Adversarial Training in Affective Computing and Sentiment Analysis: Recent Advances and Perspectives

Over the past few years, adversarial training has become an extremely active research topic and has been successfully applied to various Artificial Intelligence (AI) domains. As a potentially crucial technique for the development of the next generation of emotional AI systems, we herein provide a comprehensive overview of the application of adversarial training to affective computing and sentiment analysis. Various representative adversarial training algorithms are explained and discussed accordingly, aimed at tackling diverse challenges associated with emotional AI systems. Further, we highlight a range of potential future research directions. We expect that this overview will help facilitate the development of adversarial training for affective computing and sentiment analysis in both the academic and industrial communities

Deep Learning Techniques for Music Generation -- A Survey

This paper is a survey and an analysis of different ways of using deep learning (deep artificial neural networks) to generate musical content. We propose a methodology based on five dimensions for our analysis: Objective - What musical content is to be generated? Examples are: melody, polyphony, accompaniment or counterpoint. - For what destination and for what use? To be performed by a human(s) (in the case of a musical score), or by a machine (in the case of an audio file). Representation - What are the concepts to be manipulated? Examples are: waveform, spectrogram, note, chord, meter and beat. - What format is to be used? Examples are: MIDI, piano roll or text. - How will the representation be encoded? Examples are: scalar, one-hot or many-hot. Architecture - What type(s) of deep neural network is (are) to be used? Examples are: feedforward network, recurrent network, autoencoder or generative adversarial networks. Challenge - What are the limitations and open challenges? Examples are: variability, interactivity and creativity. Strategy - How do we model and control the process of generation? Examples are: single-step feedforward, iterative feedforward, sampling or input manipulation. For each dimension, we conduct a comparative analysis of various models and techniques and we propose some tentative multidimensional typology. This typology is bottom-up, based on the analysis of many existing deep-learning based systems for music generation selected from the relevant literature. These systems are described and are used to exemplify the various choices of objective, representation, architecture, challenge and strategy. The last section includes some discussion and some prospects.Comment: 209 pages. This paper is a simplified version of the book: J.-P. Briot, G. Hadjeres and F.-D. Pachet, Deep Learning Techniques for Music Generation, Computational Synthesis and Creative Systems, Springer, 201

