model, and are useful to determine the direction in which an architecture optimization method could find the largest improvement. To deduce the set of guidelines, we characterize both the variation operators, according to their effect on the complexity and performance of the model; and the models, relying on diverse metrics which estimate the quality of the different parts composing it.
Random feature neural networks learn Black-Scholes type PDEs without curse of dimensionality
Authors: Lukas Gonon
Date: 2021-06-14 00:00:00

This article investigates the use of random feature neural networks for learning Kolmogorov partial (integro-)differential equations associated to Black-Scholes and more general exponential L\'evy models. Random feature neural networks are single-hidden-layer feedforward neural networks in which only the output weights are trainable. This makes training particularly simple, but (a priori) reduces expressivity. Interestingly, this is not the case for Black-Scholes type PDEs, as we show here. We derive bounds for the prediction error of random neural networks for learning sufficiently non-degenerate Black-Scholes type models. A full error analysis is provided and it is shown that the derived bounds do not suffer from the curse of dimensionality. We also investigate an application of these results to basket options and validate the bounds numerically. These results prove that neural networks are able to \textit{learn} solutions to Black-Scholes type PDEs without the curse of dimensionality. In addition, this provides an example of a relevant learning problem in which random feature neural networks are provably efficient.
Personalized News Recommendation: Methods and Challenges
Authors: Chuhan Wu, Fangzhao Wu, Yongfeng Huang, Xing Xie
Date: 2021-06-16 00:00:00
Tasks: News Recommendation, Recommendation Systems

Personalized news recommendation is an important technique to help users find their interested news information and alleviate their information overload. It has been extensively studied over decades and has achieved notable success in improving users' news reading experience. However, there are still many unsolved problems and challenges that need to be further studied. To help researchers master the advances in personalized news recommendation over the past years, in this paper we present a comprehensive overview of personalized news recommendation. Instead of following the conventional taxonomy of news recommendation methods, in this paper we propose a novel perspective to understand personalized news recommendation based on its core problems and the associated techniques and challenges. We first review the techniques for tackling each core problem in a personalized news recommender system and the challenges they face. Next, we introduce the public datasets and evaluation methods for personalized news recommendation. We then discuss the key points on improving the responsibility of personalized news recommender systems. Finally, we raise several research directions that are worth investigating in the future. This paper can provide up-to-date and comprehensive views to help readers understand the personalized news recommendation field. We hope this paper can facilitate research on personalized news recommendation as well as related fields in natural language processing and data mining.
TSSuBERT: Tweet Stream Summarization Using BERT
Authors: Alexis Dusart, Karen Pinel-Sauvagnat, Gilles Hubert
Date: 2021-06-16 00:00:00

The development of deep neural networks and the emergence of pre-trained language models such as BERT allow to increase performance on many NLP tasks. However, these models do not meet the same popularity for tweet summarization, which can probably be explained by the lack of existing collections for training and evaluation. Our contribution in this paper is twofold : (1) we introduce a large dataset for Twitter event summarization, and (2) we propose a neural model to automatically summarize huge tweet streams. This extractive model combines in an original way pre-trained language models and vocabulary frequency-based representations to predict tweet salience. An additional advantage of the model is that it automatically adapts the size of the output summary according to the input tweet stream. We conducted experiments using two different Twitter collections, and promising results are observed in comparison with state-of-the-art baselines.
Universal and specific features of Ukrainian economic research: publication analysis based on Crossref data
Authors: O. Mryglod, S. Nazarovets, S. Kozmenko
Date: 2021-06-16 00:00:00

Our study is one of the first examples of multidimensional and longitudinal disciplinary analysis at the national level based on Crossref data. We present a large-scale quantitative analysis of Ukrainian economics. This study is not yet another example of research aimed at ranking of local journals, authors or institutions, but rather exploring general tendencies that can be compared to other countries or regions. We study different aspects of Ukrainian economics output. In particular, the collaborative nature, geographic landscape and some peculiarities of citation statistics are investigated. We have found that Ukrainian economics is characterized by a comparably small share of co-authored publications, however, it demonstrates the tendency towards more collaborative output. Based on our analysis, we discuss specific and universal features of Ukrainian economic research. The importance of supporting various initiatives aimed at enriching open scholarly metadata is considered. A comprehensive and high-quality meta description of publications is probably the shortest path to a better understanding of national trends, especially for non-English speaking countries. The results of our analysis can be used to better understand Ukrainian economic research and support research policy decisions.
FAIR: Fairness-Aware Information Retrieval Evaluation
Authors: Ruoyuan Gao, Yingqiang Ge, Chirag Shah
Date: 2021-06-16 00:00:00
Tasks: Diversity, Fairness, Information Retrieval, Recommendation Systems, Retrieval

