Overview
AUC Maximization in the Era of Big Data and AI: A Survey
Area under the ROC curve, a.k.a. AUC, is a measure of choice for assessing the performance of a classifier for imbalanced data. AUC maximization refers to a learning paradigm that learns a predictive model by directly maximizing its AUC score. It has been studied for more than two decades dating back to late 90s and a huge amount of work has been devoted to AUC maximization since then. Recently, stochastic AUC maximization for big data and deep AUC maximization for deep learning have received increasing attention and yielded dramatic impact for solving real-world problems. However, to the best our knowledge there is no comprehensive survey of related works for AUC maximization. This paper aims to address the gap by reviewing the literature in the past two decades. We not only give a holistic view of the literature but also present detailed explanations and comparisons of different papers from formulations to algorithms and theoretical guarantees. We also identify and discuss remaining and emerging issues for deep AUC maximization, and provide suggestions on topics for future work.
Efficiently Computing Nash Equilibria in Adversarial Team Markov Games
Kalogiannis, Fivos, Anagnostides, Ioannis, Panageas, Ioannis, Vlatakis-Gkaragkounis, Emmanouil-Vasileios, Chatziafratis, Vaggos, Stavroulakis, Stelios
Computing Nash equilibrium policies is a central problem in multi-agent reinforcement learning that has received extensive attention both in theory and in practice. However, provable guarantees have been thus far either limited to fully competitive or cooperative scenarios or impose strong assumptions that are difficult to meet in most practical applications. In this work, we depart from those prior results by investigating infinite-horizon \emph{adversarial team Markov games}, a natural and well-motivated class of games in which a team of identically-interested players -- in the absence of any explicit coordination or communication -- is competing against an adversarial player. This setting allows for a unifying treatment of zero-sum Markov games and Markov potential games, and serves as a step to model more realistic strategic interactions that feature both competing and cooperative interests. Our main contribution is the first algorithm for computing stationary $\epsilon$-approximate Nash equilibria in adversarial team Markov games with computational complexity that is polynomial in all the natural parameters of the game, as well as $1/\epsilon$. The proposed algorithm is particularly natural and practical, and it is based on performing independent policy gradient steps for each player in the team, in tandem with best responses from the side of the adversary; in turn, the policy for the adversary is then obtained by solving a carefully constructed linear program. Our analysis leverages non-standard techniques to establish the KKT optimality conditions for a nonlinear program with nonconvex constraints, thereby leading to a natural interpretation of the induced Lagrange multipliers. Along the way, we significantly extend an important characterization of optimal policies in adversarial (normal-form) team games due to Von Stengel and Koller (GEB `97).
20 years of network community detection
Fortunato, Santo, Newman, M. E. J.
A fundamental technical challenge in the analysis of network data is the automated discovery of communities -- groups of nodes that are strongly connected or that share similar features or roles. In this commentary we review progress in the field over the last 20 years. Community detection is a rich and challenging problem, partly because it is not very well posed: what exactly do we mean by a community? In most cases, communities are defined as non-overlapping groups of nodes such that there are more edges within groups than between them, but this definition still leaves open many possibilities, and there are correspondingly many computational approaches. The most common approaches are based on optimization.
Present and Future of SLAM in Extreme Underground Environments
Ebadi, Kamak, Bernreiter, Lukas, Biggie, Harel, Catt, Gavin, Chang, Yun, Chatterjee, Arghya, Denniston, Christopher E., Deschênes, Simon-Pierre, Harlow, Kyle, Khattak, Shehryar, Nogueira, Lucas, Palieri, Matteo, Petráček, Pavel, Petrlík, Matěj, Reinke, Andrzej, Krátký, Vít, Zhao, Shibo, Agha-mohammadi, Ali-akbar, Alexis, Kostas, Heckman, Christoffer, Khosoussi, Kasra, Kottege, Navinda, Morrell, Benjamin, Hutter, Marco, Pauling, Fred, Pomerleau, François, Saska, Martin, Scherer, Sebastian, Siegwart, Roland, Williams, Jason L., Carlone, Luca
This paper reports on the state of the art in underground SLAM by discussing different SLAM strategies and results across six teams that participated in the three-year-long SubT competition. In particular, the paper has four main goals. First, we review the algorithms, architectures, and systems adopted by the teams; particular emphasis is put on lidar-centric SLAM solutions (the go-to approach for virtually all teams in the competition), heterogeneous multi-robot operation (including both aerial and ground robots), and real-world underground operation (from the presence of obscurants to the need to handle tight computational constraints). We do not shy away from discussing the dirty details behind the different SubT SLAM systems, which are often omitted from technical papers. Second, we discuss the maturity of the field by highlighting what is possible with the current SLAM systems and what we believe is within reach with some good systems engineering. Third, we outline what we believe are fundamental open problems, that are likely to require further research to break through. Finally, we provide a list of open-source SLAM implementations and datasets that have been produced during the SubT challenge and related efforts, and constitute a useful resource for researchers and practitioners.
