Goto

Collaborating Authors

 Statistical Learning


Learning to Plan via a Multi-Step Policy Regression Method

arXiv.org Artificial Intelligence

We propose a new approach to increase inference performance in environments that require a specific sequence of actions in order to be solved. This is for example the case for maze environments where ideally an optimal path is determined. Instead of learning a policy for a single step, we want to learn a policy that can predict n actions in advance. Our proposed method called policy horizon regression (PHR) uses knowledge of the environment sampled by A2C to learn an n dimensional policy vector in a policy distillation setup which yields n sequential actions per observation. We test our method on the MiniGrid and Pong environments and show drastic speedup during inference time by successfully predicting sequences of actions on a single observation.


On the Connections between Counterfactual Explanations and Adversarial Examples

arXiv.org Artificial Intelligence

Counterfactual explanations and adversarial examples have emerged as critical research areas for addressing the explainability and robustness goals of machine learning (ML). While counterfactual explanations were developed with the goal of providing recourse to individuals adversely impacted by algorithmic decisions, adversarial examples were designed to expose the vulnerabilities of ML models. While prior research has hinted at the commonalities between these frameworks, there has been little to no work on systematically exploring the connections between the literature on counterfactual explanations and adversarial examples. In this work, we make one of the first attempts at formalizing the connections between counterfactual explanations and adversarial examples. More specifically, we theoretically analyze salient counterfactual explanation and adversarial example generation methods, and highlight the conditions under which they behave similarly. Our analysis demonstrates that several popular counterfactual explanation and adversarial example generation methods such as the ones proposed by Wachter et. al. and Carlini and Wagner (with mean squared error loss), and C-CHVAE and natural adversarial examples by Zhao et. al. are equivalent. We also bound the distance between counterfactual explanations and adversarial examples generated by Wachter et. al. and DeepFool methods for linear models. Finally, we empirically validate our theoretical findings using extensive experimentation with synthetic and real world datasets.


Embedding Heterogeneous Networks into Hyperbolic Space Without Meta-path

arXiv.org Artificial Intelligence

Networks found in the real-world are numerous and varied. A common type of network is the heterogeneous network, where the nodes (and edges) can be of different types. Accordingly, there have been efforts at learning representations of these heterogeneous networks in low-dimensional space. However, most of the existing heterogeneous network embedding methods suffer from the following two drawbacks: (1) The target space is usually Euclidean. Conversely, many recent works have shown that complex networks may have hyperbolic latent anatomy, which is non-Euclidean. (2) These methods usually rely on meta-paths, which require domain-specific prior knowledge for meta-path selection. Additionally, different down-streaming tasks on the same network might require different meta-paths in order to generate task-specific embeddings. In this paper, we propose a novel self-guided random walk method that does not require meta-path for embedding heterogeneous networks into hyperbolic space. We conduct thorough experiments for the tasks of network reconstruction and link prediction on two public datasets, showing that our model outperforms a variety of well-known baselines across all tasks.


Being Properly Improper

arXiv.org Artificial Intelligence

In today's ML, data can be twisted (changed) in various ways, either for bad or good intent. Such twisted data challenges the founding theory of properness for supervised losses which form the basis for many popular losses for class probability estimation. Unfortunately, at its core, properness ensures that the optimal models also learn the twist. In this paper, we analyse such class probability-based losses when they are stripped off the mandatory properness; we define twist-proper losses as losses formally able to retrieve the optimum (untwisted) estimate off the twists, and show that a natural extension of a half-century old loss introduced by S. Arimoto is twist proper. We then turn to a theory that has provided some of the best off-the-shelf algorithms for proper losses, boosting. Boosting can require access to the derivative of the convex conjugate of a loss to compute examples weights. Such a function can be hard to get, for computational or mathematical reasons; this turns out to be the case for Arimoto's loss. We bypass this difficulty by inverting the problem as follows: suppose a blueprint boosting algorithm is implemented with a general weight update function. What are the losses for which boosting-compliant minimisation happens? Our answer comes as a general boosting algorithm which meets the optimal boosting dependence on the number of calls to the weak learner; when applied to Arimoto's loss, it leads to a simple optimisation algorithm whose performances are showcased on several domains and twists.


