Statistical Learning
S-LIME: Stabilized-LIME for Model Explanation
Zhou, Zhengze, Hooker, Giles, Wang, Fei
An increasing number of machine learning models have been deployed in domains with high stakes such as finance and healthcare. Despite their superior performances, many models are black boxes in nature which are hard to explain. There are growing efforts for researchers to develop methods to interpret these black-box models. Post hoc explanations based on perturbations, such as LIME, are widely used approaches to interpret a machine learning model after it has been built. This class of methods has been shown to exhibit large instability, posing serious challenges to the effectiveness of the method itself and harming user trust. In this paper, we propose S-LIME, which utilizes a hypothesis testing framework based on central limit theorem for determining the number of perturbation points needed to guarantee stability of the resulting explanation. Experiments on both simulated and real world data sets are provided to demonstrate the effectiveness of our method.
Time Series Analysis Real World Projects in Python
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Conference proceedings KI4Industry AI for SMEs -- the online congress for practical entry into AI for SMEs
Feiner, Matthias, Schoellhorn, Manuel
The Institute of Materials and Processes, IMP, of the University of Applied Sciences in Karlsruhe, Germany in cooperation with VDI Verein Deutscher Ingenieure e.V, AEN Automotive Engineering Network and their cooperation partners present their competences of AI-based solution approaches in the production engineering field. The online congress KI 4 Industry on November 12 and 13, 2020, showed what opportunities the use of artificial intelligence offers for medium-sized manufacturing companies, SMEs, and where potential fields of application lie. The main purpose of KI 4 Industry is to increase the transfer of knowledge, research and technology from universities to small and medium-sized enterprises, to demystify the term AI and to encourage companies to use AI-based solutions in their own value chain or in their products.
Few-Shot Learning with Class Imbalance
Ochal, Mateusz, Patacchiola, Massimiliano, Storkey, Amos, Vazquez, Jose, Wang, Sen
Abstract--Few-Shot Learning (FSL) algorithms are commonly trained through Meta-Learning (ML), which exposes models to batches of tasks sampled from a meta-dataset to mimic tasks seen during evaluation. However, the standard training procedures overlook the real-world dynamics where classes commonly occur at different frequencies. While it is generally understood that class imbalance harms the performance of supervised methods, limited research examines the impact of imbalance on the FSL evaluation task. Our analysis compares 10 state-of-the-art meta-learning and FSL methods on different imbalance distributions and rebalancing techniques. Our results reveal that 1) some FSL methods display a natural disposition against imbalance while most other approaches produce a performance drop by up to 17% compared to the balanced task without the appropriate mitigation; 2) contrary to popular belief, many meta-learning algorithms will not automatically learn to balance from exposure to imbalanced training tasks; 3) classical rebalancing strategies, such as random oversampling, can still be very effective, leading to state-of-the-art performances and should not be overlooked; 4) FSL methods are more robust against meta-dataset imbalance than imbalance at the task-level with a similar imbalance ratio ( ρ < 20), with the effect holding even in long-tail datasets under a larger imbalance ( ρ = 65). We identify well to new examples. However, large datasets can be costly and examine three levels of class imbalance: task-level, to obtain and annotate [1]. This is a particularly limiting dataset-level, and combined (task-level and dataset-level) issue in many real-world situations due to the need to perform imbalance. In contrast to previous work on CIFSL [12], [13], real-time operations, the presence of rare categories, [14], [15], we explicitly attribute and quantify the impact on or the desire for a good user experience [2], [3], [4], [5]. the performance caused by class imbalance for each model. Few-Shot Learning (FSL) alleviates this burden by defining Moreover, we study multiple class imbalance distributions, a distribution over tasks, with each task containing a few giving a realistic assessment of performance and revealing labeled data points (support set) and a set of target data previously unknown strengths and weaknesses of 10 stateof-the-art (query set) belonging to the same set of classes. Additionally, we offer practical advice, way to train FSL methods is through Meta-Learning (ML). Figure 1 the model is repeatedly exposed to batches of tasks sampled shows a graphical representation of the CIFSL problem.
Fair Sparse Regression with Clustering: An Invex Relaxation for a Combinatorial Problem
In this paper, we study the problem of fair sparse regression on a biased dataset where bias depends upon a hidden binary attribute. The presence of a hidden attribute adds an extra layer of complexity to the problem by combining sparse regression and clustering with unknown binary labels. The corresponding optimization problem is combinatorial, but we propose a novel relaxation of it as an \emph{invex} optimization problem. To the best of our knowledge, this is the first invex relaxation for a combinatorial problem. We show that the inclusion of the debiasing/fairness constraint in our model has no adverse effect on the performance. Rather, it enables the recovery of the hidden attribute. The support of our recovered regression parameter vector matches exactly with the true parameter vector. Moreover, we simultaneously solve the clustering problem by recovering the exact value of the hidden attribute for each sample. Our method uses carefully constructed primal dual witnesses to provide theoretical guarantees for the combinatorial problem. To that end, we show that the sample complexity of our method is logarithmic in terms of the dimension of the regression parameter vector.