With the emerging needs of creating fairness-aware solutions for search and recommendation systems, a daunting challenge exists of evaluating such solutions. While many of the traditional information retrieval (IR) metrics can capture the relevance, diversity, and novelty for the utility with respect to users, they are not suitable for inferring whether the presented results are fair from the perspective of responsible information exposure. On the other hand, existing fairness metrics do not account for user utility or do not measure it adequately. To address this problem, we propose a new metric called FAIR. By unifying standard IR metrics and fairness measures into an integrated metric, this metric offers a new perspective for evaluating fairness-aware ranking results. Based on this metric, we developed an effective ranking algorithm that jointly optimized user utility and fairness. The experimental results showed that our FAIR metric could highlight results with good user utility and fair information exposure. We showed how FAIR related to a set of existing utility and fairness metrics and demonstrated the effectiveness of our FAIR-based algorithm. We believe our work opens up a new direction of pursuing a metric for evaluating and implementing the FAIR systems.
Combining Lexical and Dense Retrieval for Computationally Efficient Multi-hop Question Answering
Authors: Georgios Sidiropoulos, Nikos Voskarides, Svitlana Vakulenko, Evangelos Kanoulas
Date: 2021-06-15 00:00:00
Proceeding: EMNLP (sustainlp) 2021 11
Tasks: Multi-hop Question Answering, Open-Domain Question Answering, Passage Retrieval, Question Answering, Retrieval

In simple open-domain question answering (QA), dense retrieval has become one of the standard approaches for retrieving the relevant passages to infer an answer. Recently, dense retrieval also achieved state-of-the-art results in multi-hop QA, where aggregating information from multiple pieces of information and reasoning over them is required. Despite their success, dense retrieval methods are computationally intensive, requiring multiple GPUs to train. In this work, we introduce a hybrid (lexical and dense) retrieval approach that is highly competitive with the state-of-the-art dense retrieval models, while requiring substantially less computational resources. Additionally, we provide an in-depth evaluation of dense retrieval methods on limited computational resource settings, something that is missing from the current literature.
Cross Modality Knowledge Distillation for Multi-Modal Aerial View Object Classification
Authors: Lehan Yang; Kele Xu
Date: 2021-06-19 00:00:00
Proceeding: IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR) Workshops 2021 6
Tasks: Image Classification, Knowledge Distillation, Monocular 3D Object Detection, Object, object-detection, Object Detection, Transfer Learning

In the case of bad weather or low lighting conditions, a single sensor may not be able to capture enough information for object identification. Compared with the traditional optical image, synthetic aperture radar (SAR) imaging has greater advantages, such as the ability to penetrate through fog and smoke. However, SAR images are of low resolution and contaminated by high-level speckle noise. As a result, it is of great difficulty to extract powerful and robust features from the SAR images. In this paper, we explored whether multiple imaging modalities can improve the object detection performance. Here, we propose a Cross Modality Knowledge Distillation (CMKD) paradigm, and explore two different network structures named CMKD-s and CMKD-m for the object classification task. Specifically, CMKD-s transfers the information captured by the two sensors using the online knowledge distillation, which can achieve cross-modal knowledge sharing and enhance the robustness of the aerial view object classification model. Moreover, leveraging the semi-supervised enhanced training, we proposed a novel method named CMKD-m, which strengthens the model for mutual knowledge transfer. Through quantitative comparison, we found that CMKD-s and CMKD-m outperform the method without knowledge transfer, on the NTIRE2021 SAR-EO challenge dataset.
Fungi anaesthesia
Authors: Andrew Adamatzky, Antoni Gandia
Date: 2021-06-13 00:00:00

Electrical activity of fungus \emph{Pleurotus ostreatus} is characterised by slow (hours) irregular waves of baseline potential drift and fast (minutes) action potential likes spikes of the electrical potential. An exposure of the mycelium colonised substrate to a chloroform vapour lead to several fold decrease of the baseline potential waves and increase of their duration. The chloroform vapour also causes either complete cessation of spiking activity or substantial reduction of the spiking frequency. Removal of the chloroform vapour from the growth containers leads to a gradual restoration of the mycelium electrical activity.
Multi-resolution intra-predictive coding of 3D point cloud attributes
Authors: Eduardo Pavez, Andre L. Souto, Ricardo L. De Queiroz, Antonio Ortega
Date: 2021-06-16 00:00:00

