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Machine Learning (ML) and Neural Networks (NN)… An Intuitive Walkthrough

#artificialintelligence

The use of computer systems to learn and adapt without explicitly coded instructions; primarily utilized through statistical models and a machine's ability to draw inferences, and analyze certain patterns that may present themselves in data. The use of computer systems to mimic Biological Neural Networks (BNN); often utilized through a series of algorithms used to discover relationships between information, analyzed in an approach that mimics the inner workings of the human brain. A multi-layered Neural Network is referred to as a Deep Neural Network, lending itself over to Deep Learning (DL). I provided these definitions to multiple different people and got the exact same response each time… "I was able to understand absolutely nothing from that" To be honest, I can't really blame them. There's no doubt that these definitions present themselves in a way that's incredibly difficult to decode and understand. Simply reading these definitions adds very little value to our understanding of these incredibly complex fields. This article aims to take a deeper dive into these definitions to try and achieve a fundamental understanding of the inner workings of artificial intelligence, machine learning, and neural networks, as well as their relationships with one another intuitively. There are various different facets of machine learning, as well as how it functions. Hopefully, by the end of this article, your perception of ML will shift from one that associates it with magic, to one that's oriented around mathematics and logic.


AI Explainability -- Explained

#artificialintelligence

Machine learning (ML) is powerful. Its models and their interpretability have been the subject of increasing attention over the last few years, as they have grown more powerful and widely used. With the right data, machine learning models can predict new data extremely well with little to no interpretability, but interpretability is important for many reasons. Model interpretability allows us to address some of our most fundamental questions about the predictions that a model makes: What features did you learn? Why did you make this prediction?


Supervised Compression for Resource-Constrained Edge Computing Systems

arXiv.org Artificial Intelligence

There has been much interest in deploying deep learning algorithms on low-powered devices, including smartphones, drones, and medical sensors. However, full-scale deep neural networks are often too resource-intensive in terms of energy and storage. As a result, the bulk part of the machine learning operation is therefore often carried out on an edge server, where the data is compressed and transmitted. However, compressing data (such as images) leads to transmitting information irrelevant to the supervised task. Another popular approach is to split the deep network between the device and the server while compressing intermediate features. To date, however, such split computing strategies have barely outperformed the aforementioned naive data compression baselines due to their inefficient approaches to feature compression. This paper adopts ideas from knowledge distillation and neural image compression to compress intermediate feature representations more efficiently. Our supervised compression approach uses a teacher model and a student model with a stochastic bottleneck and learnable prior for entropy coding (Entropic Student). We compare our approach to various neural image and feature compression baselines in three vision tasks and found that it achieves better supervised rate-distortion performance while maintaining smaller end-to-end latency. We furthermore show that the learned feature representations can be tuned to serve multiple downstream tasks.


CATRO: Channel Pruning via Class-Aware Trace Ratio Optimization

arXiv.org Artificial Intelligence

Deep convolutional neural networks are shown to be overkill with high parametric and computational redundancy in many application scenarios, and an increasing number of works have explored model pruning to obtain lightweight and efficient networks. However, most existing pruning approaches are driven by empirical heuristics and rarely consider the joint impact of channels, leading to unguaranteed and suboptimal performance. In this paper, we propose a novel channel pruning method via class-aware trace ratio optimization (CATRO) to reduce the computational burden and accelerate the model inference. Utilizing class information from a few samples, CATRO measures the joint impact of multiple channels by feature space discriminations and consolidates the layer-wise impact of preserved channels. By formulating channel pruning as a submodular set function maximization problem, CATRO solves it efficiently via a two-stage greedy iterative optimization procedure. More importantly, we present theoretical justifications on convergence and performance of CATRO. Experimental results demonstrate that CATRO achieves higher accuracy with similar computation cost or lower computation cost with similar accuracy than other state-of-the-art channel pruning algorithms. In addition, because of its class-aware property, CATRO is suitable to prune efficient networks adaptively for various classification subtasks, enhancing handy deployment and usage of deep networks in real-world applications.


Merging Two Cultures: Deep and Statistical Learning

arXiv.org Machine Learning

Merging the two cultures of deep and statistical learning provides insights into structured high-dimensional data. Traditional statistical modeling is still a dominant strategy for structured tabular data. Deep learning can be viewed through the lens of generalized linear models (GLMs) with composite link functions. Sufficient dimensionality reduction (SDR) and sparsity performs nonlinear feature engineering. We show that prediction, interpolation and uncertainty quantification can be achieved using probabilistic methods at the output layer of the model. Thus a general framework for machine learning arises that first generates nonlinear features (a.k.a factors) via sparse regularization and stochastic gradient optimisation and second uses a stochastic output layer for predictive uncertainty. Rather than using shallow additive architectures as in many statistical models, deep learning uses layers of semi affine input transformations to provide a predictive rule. Applying these layers of transformations leads to a set of attributes (a.k.a features) to which predictive statistical methods can be applied. Thus we achieve the best of both worlds: scalability and fast predictive rule construction together with uncertainty quantification. Sparse regularisation with un-supervised or supervised learning finds the features. We clarify the duality between shallow and wide models such as PCA, PPR, RRR and deep but skinny architectures such as autoencoders, MLPs, CNN, and LSTM. The connection with data transformations is of practical importance for finding good network architectures. By incorporating probabilistic components at the output level we allow for predictive uncertainty. For interpolation we use deep Gaussian process and ReLU trees for classification. We provide applications to regression, classification and interpolation. Finally, we conclude with directions for future research.