Deep latent-variable models for neural text generation

Text generation aims to produce human-like natural language output for down-stream tasks. It covers a wide range of applications like machine translation, document summarization, dialogue generation and so on. Recently deep neural network-based end-to-end architectures are known to be data-hungry, and text generated from them usually suffer from low diversity, interpretability and controllability. As a result, it is difficult to trust the output from them in real-life applications. Deep latent-variable models, by specifying the probabilistic distribution over an intermediate latent process, provide a potential way of addressing these problems while maintaining the expressive power of deep neural networks. This presentation will explain how deep latent-variable models can improve over the standard encoder-decoder model for text generation. We will start from an introduction of encoder-decoder and deep latent-variable models, then go over popular optimization strategies, and finally elaborate on how latent variable models can help improve the diversity, interpretability and data efficiency in different applications of text generation tasks.Textgenerierung zielt darauf ab, eine menschenähnliche Textausgabe in natürlicher Sprache für Anwendungen zu erzeugen. Es deckt eine breite Palette von Anwendungen ab, wie maschinelle Übersetzung, Zusammenfassung von Dokumenten, Generierung von Dialogen usw. In letzter Zeit werden dafür hauptsächlich Endto- End-Architekturen auf der Basis von tiefen neuronalen Netzwerken verwendet. Der End-to-End-Ansatz fasst alle Submodule, die früher nach komplexen handgefertigten Regeln entworfen wurden, zu einer ganzheitlichen Codierungs- Decodierungs-Architektur zusammen. Bei ausreichenden Trainingsdaten kann eine Leistung auf dem neuesten Stand der Technik erzielt werden, ohne dass sprach- und domänenabhängiges Wissen erforderlich ist. Deep-Learning-Modelle sind jedoch als extrem datenhungrig bekannt und daraus generierter Text leidet normalerweise unter geringer Diversität, Interpretierbarkeit und Kontrollierbarkeit. Infolgedessen ist es schwierig, der Ausgabe von ihnen in realen Anwendungen zu vertrauen. Tiefe Modelle mit latenten Variablen bieten durch Angabe der Wahrscheinlichkeitsverteilung über einen latenten Zwischenprozess eine potenzielle Möglichkeit, diese Probleme zu lösen und gleichzeitig die Ausdruckskraft tiefer neuronaler Netze zu erhalten. Diese Dissertation zeigt, wie tiefe Modelle mit latenten Variablen Texterzeugung verbessern gegenüber dem üblichen Encoder-Decoder-Modell. Wir beginnen mit einer Einführung in Encoder-Decoder- und Deep Latent Variable-Modelle und gehen dann auf gängige Optimierungsstrategien wie Variationsinferenz, dynamische Programmierung, Soft Relaxation und Reinforcement Learning ein. Danach präsentieren wir Folgendes: 1. Wie latente Variablen Vielfalt der Texterzeugung verbessern können, indem ganzheitliche, latente Darstellungen auf Satzebene gelernt werden. Auf diese Weise kann zunächst eine latente Darstellung ausgewählt werden, aus der verschiedene Texte generiert werden können. Wir präsentieren effektive Algorithmen, um gleichzeitig das Lernen der Repräsentation und die Texterzeugung durch Variationsinferenz zu trainieren. Um die Einschränkungen der Variationsinferenz bezüglich Uni-Modalität und Inkonsistenz anzugehen, schlagen wir eine Wake-Sleep-Variation und ein auf Transinformation basierendes Trainingsziel vor. Experimente zeigen, dass sie sowohl die übliche Variationsinferenz als auch nicht-latente Variablenmodelle bei der Dialoggenerierung übertreffen. 2. Wie latente Variablen die Steuerbarkeit und Interpretierbarkeit der Texterzeugung verbessern können, indem feinkörnigere latente Spezifikationen zum Zwischengenerierungsprozess hinzugefügt werden. Wir veranschaulichen die Verwendung latenter Variablen für Wortausrichtung, Inhaltsauswahl, Textsegmentierung und Feldsegmentkorrespondenz. Wir leiten für sie effiziente Trainingsalgorithmen ab, damit die Texterzeugung explizit gesteuert werden kann, indem die latente Variable, die durch ihre Definition vom Menschen interpretiert werden kann, manipuliert wird. 3. Überwindung der Seltenheit von Trainingsmustern durch Behandlung von nicht parallelem Text als latente Variablen. Das Training kann wie beim Standard-EM-Algorithmus durchgeführt werden, der stabil konvergiert. Wir zeigen, dass es bei der Dialoggenerierung erfolgreich angewendet werden kann und den Generierungsraum durch die Verwendung von nicht-konversativem Text erheblich bereichert