We propose an intra frame predictive strategy for compression of 3D point cloud attributes. Our approach is integrated with the region adaptive graph Fourier transform (RAGFT), a multi-resolution transform formed by a composition of localized block transforms, which produces a set of low pass (approximation) and high pass (detail) coefficients at multiple resolutions. Since the transform operations are spatially localized, RAGFT coefficients at a given resolution may still be correlated. To exploit this phenomenon, we propose an intra-prediction strategy, in which decoded approximation coefficients are used to predict uncoded detail coefficients. The prediction residuals are then quantized and entropy coded. For the 8i dataset, we obtain gains up to 0.5db as compared to intra predicted point cloud compresion based on the region adaptive Haar transform (RAHT).
Exponential Approximation of Band-limited Functions from Nonuniform Sampling by Regularization Methods
Authors: Yunfei Yang, Haizhang Zhang
Date: 2021-06-16 00:00:00

Reconstructing a band-limited function from its finite sample data is a fundamental task in signal analysis. A Gaussian regularized Shannon sampling series has been proved to be able to achieve exponential convergence for uniform sampling. Whether such an exponential convergence can also be achieved for nonuniform sampling by regularization methods was unresolved. In this paper, we give an affirmative and constructive answer to this question. Specifically, we show that one can recover a band-limited function by Gaussian or hyper-Gaussian regularized nonuniform sampling series with an exponential convergence rate. Our analysis is based on the residue theorem in complex analysis, which is used to represent the truncated error by a contour integral. Several concrete examples of nonuniform sampling with exponential convergence will be presented.
Momentum-inspired Low-Rank Coordinate Descent for Diagonally Constrained SDPs
Authors: Junhyung Lyle Kim, Jose Antonio Lara Benitez, Mohammad Taha Toghani, Cameron Wolfe, Zhiwei Zhang, Anastasios Kyrillidis
Date: 2021-06-16 00:00:00

We present a novel, practical, and provable approach for solving diagonally constrained semi-definite programming (SDP) problems at scale using accelerated non-convex programming. Our algorithm non-trivially combines acceleration motions from convex optimization with coordinate power iteration and matrix factorization techniques. The algorithm is extremely simple to implement, and adds only a single extra hyperparameter -- momentum. We prove that our method admits local linear convergence in the neighborhood of the optimum and always converges to a first-order critical point. Experimentally, we showcase the merits of our method on three major application domains: MaxCut, MaxSAT, and MIMO signal detection. In all cases, our methodology provides significant speedups over non-convex and convex SDP solvers -- 5X faster than state-of-the-art non-convex solvers, and 9 to 10^3 X faster than convex SDP solvers -- with comparable or improved solution quality.
A Flow-Based Neural Network for Time Domain Speech Enhancement
Authors: Martin Strauss, Bernd Edler
Date: 2021-06-16 00:00:00
Tasks: Density Estimation, Speech Enhancement, Speech Synthesis

Speech enhancement involves the distinction of a target speech signal from an intrusive background. Although generative approaches using Variational Autoencoders or Generative Adversarial Networks (GANs) have increasingly been used in recent years, normalizing flow (NF) based systems are still scarse, despite their success in related fields. Thus, in this paper we propose a NF framework to directly model the enhancement process by density estimation of clean speech utterances conditioned on their noisy counterpart. The WaveGlow model from speech synthesis is adapted to enable direct enhancement of noisy utterances in time domain. In addition, we demonstrate that nonlinear input companding benefits the model performance by equalizing the distribution of input samples. Experimental evaluation on a publicly available dataset shows comparable results to current state-of-the-art GAN-based approaches, while surpassing the chosen baselines using objective evaluation metrics.
Enriching Source Style Transfer in Recognition-Synthesis based Non-Parallel Voice Conversion
Authors: Zhichao Wang, Xinyong Zhou, Fengyu Yang, Tao Li, Hongqiang Du, Lei Xie, Wendong Gan, Haitao Chen, Hai Li
Date: 2021-06-16 00:00:00
Tasks: Style Transfer, Voice Conversion

