Statistical Learning
Two Heads are Better than One: Geometric-Latent Attention for Point Cloud Classification and Segmentation
Cuevas-Velasquez, Hanz, Gallego, Antonio Javier, Fisher, Robert B.
We present an innovative two-headed attention layer that combines geometric and latent features to segment a 3D scene into semantically meaningful subsets. Each head combines local and global information, using either the geometric or latent features, of a neighborhood of points and uses this information to learn better local relationships. This Geometric-Latent attention layer (Ge-Latto) is combined with a sub-sampling strategy to capture global features. Our method is invariant to permutation thanks to the use of shared-MLP layers, and it can also be used with point clouds with varying densities because the local attention layer does not depend on the neighbor order. Our proposal is simple yet robust, which allows it to achieve competitive results in the ShapeNetPart and ModelNet40 datasets, and the state-of-the-art when segmenting the complex dataset S3DIS, with 69.2% IoU on Area 5, and 89.7% overall accuracy using K-fold cross-validation on the 6 areas.
Conical Classification For Computationally Efficient One-Class Topic Determination
As the Internet grows in size, so does the amount of text based information that exists. For many application spaces it is paramount to isolate and identify texts that relate to a particular topic. While one-class classification would be ideal for such analysis, there is a relative lack of research regarding efficient approaches with high predictive power. By noting that the range of documents we wish to identify can be represented as positive linear combinations of the Vector Space Model representing our text, we propose Conical classification, an approach that allows us to identify if a document is of a particular topic in a computationally efficient manner. We also propose Normal Exclusion, a modified version of Bi-Normal Separation that makes it more suitable within the one-class classification context. We show in our analysis that our approach not only has higher predictive power on our datasets, but is also faster to compute.
A Survey on the Robustness of Feature Importance and Counterfactual Explanations
Mishra, Saumitra, Dutta, Sanghamitra, Long, Jason, Magazzeni, Daniele
There exist several methods that aim to address the crucial task of understanding the behaviour of AI/ML models. Arguably, the most popular among them are local explanations that focus on investigating model behaviour for individual instances. Several methods have been proposed for local analysis, but relatively lesser effort has gone into understanding if the explanations are robust and accurately reflect the behaviour of underlying models. In this work, we present a survey of the works that analysed the robustness of two classes of local explanations (feature importance and counterfactual explanations) that are popularly used in analysing AI/ML models in finance. The survey aims to unify existing definitions of robustness, introduces a taxonomy to classify different robustness approaches, and discusses some interesting results. Finally, the survey introduces some pointers about extending current robustness analysis approaches so as to identify reliable explainability methods.
3DP3: 3D Scene Perception via Probabilistic Programming
Gothoskar, Nishad, Cusumano-Towner, Marco, Zinberg, Ben, Ghavamizadeh, Matin, Pollok, Falk, Garrett, Austin, Tenenbaum, Joshua B., Gutfreund, Dan, Mansinghka, Vikash K.
We present 3DP3, a framework for inverse graphics that uses inference in a structured generative model of objects, scenes, and images. 3DP3 uses (i) voxel models to represent the 3D shape of objects, (ii) hierarchical scene graphs to decompose scenes into objects and the contacts between them, and (iii) depth image likelihoods based on real-time graphics. Given an observed RGB-D image, 3DP3's inference algorithm infers the underlying latent 3D scene, including the object poses and a parsimonious joint parametrization of these poses, using fast bottom-up pose proposals, novel involutive MCMC updates of the scene graph structure, and, optionally, neural object detectors and pose estimators. We show that 3DP3 enables scene understanding that is aware of 3D shape, occlusion, and contact structure. Our results demonstrate that 3DP3 is more accurate at 6DoF object pose estimation from real images than deep learning baselines and shows better generalization to challenging scenes with novel viewpoints, contact, and partial observability.
