Statistical Learning
Nengo: A New Neural Network Building and Deployment Tool
Nengo is a useful tool for building and testing neural networks, besides deep learning, it helps in working memory, path integration, etc. It also contains Add-ons and Simulators but the two main important Add-ons are KerasSpiking and PyTorchSpiking for spiking neural networks in their respective frameworks. To install the Nengo use the pip command in the anaconda prompt. To use the interactive Nengo GUI, we need to install the nengo GUI. After installing GUI, we can use the nengo command to open the interactive GUI of nengo.
RATT: Leveraging Unlabeled Data to Guarantee Generalization
Garg, Saurabh, Balakrishnan, Sivaraman, Kolter, J. Zico, Lipton, Zachary C.
To assess generalization, machine learning scientists typically either (i) bound the generalization gap and then (after training) plug in the empirical risk to obtain a bound on the true risk; or (ii) validate empirically on holdout data. However, (i) typically yields vacuous guarantees for overparameterized models. Furthermore, (ii) shrinks the training set and its guarantee erodes with each re-use of the holdout set. In this paper, we introduce a method that leverages unlabeled data to produce generalization bounds. After augmenting our (labeled) training set with randomly labeled fresh examples, we train in the standard fashion. Whenever classifiers achieve low error on clean data and high error on noisy data, our bound provides a tight upper bound on the true risk. We prove that our bound is valid for 0-1 empirical risk minimization and with linear classifiers trained by gradient descent. Our approach is especially useful in conjunction with deep learning due to the early learning phenomenon whereby networks fit true labels before noisy labels but requires one intuitive assumption. Empirically, on canonical computer vision and NLP tasks, our bound provides non-vacuous generalization guarantees that track actual performance closely. This work provides practitioners with an option for certifying the generalization of deep nets even when unseen labeled data is unavailable and provides theoretical insights into the relationship between random label noise and generalization.
One-pass Stochastic Gradient Descent in Overparametrized Two-layer Neural Networks
There has been a recent surge of interest in understanding the convergence of gradient descent (GD) and stochastic gradient descent (SGD) in overparameterized neural networks. Most previous works assume that the training data is provided a priori in a batch, while less attention has been paid to the important setting where the training data arrives in a stream. In this paper, we study the streaming data setup and show that with overparamterization and random initialization, the prediction error of two-layer neural networks under one-pass SGD converges in expectation. The convergence rate depends on the eigen-decomposition of the integral operator associated with the so-called neural tangent kernel (NTK). A key step of our analysis is to show a random kernel function converges to the NTK with high probability using the VC dimension and McDiarmid's inequality.
Stochastic Mutual Information Gradient Estimation for Dimensionality Reduction Networks
Ozdenizci, Ozan, Erdogmus, Deniz
Applications in various research fields have developed different domain-specific methods for feature learning and subsequent supervised model training [24, 26, 28]. Many exploratory applications in practice are further characterized by high-dimensional feature representations where the dimensionality reduction problem is to be addressed. One traditional approach towards supervised dimensionality reduction is feature selection, referring to the process of selecting the most class-informative subset from the high-dimensional feature set and discarding others [16]. Particularly, feature selection based on information theoretic criteria (e.g., maximum mutual information) have shown significant promise in earlier studies [2, 25]. Although selecting a class-relevant subset of features leads to intuitively interpretable and preferable learning algorithms, feature ranking and selection algorithms are known to potentially yield sub-optimal solutions due to their inability to thoroughly assess feature dependencies [10, 44]. In that regard, feature transformation based dimensionality reduction methods provide a more robust alternative [16], which have been also studied in the form of information theoretic projections or rotations [11, 19, 43].
NUQSGD: Provably Communication-efficient Data-parallel SGD via Nonuniform Quantization
Ramezani-Kebrya, Ali, Faghri, Fartash, Markov, Ilya, Aksenov, Vitalii, Alistarh, Dan, Roy, Daniel M.