Dual Encoding U-Net for Spatio-Temporal Domain Shift Frame Prediction

arXiv.org Artificial Intelligence

The landscape of city-wide mobility behaviour has altered significantly over the past 18 months. The ability to make accurate and reliable predictions on such behaviour has likewise changed drastically with COVID-19 measures impacting how populations across the world interact with the different facets of mobility. This raises the question: "How does one use an abundance of pre-covid mobility data to make predictions on future behaviour in a present/post-covid environment?" This paper seeks to address this question by introducing an approach for traffic frame prediction using a lightweight Dual-Encoding U-Net built using only 12 Convolutional layers that incorporates a novel approach to skip-connections between Convolutional LSTM layers.


Model-based Reinforcement Learning for Service Mesh Fault Resiliency in a Web Application-level

arXiv.org Artificial Intelligence

Microservice-based architectures enable different aspects of web applications to be created and updated independently, even after deployment. Associated technologies such as service mesh provide application-level fault resilience through attribute configurations that govern the behavior of request-response service -- and the interactions among them -- in the presence of failures. While this provides tremendous flexibility, the configured values of these attributes -- and the relationships among them -- can significantly affect the performance and fault resilience of the overall application. Furthermore, it is impossible to determine the best and worst combinations of attribute values with respect to fault resiliency via testing, due to the complexities of the underlying distributed system and the many possible attribute value combinations. In this paper, we present a model-based reinforcement learning workflow towards service mesh fault resiliency. Our approach enables the prediction of the most significant fault resilience behaviors at a web application-level, scratching from single service to aggregated multi-service management with efficient agent collaborations.


Optimizing Multi-Taper Features for Deep Speaker Verification

arXiv.org Artificial Intelligence

Multi-taper estimators provide low-variance power spectrum estimates that can be used in place of the windowed discrete Fourier transform (DFT) to extract speech features such as mel-frequency cepstral coefficients (MFCCs). Even if past work has reported promising automatic speaker verification (ASV) results with Gaussian mixture model-based classifiers, the performance of multi-taper MFCCs with deep ASV systems remains an open question. Instead of a static-taper design, we propose to optimize the multi-taper estimator jointly with a deep neural network trained for ASV tasks. With a maximum improvement on the SITW corpus of 25.8% in terms of equal error rate over the static-taper, our method helps preserve a balanced level of leakage and variance, providing more robustness.


ModEL: A Modularized End-to-end Reinforcement Learning Framework for Autonomous Driving

arXiv.org Artificial Intelligence

Heated debates continue over the best autonomous driving framework. The classic modular pipeline is widely adopted in the industry owing to its great interpretability and stability, whereas the end-to-end paradigm has demonstrated considerable simplicity and learnability along with the rise of deep learning. We introduce a new modularized end-to-end reinforcement learning framework (ModEL) for autonomous driving, which combines the merits of both previous approaches. The autonomous driving stack of ModEL is decomposed into perception, planning, and control module, leveraging scene understanding, end-to-end reinforcement learning, and PID control respectively. Furthermore, we build a fully functional autonomous vehicle to deploy this framework. Through extensive simulation and real-world experiments, our framework has shown great generalizability to various complicated scenarios and outperforms the competing baselines.


Wide Neural Networks Forget Less Catastrophically

arXiv.org Artificial Intelligence

Machine learning is relying more and more on training large models on large static datasets to reach impressive results (Kaplan et al., 2020; Lazaridou et al., 2021; Hombaiah et al., 2021). However, the real world is changing over time and new information is becoming available at an unprecedented rate (Lazaridou et al., 2021; Hombaiah et al., 2021). In such real world problems, the learning agent is exposed to a continuous stream of data, with potentially changing data distribution, and it has to absorb new information efficiently while not being able to iterate on previous data as freely as wanted due to time, sample, compute, privacy, or environmental complexity issues (Parisi et al., 2018). To overcome these inefficiencies, fields, such as Continual learning (CL) (Ring et al., 1994) or lifelong learning (Thrun, 1995) are gaining a lot of attention recently. One of the key challenges in continual learning models is the abrupt erasure of previous knowledge, referred to as Catastrophic Forgetting (CF) (McCloskey and Cohen, 1989). Alleviating catastrophic forgetting has attracted a lot of attention lately, and many interesting solutions are proposed to partly overcome the issue (e.g., Toneva et al., 2018; Nguyen et al., 2019; Hsu et al., 2018; Li et al., 2019; Wallingford et al., 2020). These solutions vary in degree of complexity from simple replay-based methods to complicated regularization or network expansion-based methods. Unfortunately, however, there is not much fundamental understanding of the intrinsic properties of neural networks that affects continual learning performance through catastrophic forgetting or forward/backward transfer (Mirzadeh et al., 2020). Work done during an internship at DeepMind.