Message Passing in Graph Convolution Networks via Adaptive Filter Banks

arXiv.org Artificial Intelligence

Graph convolution networks, like message passing graph convolution networks (MPGCNs), have been a powerful tool in representation learning of networked data. However, when data is heterogeneous, most architectures are limited as they employ a single strategy to handle multi-channel graph signals and they typically focus on low-frequency information. In this paper, we present a novel graph convolution operator, termed BankGCN, which keeps benefits of message passing models, but extends their capabilities beyond `low-pass' features. It decomposes multi-channel signals on graphs into subspaces and handles particular information in each subspace with an adapted filter. The filters of all subspaces have different frequency responses and together form a filter bank. Furthermore, each filter in the spectral domain corresponds to a message passing scheme, and diverse schemes are implemented via the filter bank. Importantly, the filter bank and the signal decomposition are jointly learned to adapt to the spectral characteristics of data and to target applications. Furthermore, this is implemented almost without extra parameters in comparison with most existing MPGCNs. Experimental results show that the proposed convolution operator permits to achieve excellent performance in graph classification on a collection of benchmark graph datasets.


Top 10 Must-Know Machine Learning Algorithms for Data Scientists โ€“ Part 1 - KDnuggets

#artificialintelligence

Wading through the vast array of information for data science newcomers on machine learning algorithms can be a difficult and time-consuming process. Figuring out which algorithms are widely used and which are simply novel or interesting is not just an academic exercise; determining where to concentrate your time and focus during the early days of study can determine the difference between getting your career off to a quick start and experiencing an extended ground delay. How, exactly, does one discriminate between immediately useful algorithms worthy of attention and, well, not so much? Determining how to come up with an objective list of machine learning algorithms of authority is inherently difficult, but it seems that going directly to practitioners for their feedback may be the optimal approach. Such a process presents a whole host of difficulties of its own, as could be easily imagined, and results of such surveys are few and far between.


Build XGBoost models with Amazon Redshift ML

#artificialintelligence

Amazon Redshift ML allows data analysts, developers, and data scientists to train machine learning (ML) models using SQL. In previous posts, we demonstrated how customers can use the automatic model training capability of Amazon Redshift to train their classification and regression models. Redshift ML provides several capabilities for data scientists. It allows you to create a model using SQL and specify your algorithm as XGBoost. It also lets you bring your pre-trained XGBoost model into Amazon Redshift for local inference.


Kruskal Wallis test in R-One-way ANOVA Alternative

#artificialintelligence

Kruskal Wallis test in R, Kruskal Wallis test is one of the frequently used methods in nonparametric statistics for analyzing data in one-way classification. It is equivalent to a one-way analysis of variance in parametric methods. When we test the identicalness of the k population from which the independent samples have been drawn. There is no restriction of sample sizes. Mainly Kruskal Wallis test is based on the following assumptions.


Introducing Modeltime: Tidy Time Series Forecasting using Tidymodels

#artificialintelligence

I'm beyond excited to introduce modeltime, a new time series forecasting package designed to speed up model evaluation, selection, and forecasting. Follow the updated modeltime article to get started with modeltime. If you like what you see, I have an Advanced Time Series Course where you will become the time-series expert for your organization by learning modeltime and timetk. This article is part of a series of software announcements on the Modeltime Forecasting Ecosystem. Register to stay in the know on new cutting-edge R software like modeltime.


Complete Machine Learning & Data Science with Python

#artificialintelligence

Machine learning is constantly being applied to new industries and new problems. Whether you're a marketer, video game designer, or programmer, my course on Udemy here to help you apply machine learning to your work. Welcome to the "Complete Machine Learning & Data Science with Python A-Z" course. Do you know data science needs will create 11.5 million job openings by 2026? Do you know the average salary is $100.000 for data science careers!