As the size and complexity of models and datasets grow, so does the need for communication-efficient variants of stochastic gradient descent that can be deployed to perform parallel model training. One popular communication-compression method for data-parallel SGD is QSGD (Alistarh et al., 2017), which quantizes and encodes gradients to reduce communication costs. The baseline variant of QSGD provides strong theoretical guarantees, however, for practical purposes, the authors proposed a heuristic variant which we call QSGDinf, which demonstrated impressive empirical gains for distributed training of large neural networks. In this paper, we build on this work to propose a new gradient quantization scheme, and show that it has both stronger theoretical guarantees than QSGD, and matches and exceeds the empirical performance of the QSGDinf heuristic and of other compression methods.
Stochastic Block-ADMM for Training Deep Networks
Khorram, Saeed, Fu, Xiao, Danesh, Mohamad H., Qi, Zhongang, Fuxin, Li
In this paper, we propose Stochastic Block-ADMM as an approach to train deep neural networks in batch and online settings. Our method works by splitting neural networks into an arbitrary number of blocks and utilizes auxiliary variables to connect these blocks while optimizing with stochastic gradient descent. This allows training deep networks with non-differentiable constraints where conventional backpropagation is not applicable. An application of this is supervised feature disentangling, where our proposed DeepFacto inserts a non-negative matrix factorization (NMF) layer into the network. Since backpropagation only needs to be performed within each block, our approach alleviates vanishing gradients and provides potentials for parallelization. We prove the convergence of our proposed method and justify its capabilities through experiments in supervised and weakly-supervised settings.
Comprehensive Review On Twin Support Vector Machines
Tanveer, M., Rajani, T., Rastogi, R., Shao, Y. H.
Twin support vector machine (TSVM) and twin support vector regression (TSVR) are newly emerging efficient machine learning techniques which offer promising solutions for classification and regression challenges respectively. TSVM is based upon the idea to identify two nonparallel hyperplanes which classify the data points to their respective classes. It requires to solve two small sized quadratic programming problems (QPPs) in lieu of solving single large size QPP in support vector machine (SVM) while TSVR is formulated on the lines of TSVM and requires to solve two SVM kind problems. Although there has been good research progress on these techniques; there is limited literature on the comparison of different variants of TSVR. Thus, this review presents a rigorous analysis of recent research in TSVM and TSVR simultaneously mentioning their limitations and advantages. To begin with we first introduce the basic theory of TSVM and then focus on the various improvements and applications of TSVM, and then we introduce TSVR and its various enhancements. Finally, we suggest future research and development prospects.
One-shot learning for acoustic identification of bird species in non-stationary environments
Acconcjaioco, Michelangelo, Ntalampiras, Stavros
This work introduces the one-shot learning paradigm in the computational bioacoustics domain. Even though, most of the related literature assumes availability of data characterizing the entire class dictionary of the problem at hand, that is rarely true as a habitat's species composition is only known up to a certain extent. Thus, the problem needs to be addressed by methodologies able to cope with non-stationarity. To this end, we propose a framework able to detect changes in the class dictionary and incorporate new classes on the fly. We design an one-shot learning architecture composed of a Siamese Neural Network operating in the logMel spectrogram space. We extensively examine the proposed approach on two datasets of various bird species using suitable figures of merit. Interestingly, such a learning scheme exhibits state of the art performance, while taking into account extreme non-stationarity cases.
Visually grounded models of spoken language: A survey of datasets, architectures and evaluation techniques
This survey provides an overview of the evolution of visually grounded models of spoken language over the last 20 years. Such models are inspired by the observation that when children pick up a language, they rely on a wide range of indirect and noisy clues, crucially including signals from the visual modality co-occurring with spoken utterances. Several fields have made important contributions to this approach to modeling or mimicking the process of learning language: Machine Learning, Natural Language and Speech Processing, Computer Vision and Cognitive Science. The current paper brings together these contributions in order to provide a useful introduction and overview for practitioners in all these areas. We discuss the central research questions addressed, the timeline of developments, and the datasets which enabled much of this work. We then summarize the main modeling architectures and offer an exhaustive overview of the evaluation metrics and analysis techniques.
Essential Machine Learning Interview Questions and Concepts
Q2: What is the difference between supervised and unsupervised machine learning? Q3: How is KNN different from k-means clustering? Q5: Define precision and recall. This course will help you to answer some of the questions asked in Interviews related to Machine Learning. Machine learning is the science of getting computers to act without being explicitly programmed. Machine learning is a method of data analysis that automates analytical model building.