Node Classification Meets Link Prediction on Knowledge Graphs
Abboud, Ralph, Ceylan, İsmail İlkan
Node classification and link prediction are widely studied tasks in graph representation learning. While both transductive node classification and link prediction operate over a single input graph, they are studied in isolation so far, which leads to discrepancies. Node classification models take as input a graph with node features and incomplete node labels, and implicitly assume that the input graph is relationally complete, i.e., no edges are missing from the input graph. This is in sharp contrast with link prediction models that are solely motivated by the relational incompleteness of the input graph which does not have any node features. We propose a unifying perspective and study the problems of (i) transductive node classification over incomplete graphs and (ii) link prediction over graphs with node features. We propose an extension to an existing box embedding model, and show that this model is fully expressive, and can solve both of these tasks in an end-to-end fashion. To empirically evaluate our model, we construct a knowledge graph with node features, which is challenging both for node classification and link prediction. Our model performs very strongly when compared to the respective state-of-the-art models for node classification and link prediction on this dataset and shows the importance of a unified perspective for node classification and link prediction on knowledge graphs.
Certification of embedded systems based on Machine Learning: A survey
Vidot, Guillaume, Gabreau, Christophe, Ober, Ileana, Ober, Iulian
Nevertheless, the recent advances in machine learning triggered genuine interest, as machine learning offer promising preliminary results and open the way to a wide range of new functions for avionics systems, for instance in the area of autonomous flying. In this paper we investigate on how existing certification and regulation techniques, can (or cannot) handle software development that includes parts obtained by machine learning. Nowadays a large aircraft cockpit offers many avionic complex functions: flight controls, navigation, surveillance, communications, displays... Their design has required a top down iterative approach from aircraft level downward, thus the functions are performed by systems of systems, with each system decomposed into subsystems that may contain a collection of software and hardware items. Therefore, any avionic development considers 3 levels of engineering: (i) Function, (ii) System/Subsystem and (iii) Item. The development process of each engineering level relies on several decades of experience and good practices that keep on being adapted today.
Outlier detection in multivariate functional data through a contaminated mixture model
Amovin-Assagba, Martial, Gannaz, Irène, Jacques, Julien
This work is motivated by an application in an industrial context, where the activity of sensors is recorded at a high frequency. The objective is to automatically detect abnormal measurement behaviour. Considering the sensor measures as functional data, we are formally interested in detecting outliers in a multivariate functional data set. Due to the heterogeneity of this data set, the proposed contaminated mixture model both clusters the multivariate functional data into homogeneous groups and detects outliers. The main advantage of this procedure over its competitors is that it does not require us to specify the proportion of outliers. Model inference is performed through an Expectation-Conditional Maximization algorithm, and the BIC criterion is used to select the number of clusters. Numerical experiments on simulated data demonstrate the high performance achieved by the inference algorithm. In particular, the proposed model outperforms competitors. Its application on the real data which motivated this study allows us to correctly detect abnormal behaviours.
HuBERT: Self-Supervised Speech Representation Learning by Masked Prediction of Hidden Units
Hsu, Wei-Ning, Bolte, Benjamin, Tsai, Yao-Hung Hubert, Lakhotia, Kushal, Salakhutdinov, Ruslan, Mohamed, Abdelrahman
Self-supervised approaches for speech representation learning are challenged by three unique problems: (1) there are multiple sound units in each input utterance, (2) there is no lexicon of input sound units during the pre-training phase, and (3) sound units have variable lengths with no explicit segmentation. To deal with these three problems, we propose the Hidden-Unit BERT (HuBERT) approach for self-supervised speech representation learning, which utilizes an offline clustering step to provide aligned target labels for a BERT-like prediction loss. A key ingredient of our approach is applying the prediction loss over the masked regions only, which forces the model to learn a combined acoustic and language model over the continuous inputs. HuBERT relies primarily on the consistency of the unsupervised clustering step rather than the intrinsic quality of the assigned cluster labels. Starting with a simple k-means teacher of 100 clusters, and using two iterations of clustering, the HuBERT model either matches or improves upon the state-of-the-art wav2vec 2.0 performance on the Librispeech (960h) and Libri-light (60,000h) benchmarks with 10min, 1h, 10h, 100h, and 960h fine-tuning subsets. Using a 1B parameter model, HuBERT shows up to 19% and 13% relative WER reduction on the more challenging dev-other and test-other evaluation subsets.
Bandit Modeling of Map Selection in Counter-Strike: Global Offensive
Petri, Guido, Stanley, Michael H., Hon, Alec B., Dong, Alexander, Xenopoulos, Peter, Silva, Cláudio
Many esports use a pick and ban process to define the parameters of a match before it starts. In Counter-Strike: Global Offensive (CSGO) matches, two teams first pick and ban maps, or virtual worlds, to play. Teams typically ban and pick maps based on a variety of factors, such as banning maps which they do not practice, or choosing maps based on the team's recent performance. We introduce a contextual bandit framework to tackle the problem of map selection in CSGO and to investigate teams' pick and ban decision-making. Using a data set of over 3,500 CSGO matches and over 25,000 map selection decisions, we consider different framings for the problem, different contexts, and different reward metrics. We find that teams have suboptimal map choice policies with respect to both picking and banning. We also define an approach for rewarding bans, which has not been explored in the bandit setting, and find that incorporating ban rewards improves model performance. Finally, we determine that usage of our model could improve teams' predicted map win probability by up to 11% and raise overall match win probabilities by 19.8% for evenly-matched teams.