A Comparative Review of Recent Few-Shot Object Detection Algorithms
Jiaxu, Leng, Taiyue, Chen, Xinbo, Gao, Yongtao, Yu, Ye, Wang, Feng, Gao, Yue, Wang
Few-shot object detection, learning to adapt to the novel classes with a few labeled data, is an imperative and long-lasting problem due to the inherent long-tail distribution of real-world data and the urgent demands to cut costs of data collection and annotation. Recently, some studies have explored how to use implicit cues in extra datasets without target-domain supervision to help few-shot detectors refine robust task notions. This survey provides a comprehensive overview from current classic and latest achievements for few-shot object detection to future research expectations from manifold perspectives. In particular, we first propose a data-based taxonomy of the training data and the form of corresponding supervision which are accessed during the training stage. Following this taxonomy, we present a significant review of the formal definition, main challenges, benchmark datasets, evaluation metrics, and learning strategies. In addition, we present a detailed investigation of how to interplay the object detection methods to develop this issue systematically. Finally, we conclude with the current status of few-shot object detection, along with potential research directions for this field.
Language: Dogs pick up on individual words in a similar way to human babies, study finds
Dogs are able to pick up on individual words in sentences spoken to them using similar computations and brain regions as human babies, a study has found. When we are infants, we learn to spot new words in a stream of speech first, before we actually learn what each individual word means. To tell where each word ends and another begins, babies use complex calculations that keep track of which syllables appear together -- and thus likely form words. By using a combination of brain imaging techniques, experts led from Hungary's Eรถtvรถs Lorรกnd University have shown that dogs are capable of similar feats. This is the first time that the capacity to apply so-called statistical learning has been shown to be demonstrated in a non-human mammal.
What is regression Analysis
Regression analysis is likely the first predictive modeling method you learned as a practitioner during your academic studies or the most common modeling method for your analytics group. Regression concepts were first published in the early 1800s by AdrienโMarie Legrendre and Carl Gauss. Legrendre was born into a wealthy French family and contributed to a number of advances in the fi elds of mathematics and statistics. Gauss, in contrast, was born to a poor family in Germany. Gauss was a child math prodigy but throughout his life he was reluctant to publish any work that he felt was not above criticism.
Three common problems on supervised learning
A: They are almost identical. Linear Regression uses Ordinary least squares (OLS) to get an unbiased and high variance solution. Things like multi-collinearity can cause Linear Regression to fail. Ridge Regression is solved pretty much the same way, but it adds a regularization constant. The constant is a source of bias and can decrease variance.
Machine Learning A-Z : Hands-On Python & R In Data Science
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Data-driven Uncertainty Quantification in Computational Human Head Models
Upadhyay, Kshitiz, Giovanis, Dimitris G., Alshareef, Ahmed, Knutsen, Andrew K., Johnson, Curtis L., Carass, Aaron, Bayly, Philip V., Shields, Michael D., Ramesh, K. T.
Computational models of the human head are promising tools for estimating the impact-induced response of brain, and thus play an important role in the prediction of traumatic brain injury. Modern biofidelic head model simulations are associated with very high computational cost, and high-dimensional inputs and outputs, which limits the applicability of traditional uncertainty quantification (UQ) methods on these systems. In this study, a two-stage, data-driven manifold learning-based framework is proposed for UQ of computational head models. This framework is demonstrated on a 2D subject-specific head model, where the goal is to quantify uncertainty in the simulated strain fields (i.e., output), given variability in the material properties of different brain substructures (i.e., input). In the first stage, a data-driven method based on multi-dimensional Gaussian kernel-density estimation and diffusion maps is used to generate realizations of the input random vector directly from the available data. Computational simulations of a small number of realizations provide input-output pairs for training data-driven surrogate models in the second stage. The surrogate models employ nonlinear dimensionality reduction using Grassmannian diffusion maps, Gaussian process regression to create a low-cost mapping between the input random vector and the reduced solution space, and geometric harmonics models for mapping between the reduced space and the Grassmann manifold. It is demonstrated that the surrogate models provide highly accurate approximations of the computational model while significantly reducing the computational cost. Monte Carlo simulations of the surrogate models are used for uncertainty propagation. UQ of strain fields highlight significant spatial variation in model uncertainty, and reveal key differences in uncertainty among commonly used strain-based brain injury predictor variables.