딥러닝 기반 생성 모델을 이용한 자연어처리 데이터 증강 기법

학위논문(박사)--서울대학교 대학원 :공과대학 컴퓨터공학부,2020. 2. 이상구.Recent advances in generation capability of deep learning models have spurred interest in utilizing deep generative models for unsupervised generative data augmentation (GDA). Generative data augmentation aims to improve the performance of a downstream machine learning model by augmenting the original dataset with samples generated from a deep latent variable model. This data augmentation approach is attractive to the natural language processing community, because (1) there is a shortage of text augmentation techniques that require little supervision and (2) resource scarcity being prevalent. In this dissertation, we explore the feasibility of exploiting deep latent variable models for data augmentation on three NLP tasks: sentence classification, spoken language understanding (SLU) and dialogue state tracking (DST), represent NLP tasks of various complexities and properties -- SLU requires multi-task learning of text classification and sequence tagging, while DST requires the understanding of hierarchical and recurrent data structures. For each of the three tasks, we propose a task-specific latent variable model based on conditional, hierarchical and sequential variational autoencoders (VAE) for multi-modal joint modeling of linguistic features and the relevant annotations. We conduct extensive experiments to statistically justify our hypothesis that deep generative data augmentation is beneficial for all subject tasks. Our experiments show that deep generative data augmentation is effective for the select tasks, supporting the idea that the technique can potentially be utilized for other range of NLP tasks. Ablation and qualitative studies reveal deeper insight into the underlying mechanisms of generative data augmentation. As a secondary contribution, we also shed light onto the recurring posterior collapse phenomenon in autoregressive VAEs and, subsequently, propose novel techniques to reduce the model risk, which is crucial for proper training of complex VAE models, enabling them to synthesize better samples for data augmentation. In summary, this work intends to demonstrate and analyze the effectiveness of unsupervised generative data augmentation in NLP. Ultimately, our approach enables standardized adoption of generative data augmentation, which can be applied orthogonally to existing regularization techniques.최근 딥러닝 기반 생성 모델의 급격한 발전으로 이를 이용한 생성 기반 데이터 증강 기법(generative data augmentation, GDA)의 실현 가능성에 대한 기대가 커지고 있다. 생성 기반 데이터 증강 기법은 딥러닝 기반 잠재변수 모델에서 생성 된 샘플을 원본 데이터셋에 추가하여 연관된 태스크의 성능을 향상시키는 기술을 의미한다. 따라서 생성 기반 데이터 증강 기법은 데이터 공간에서 이뤄지는 정규화 기술의 한 형태로 간주될 수 있다. 이러한 딥러닝 기반 생성 모델의 새로운 활용 가능성은 자연어처리 분야에서 더욱 중요하게 부각되는 이유는 (1) 범용 가능한 텍스트 데이터 증강 기술의 부재와 (2) 텍스트 데이터의 희소성을 극복할 수 있는 대안이 필요하기 때문이다. 문제의 복잡도와 특징을 골고루 채집하기 위해 본 논문에서는 텍스트 분류(text classification), 순차적 레이블링과 멀티태스킹 기술이 필요한 발화 이해(spoken language understanding, SLU), 계층적이며 재귀적인 데이터 구조에 대한 고려가 필요한 대화 상태 추적(dialogue state tracking, DST) 등 세 가지 문제에서 딥러닝 기반 생성 모델을 활용한 데이터 증강 기법의 타당성에 대해 다룬다. 본 연구에서는 조건부, 계층적 및 순차적 variational autoencoder (VAE)에 기반하여 각 자연어처리 문제에 특화된 텍스트 및 연관 부착 정보를 동시에 생성하는 특수 딥러닝 생성 모델들을 제시하고, 다양한 하류 모델과 데이터셋을 다루는 등 폭 넓은 실험을 통해 딥 생성 모델 기반 데이터 증강 기법의 효과를 통계적으로 입증하였다. 부수적 연구에서는 자기회귀적(autoregressive) VAE에서 빈번히 발생하는 posterior collapse 문제에 대해 탐구하고, 해당 문제를 완화할 수 있는 신규 방안도 제안한다. 해당 방법을 생성적 데이터 증강에 필요한 복잡한 VAE 모델에 적용하였을 때, 생성 모델의 생성 질이 향상되어 데이터 증강 효과에도 긍정적인 영향을 미칠 수 있음을 검증하였다. 본 논문을 통해 자연어처리 분야에서 기존 정규화 기법과 병행 적용 가능한 비지도 형태의 데이터 증강 기법의 표준화를 기대해 볼 수 있다.1 Introduction 1 1.1 Motivation 1 1.2 Dissertation Overview 6 2 Background and Related Work 8 2.1 Deep Latent Variable Models 8 2.1.1 Variational Autoencoder (VAE) 10 2.1.2 Deep Generative Models and Text Generation 12 2.2 Data Augmentation 12 2.2.1 General Description 13 2.2.2 Categorization of Data Augmentation 14 2.2.3 Theoretical Explanations 21 2.3 Summary 24 3 Basic Task: Text Classi cation 25 3.1 Introduction 25 3.2 Our Approach 28 3.2.1 Proposed Models 28 3.2.2 Training with I-VAE 29 3.3 Experiments 31 3.3.1 Datasets 32 3.3.2 Experimental Settings 33 3.3.3 Implementation Details 34 3.3.4 Data Augmentation Results 36 3.3.5 Ablation Studies 39 3.3.6 Qualitative Analysis 40 3.4 Summary 45 4 Multi-task Learning: Spoken Language Understanding 46 4.1 Introduction 46 4.2 Related Work 48 4.3 Model Description 48 4.3.1 Framework Formulation 48 4.3.2 Joint Generative Model 49 4.4 Experiments 56 4.4.1 Datasets 56 4.4.2 Experimental Settings 57 4.4.3 Generative Data Augmentation Results 61 4.4.4 Comparison to Other State-of-the-art Results 63 4.4.5 Ablation Studies 63 4.5 Summary 67 5 Complex Data: Dialogue State Tracking 68 5.1 Introduction 68 5.2 Background and Related Work 70 5.2.1 Task-oriented Dialogue 70 5.2.2 Dialogue State Tracking 72 5.2.3 Conversation Modeling 72 5.3 Variational Hierarchical Dialogue Autoencoder (VHDA) 73 5.3.1 Notations 73 5.3.2 Variational Hierarchical Conversational RNN 74 5.3.3 Proposed Model 75 5.3.4 Posterior Collapse 82 5.4 Experimental Results 84 5.4.1 Experimental Settings 84 5.4.2 Data Augmentation Results 90 5.4.3 Intrinsic Evaluation - Language Evaluation 94 5.4.4 Qualitative Results 95 5.5 Summary 101 6 Conclusion 103 6.1 Summary 103 6.2 Limitations 104 6.3 Future Work 105Docto

