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Improving exploration in policy gradient search: Application to symbolic optimization

arXiv.org Machine Learning

Many machine learning strategies designed to automate mathematical tasks leverage neural networks to search large combinatorial spaces of mathematical symbols. In contrast to traditional evolutionary approaches, using a neural network at the core of the search allows learning higher-level symbolic patterns, providing an informed direction to guide the search. When no labeled data is available, such networks can still be trained using reinforcement learning. However, we demonstrate that this approach can suffer from an early commitment phenomenon and from initialization bias, both of which limit exploration. We present two exploration methods to tackle these issues, building upon ideas of entropy regularization and distribution initialization. We show that these techniques can improve the performance, increase sample efficiency, and lower the complexity of solutions for the task of symbolic regression.


Likelihood-Free Frequentist Inference: Bridging Classical Statistics and Machine Learning in Simulation and Uncertainty Quantification

arXiv.org Machine Learning

Many areas of science make extensive use of computer simulators that implicitly encode likelihood functions of complex systems. Classical statistical methods are poorly suited for these so-called likelihood-free inference (LFI) settings, outside the asymptotic and low-dimensional regimes. Although new machine learning methods, such as normalizing flows, have revolutionized the sample efficiency and capacity of LFI methods, it remains an open question whether they produce reliable measures of uncertainty. This paper presents a statistical framework for LFI that unifies classical statistics with modern machine learning to: (1) efficiently construct frequentist confidence sets and hypothesis tests with finite-sample guarantees of nominal coverage (type I error control) and power; (2) provide practical diagnostics for assessing empirical coverage over the entire parameter space. We refer to our framework as likelihood-free frequentist inference (LF2I). Any method that estimates a test statistic, like the likelihood ratio, can be plugged into our framework to create valid confidence sets and compute diagnostics, without costly Monte Carlo samples at fixed parameter settings. In this work, we specifically study the power of two test statistics (ACORE and BFF), which, respectively, maximize versus integrate an odds function over the parameter space. Our study offers multifaceted perspectives on the challenges in LF2I.


An Analysis of Reinforcement Learning for Malaria Control

arXiv.org Artificial Intelligence

Previous work on policy learning for Malaria control has often formulated the problem as an optimization problem assuming the objective function and the search space have a specific structure. The problem has been formulated as multi-armed bandits, contextual bandits and a Markov Decision Process in isolation. Furthermore, an emphasis is put on developing new algorithms specific to an instance of Malaria control, while ignoring a plethora of simpler and general algorithms in the literature. In this work, we formally study the formulation of Malaria control and present a comprehensive analysis of several formulations used in the literature. In addition, we implement and analyze several reinforcement learning algorithms in all formulations and compare them to black box optimization. In contrast to previous work, our results show that simple algorithms based on Upper Confidence Bounds are sufficient for learning good Malaria policies, and tend to outperform their more advanced counterparts on the malaria OpenAI Gym environment.


Futuregazing: as economies create more data, how can they manage analytics?

#artificialintelligence

But, as entire economies become more data-driven, with government-enforced tax controls demanding increasingly granular levels of transactional information, there is a growing need for analytics solutions capable of handling this data, securely and at scale. Fortunately, innovations such as artificial intelligence (AI) and machine learning mean that businesses are able to scale up their analysis like never before to ensure the right data is presented in the right format for the right audience. Tax reporting is becoming more complicated as different countries have different requirements. With increasingly strict penalties for non-compliance, businesses everywhere need to consider their analytics capabilities if they hope to keep up. In an effort to close their respective country's VAT gap, tax authorities across the world are using every tool at their disposal to collect all revenue owed to them. Real-time VAT reporting, for example, is growing in popularity, with many tax authorities employing continuous transaction controls – such as electronic invoicing and audit reporting – to insert themselves ever closer to companies' transactions.


When the Game Is Over, Where Do Our Avatars Go?

WIRED

In the 2003 Major League Baseball season, Oreo Queefs stood five-foot-zero, weighed 385 pounds, and, impossibly, stole 214 bases, obliterating the century-old single-season record of 138. A walrus with the legs of a cheetah, the purple goateed Queefs also regularly blasted the ball 500 feet to opposite field--steroid-free beefiness never seen before or since. Over just two seasons with the Florida Marlins, he batted .680, Then, before even reaching his super alien prime, Queefs vanished into thin air. A few weeks ago, I received a text from the Marlins manager about what happened to the former Golden Glove winner.