Current voice conversion (VC) methods can successfully convert timbre of the audio. As modeling source audio's prosody effectively is a challenging task, there are still limitations of transferring source style to the converted speech. This study proposes a source style transfer method based on recognition-synthesis framework. Previously in speech generation task, prosody can be modeled explicitly with prosodic features or implicitly with a latent prosody extractor. In this paper, taking advantages of both, we model the prosody in a hybrid manner, which effectively combines explicit and implicit methods in a proposed prosody module. Specifically, prosodic features are used to explicit model prosody, while VAE and reference encoder are used to implicitly model prosody, which take Mel spectrum and bottleneck feature as input respectively. Furthermore, adversarial training is introduced to remove speaker-related information from the VAE outputs, avoiding leaking source speaker information while transferring style. Finally, we use a modified self-attention based encoder to extract sentential context from bottleneck features, which also implicitly aggregates the prosodic aspects of source speech from the layered representations. Experiments show that our approach is superior to the baseline and a competitive system in terms of style transfer; meanwhile, the speech quality and speaker similarity are well maintained.
DCCRN+: Channel-wise Subband DCCRN with SNR Estimation for Speech Enhancement
Authors: Shubo Lv, Yanxin Hu, Shimin Zhang, Lei Xie
Date: 2021-06-16 00:00:00
Tasks: Decoder, Speech Enhancement

Deep complex convolution recurrent network (DCCRN), which extends CRN with complex structure, has achieved superior performance in MOS evaluation in Interspeech 2020 deep noise suppression challenge (DNS2020). This paper further extends DCCRN with the following significant revisions. We first extend the model to sub-band processing where the bands are split and merged by learnable neural network filters instead of engineered FIR filters, leading to a faster noise suppressor trained in an end-to-end manner. Then the LSTM is further substituted with a complex TF-LSTM to better model temporal dependencies along both time and frequency axes. Moreover, instead of simply concatenating the output of each encoder layer to the input of the corresponding decoder layer, we use convolution blocks to first aggregate essential information from the encoder output before feeding it to the decoder layers. We specifically formulate the decoder with an extra a priori SNR estimation module to maintain good speech quality while removing noise. Finally a post-processing module is adopted to further suppress the unnatural residual noise. The new model, named DCCRN+, has surpassed the original DCCRN as well as several competitive models in terms of PESQ and DNSMOS, and has achieved superior performance in the new Interspeech 2021 DNS challenge
Multi-Speaker ASR Combining Non-Autoregressive Conformer CTC and Conditional Speaker Chain
Authors: Pengcheng Guo, Xuankai Chang, Shinji Watanabe, Lei Xie
Date: 2021-06-16 00:00:00
Tasks: Automatic Speech Recognition, Automatic Speech Recognition (ASR), speech-recognition, Speech Recognition

Non-autoregressive (NAR) models have achieved a large inference computation reduction and comparable results with autoregressive (AR) models on various sequence to sequence tasks. However, there has been limited research aiming to explore the NAR approaches on sequence to multi-sequence problems, like multi-speaker automatic speech recognition (ASR). In this study, we extend our proposed conditional chain model to NAR multi-speaker ASR. Specifically, the output of each speaker is inferred one-by-one using both the input mixture speech and previously-estimated conditional speaker features. In each step, a NAR connectionist temporal classification (CTC) encoder is used to perform parallel computation. With this design, the total inference steps will be restricted to the number of mixed speakers. Besides, we also adopt the Conformer and incorporate an intermediate CTC loss to improve the performance. Experiments on WSJ0-Mix and LibriMix corpora show that our model outperforms other NAR models with only a slight increase of latency, achieving WERs of 22.3% and 24.9%, respectively. Moreover, by including the data of variable numbers of speakers, our model can even better than the PIT-Conformer AR model with only 1/7 latency, obtaining WERs of 19.9% and 34.3% on WSJ0-2mix and WSJ0-3mix sets. All of our codes are publicly available at https://github.com/pengchengguo/espnet/tree/conditional-multispk.
Detection of Consonant Errors in Disordered Speech Based on Consonant-vowel Segment Embedding
Authors: Si-Ioi Ng, Cymie Wing-Yee Ng, Jingyu Li, Tan Lee
Date: 2021-06-16 00:00:00

Speech sound disorder (SSD) refers to a type of developmental disorder in young children who encounter persistent difficulties in producing certain speech sounds at the expected age. Consonant errors are the major indicator of SSD in clinical assessment. Previous studies on automatic assessment of SSD revealed that detection of speech errors concerning short and transitory consonants is less satisfactory. This paper investigates a neural network based approach to detecting consonant errors in disordered speech using consonant-vowel (CV) diphone segment in comparison to using consonant monophone segment. The underlying assumption is that the vowel part of a CV segment carries important information of co-articulation from the consonant. Speech embeddings are extracted from CV segments by a recurrent neural network model. The similarity scores between the embeddings of the test segment and the reference segments are computed to determine if the test segment is the expected consonant or not. Experimental results show that using CV segments achieves improved performance on detecting speech errors concerning those "difficult" consonants reported in the previous studies.