Emotional body language synthesis for humanoid robots

Some of the chapters of this thesis are based on research published by the author. Chapter 4 is based on Marmpena M., Lim, A., and Dahl, T. S. (2018). How does the robot feel? Perception of valence and arousal in emotional body language. Paladyn, Journal of Behavioral Robotics, 9(1), 168-182. DOI: https://doi.org/10.1515/pjbr-2018-0012. Chapter 6 is based on Marmpena M., Lim, A., Dahl, T. S., and Hemion, N. (2019). Generating robotic emotional body language with Variational Autoencoders. In Proceedings of the 8th International Conference on Affective Computing and Intelligent Interaction (ACII), pages 545–551. DOI:10.1109/ACII.2019.8925459. Chapter 7 extends Marmpena M., Garcia, F., and Lim, A. (2020). Generating robotic emotional body language of targeted valence and arousal with Conditional Variational Autoencoders. In Companion of the 2020 ACM/IEEE International Conference on Human-Robot Interaction, HRI ’20, page 357–359. DOI: https://doi.org/10.1145/3371382.3378360. The designed or generated robotic emotional body language expressions data presented in this thesis are publicly available: https://github.com/minamar/rebl-pepper-dataIn the next decade, societies will witness a rise in service robots deployed in social environments, such as schools, homes, or shops, where they will operate as assistants, public relation agents, or companions. People are expected to willingly engage and collaborate with these robots to accomplish positive outcomes. To facilitate collaboration, robots need to comply with the behavioural and social norms used by humans in their daily interactions. One such behavioural norm is the expression of emotion through body language. Previous work on emotional body language synthesis for humanoid robots has been mainly focused on hand-coded design methods, often employing features extracted from human body language. However, the hand-coded design is cumbersome and results in a limited number of expressions with low variability. This limitation can be at the expense of user engagement since the robotic behaviours will appear repetitive and predictable, especially in long-term interaction. Furthermore, design approaches strictly based on human emotional body language might not transfer effectively on robots because of their simpler morphology. Finally, most previous work is using six or fewer basic emotion categories in the design and the evaluation phase of emotional expressions. This approach might result in lossy compression of the granularity in emotion expression. The current thesis presents a methodology for developing a complete framework of emotional body language generation for a humanoid robot, intending to address these three limitations. Our starting point is a small set of animations designed by professional animators with the robot morphology in mind. We conducted an initial user study to acquire reliable dimensional labels of valence and arousal for each animation. In the next step, we used the motion sequences from these animations to train a Variational Autoencoder, a deep learning model, to generate numerous new animations in an unsupervised setting. Finally, we extended the model to condition the generative process with valence and arousal attributes, and we conducted a user study to evaluate the interpretability of the animations in terms of valence, arousal, and dominance. The results indicate moderate to strong interpretability