Statistical Learning
On maximum-likelihood estimation in the all-or-nothing regime
Corinzia, Luca, Penna, Paolo, Szpankowski, Wojciech, Buhmann, Joachim M.
We study the problem of estimating a rank-1 additive deformation of a Gaussian tensor according to the \emph{maximum-likelihood estimator} (MLE). The analysis is carried out in the sparse setting, where the underlying signal has a support that scales sublinearly with the total number of dimensions. We show that for Bernoulli distributed signals, the MLE undergoes an \emph{all-or-nothing} (AoN) phase transition, already established for the minimum mean-square-error estimator (MMSE) in the same problem. The result follows from two main technical points: (i) the connection established between the MLE and the MMSE, using the first and second-moment methods in the constrained signal space, (ii) a recovery regime for the MMSE stricter than the simple error vanishing characterization given in the standard AoN, that is here proved as a general result.
Turn Photos into Cartoons Using Python
To create a cartoon effect, we need to pay attention to two things; edge and color palette. Those are what make the differences between a photo and a cartoon. Before jumping to the main steps, don't forget to import the required libraries in your notebook, especially cv2 and NumPy. The first main step is loading the image. Define the read_file function, which includes the cv2_imshow to load our selected image in Google Colab.
NeurT-FDR: Controlling FDR by Incorporating Feature Hierarchy
Qiu, Lin, Murrugarra-Llerena, Nils, Silva, Vítor, Lin, Lin, Chinchilli, Vernon M.
Controlling false discovery rate (FDR) while leveraging the side information of multiple hypothesis testing is an emerging research topic in modern data science. Existing methods rely on the test-level covariates while ignoring possible hierarchy among the covariates. This strategy may not be optimal for complex large-scale problems, where hierarchical information often exists among those test-level covariates. We propose NeurT-FDR which boosts statistical power and controls FDR for multiple hypothesis testing while leveraging the hierarchy among test-level covariates. Our method parametrizes the test-level covariates as a neural network and adjusts the feature hierarchy through a regression framework, which enables flexible handling of high-dimensional features as well as efficient end-to-end optimization. We show that NeurT-FDR has strong FDR guarantees and makes substantially more discoveries in synthetic and real datasets compared to competitive baselines.
Numerical issues in maximum likelihood parameter estimation for Gaussian process regression
Basak, Subhasish, Petit, Sébastien, Bect, Julien, Vazquez, Emmanuel
This article focuses on numerical issues in maximum likelihood parameter estimation for Gaussian process regression (GPR). This article investigates the origin of the numerical issues and provides simple but effective improvement strategies. This work targets a basic problem but a host of studies, particularly in the literature of Bayesian optimization, rely on off-the-shelf GPR implementations. For the conclusions of these studies to be reliable and reproducible, robust GPR implementations are critical.
Knowledge Grounded Conversational Symptom Detection with Graph Memory Networks
Luo, Hongyin, Li, Shang-Wen, Glass, James
In this work, we propose a novel goal-oriented dialog task, automatic symptom detection. We build a system that can interact with patients through dialog to detect and collect clinical symptoms automatically, which can save a doctor's time interviewing the patient. Given a set of explicit symptoms provided by the patient to initiate a dialog for diagnosing, the system is trained to collect implicit symptoms by asking questions, in order to collect more information for making an accurate diagnosis. After getting the reply from the patient for each question, the system also decides whether current information is enough for a human doctor to make a diagnosis. To achieve this goal, we propose two neural models and a training pipeline for the multi-step reasoning task. We also build a knowledge graph as additional inputs to further improve model performance. Experiments show that our model significantly outperforms the baseline by 4%, discovering 67% of implicit symptoms on average with a limited number of questions.
Medical Information Retrieval and Interpretation: A Question-Answer based Interaction Model
Sinhababu, Nilanjan, Saxena, Rahul, Sarma, Monalisa, Samanta, Debasis
The Internet has become a very powerful platform where diverse medical information are expressed daily. Recently, a huge growth is seen in searches like symptoms, diseases, medicines, and many other health related queries around the globe. The search engines typically populate the result by using the single query provided by the user and hence reaching to the final result may require a lot of manual filtering from the user's end. Current search engines and recommendation systems still lack real time interactions that may provide more precise result generation. This paper proposes an intelligent and interactive system tied up with the vast medical big data repository on the web and illustrates its potential in finding medical information.
Explanation as a Defense of Recommendation
Yang, Aobo, Wang, Nan, Deng, Hongbo, Wang, Hongning
Textual explanations have proved to help improve user satisfaction on machine-made recommendations. However, current mainstream solutions loosely connect the learning of explanation with the learning of recommendation: for example, they are often separately modeled as rating prediction and content generation tasks. In this work, we propose to strengthen their connection by enforcing the idea of sentiment alignment between a recommendation and its corresponding explanation. At training time, the two learning tasks are joined by a latent sentiment vector, which is encoded by the recommendation module and used to make word choices for explanation generation. At both training and inference time, the explanation module is required to generate explanation text that matches sentiment predicted by the recommendation module. Extensive experiments demonstrate our solution outperforms a rich set of baselines in both recommendation and explanation tasks, especially on the improved quality of its generated explanations. More importantly, our user studies confirm our generated explanations help users better recognize the differences between recommended items and understand why an item is recommended.
Show or Suppress? Managing Input Uncertainty in Machine Learning Model Explanations
Wang, Danding, Zhang, Wencan, Lim, Brian Y.
Feature attribution is widely used in interpretable machine learning to explain how influential each measured input feature value is for an output inference. However, measurements can be uncertain, and it is unclear how the awareness of input uncertainty can affect the trust in explanations. We propose and study two approaches to help users to manage their perception of uncertainty in a model explanation: 1) transparently show uncertainty in feature attributions to allow users to reflect on, and 2) suppress attribution to features with uncertain measurements and shift attribution to other features by regularizing with an uncertainty penalty. Through simulation experiments, qualitative interviews, and quantitative user evaluations, we identified the benefits of moderately suppressing attribution uncertainty, and concerns regarding showing attribution uncertainty. This work adds to the understanding of handling and communicating uncertainty for model interpretability.
Unsupervised clustering of series using dynamic programming
Sinnathamby, Karthigan, Hou, Chang-Yu, Venkataramanan, Lalitha, Gkortsas, Vasileios-Marios, Fleuret, François
Unsupervised clustering is a branch of machine learning that aims to categorize the data based on the self-similarity. In other word, data-points in the same group (called a cluster) are more similar to each other than to those in other groups. This task can be achieved by various algorithms (the well-known K-means or spectral clustering but also hierarchical clustering [1] or density-based clustering [2]) that differ significantly in their understanding of what constitutes a cluster and how to efficiently find them. In many cases, there exist models/functions, governed by a finite set of parameters, providing either physics or phenomenology correlations between input data. The presence of these models can in principle be used to characterize clusters (cluster characterization) because one can define a loss function to measure how well a point belongs to this cluster (cluster affiliation).
On the Proof of Global Convergence of Gradient Descent for Deep ReLU Networks with Linear Widths
This paper studies the global convergence of gradient descent for deep ReLU networks under the square loss. For this setting, the current state-of-the-art results show that gradient descent converges to a global optimum if the widths of all the hidden layers scale at least as $\Omega(N^8)$ ($N$ being the number of training samples). In this paper, we discuss a simple proof framework which allows us to improve the existing over-parameterization condition to linear, quadratic and cubic widths (depending on the type of initialization scheme and/or the depth of the network).