Smart caching in a Data Lake for High Energy Physics analysis
Tedeschi, Tommaso, Ciangottini, Diego, Baioletti, Marco, Poggioni, Valentina, Spiga, Daniele, Storchi, Loriano, Tracolli, Mirco
The continuous growth of data production in almost all scientific areas raises new problems in data access and management, especially in a scenario where the end-users, as well as the resources that they can access, are worldwide distributed. This work is focused on the data caching management in a Data Lake infrastructure in the context of the High Energy Physics field. We are proposing an autonomous method, based on Reinforcement Learning techniques, to improve the user experience and to contain the maintenance costs of the infrastructure.
No Pattern, No Recognition: a Survey about Reproducibility and Distortion Issues of Text Clustering and Topic Modeling
Silva, Marília Costa Rosendo, Siqueira, Felipe Alves, Tarrega, João Pedro Mantovani, Beinotti, João Vitor Pataca, Nunes, Augusto Sousa, Gardini, Miguel de Mattos, da Silva, Vinícius Adolfo Pereira, da Silva, Nádia Félix Felipe, de Carvalho, André Carlos Ponce de Leon Ferreira
Extracting knowledge from unlabeled texts using machine learning algorithms can be complex. Document categorization and information retrieval are two applications that may benefit from unsupervised learning (e.g., text clustering and topic modeling), including exploratory data analysis. However, the unsupervised learning paradigm poses reproducibility issues. The initialization can lead to variability depending on the machine learning algorithm. Furthermore, the distortions can be misleading when regarding cluster geometry. Amongst the causes, the presence of outliers and anomalies can be a determining factor. Despite the relevance of initialization and outlier issues for text clustering and topic modeling, the authors did not find an in-depth analysis of them. This survey provides a systematic literature review (2011-2022) of these subareas and proposes a common terminology since similar procedures have different terms. The authors describe research opportunities, trends, and open issues. The appendices summarize the theoretical background of the text vectorization, the factorization, and the clustering algorithms that are directly or indirectly related to the reviewed works.
Criticality Metrics for Automated Driving: A Review and Suitability Analysis of the State of the Art
Westhofen, Lukas, Neurohr, Christian, Koopmann, Tjark, Butz, Martin, Schütt, Barbara, Utesch, Fabian, Kramer, Birte, Gutenkunst, Christian, Böde, Eckard
The large-scale deployment of automated vehicles on public roads has the potential to vastly change the transportation modalities of today's society. Although this pursuit has been initiated decades ago, there still exist open challenges in reliably ensuring that such vehicles operate safely in open contexts. While functional safety is a well-established concept, the question of measuring the behavioral safety of a vehicle remains subject to research. One way to both objectively and computationally analyze traffic conflicts is the development and utilization of so-called criticality metrics. Contemporary approaches have leveraged the potential of criticality metrics in various applications related to automated driving, e.g. for computationally assessing the dynamic risk or filtering large data sets to build scenario catalogs. As a prerequisite to systematically choose adequate criticality metrics for such applications, we extensively review the state of the art of criticality metrics, their properties, and their applications in the context of automated driving. Based on this review, we propose a suitability analysis as a methodical tool to be used by practitioners. Both the proposed method and the state of the art review can then be harnessed to select well-suited measurement tools that cover an application's requirements, as demonstrated by an exemplary execution of the analysis. Ultimately, efficient, valid, and reliable measurements of an automated vehicle's safety performance are a key requirement for demonstrating its trustworthiness.
An Introduction to Multi-Agent Reinforcement Learning and Review of its Application to Autonomous Mobility
Schmidt, Lukas M., Brosig, Johanna, Plinge, Axel, Eskofier, Bjoern M., Mutschler, Christopher
Many scenarios in mobility and traffic involve multiple different agents that need to cooperate to find a joint solution. Recent advances in behavioral planning use Reinforcement Learning to find effective and performant behavior strategies. However, as autonomous vehicles and vehicle-to-X communications become more mature, solutions that only utilize single, independent agents leave potential performance gains on the road. Multi-Agent Reinforcement Learning (MARL) is a research field that aims to find optimal solutions for multiple agents that interact with each other. This work aims to give an overview of the field to researchers in autonomous mobility. We first explain MARL and introduce important concepts. Then, we discuss the central paradigms that underlie MARL algorithms, and give an overview of state-of-the-art methods and ideas in each paradigm. With this background, we survey applications of MARL in autonomous mobility scenarios and give an overview of existing scenarios and implementations.
The Future Of Telehealth And AI In Business
First and foremost, let us understand the meaning of "telehealth." The word'tele' means "distance" and'health' means "to heal". Telemedicine also refers to the practice of medicine at a distance whereby information technology is used to ensure the delivery of medical care services. By using mobile phones, laptops, and computers, healthcare providers and doctors can communicate with their patients virtually and write prescriptions or follow-ups. But, at the same time, with the rise of innovative technologies and the use of AI in healthcare -- healthcare businesses have taken a different shape, from traditional styles to telehealth.
C++ Developer openings in San Francisco Bay Area, United States on August 01, 2022
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