How AI Can Spot Wildfires Faster Than Humans

#artificialintelligence

I explain Artificial Intelligence terms and news to non-experts. Wildfires are more and more present in modern society, mainly caused by heat waves, lightning, droughts, climate change, or even human actions like car fires, or cigarette butts. We've seen it everywhere recently Brazil, Australia, United States, Canada, etc., destroying plant, human, and animal life, property damage, and contributing to global warming through the high amount of CO2 produced. But thanks to AI, we may be able to spot these fires much sooner and take action sooner. Here's how artificial intelligence can be used to reduce fire detection time from an average of 40 minutes to less than five minutes!


Compressed particle methods for expensive models with application in Astronomy and Remote Sensing

arXiv.org Machine Learning

In many inference problems, the evaluation of complex and costly models is often required. In this context, Bayesian methods have become very popular in several fields over the last years, in order to obtain parameter inversion, model selection or uncertainty quantification. Bayesian inference requires the approximation of complicated integrals involving (often costly) posterior distributions. Generally, this approximation is obtained by means of Monte Carlo (MC) methods. In order to reduce the computational cost of the corresponding technique, surrogate models (also called emulators) are often employed. Another alternative approach is the so-called Approximate Bayesian Computation (ABC) scheme. ABC does not require the evaluation of the costly model but the ability to simulate artificial data according to that model. Moreover, in ABC, the choice of a suitable distance between real and artificial data is also required. In this work, we introduce a novel approach where the expensive model is evaluated only in some well-chosen samples. The selection of these nodes is based on the so-called compressed Monte Carlo (CMC) scheme. We provide theoretical results supporting the novel algorithms and give empirical evidence of the performance of the proposed method in several numerical experiments. Two of them are real-world applications in astronomy and satellite remote sensing.


A Survey on Role-Oriented Network Embedding

arXiv.org Artificial Intelligence

Recently, Network Embedding (NE) has become one of the most attractive research topics in machine learning and data mining. NE approaches have achieved promising performance in various of graph mining tasks including link prediction and node clustering and classification. A wide variety of NE methods focus on the proximity of networks. They learn community-oriented embedding for each node, where the corresponding representations are similar if two nodes are closer to each other in the network. Meanwhile, there is another type of structural similarity, i.e., role-based similarity, which is usually complementary and completely different from the proximity. In order to preserve the role-based structural similarity, the problem of role-oriented NE is raised. However, compared to community-oriented NE problem, there are only a few role-oriented embedding approaches proposed recently. Although less explored, considering the importance of roles in analyzing networks and many applications that role-oriented NE can shed light on, it is necessary and timely to provide a comprehensive overview of existing role-oriented NE methods. In this review, we first clarify the differences between community-oriented and role-oriented network embedding. Afterwards, we propose a general framework for understanding role-oriented NE and a two-level categorization to better classify existing methods. Then, we select some representative methods according to the proposed categorization and briefly introduce them by discussing their motivation, development and differences. Moreover, we conduct comprehensive experiments to empirically evaluate these methods on a variety of role-related tasks including node classification and clustering (role discovery), top-k similarity search and visualization using some widely used synthetic and real-world datasets...


The rising culture of entrepreneurship

#artificialintelligence

For the last two decades, I've resided in various European countries. A common observation in all those countries is the disparity between the number of elderly people and children. In fact, only less than one-third of Europe's population is under the age of 30. However, in Pakistan, this situation is quite the opposite; around 64% of the Pakistani population is under the age of 30, and, according to the United Nations Development Program (UNDP), this situation will continue to increase until at least 2050. Thus, Pakistan is potentially sitting on a gold mine: its vibrant and dynamic youth.


Machine Learning in Finance Market Activities 2021 - Publicist Records

#artificialintelligence

This has brought along several changes in This report also covers the impact of COVID-19 on the global market. The Machine Learning in Finance Market analysis summary by Reports Insights is a thorough study of the current trends leading to this vertical trend in various regions. In addition, this study emphasizes thorough competition analysis on market prospects, especially growth strategies that market experts claim. Machine Learning in Finance Market competition by top manufacturers as follow: Ignite Ltd, Yodlee, Trill A.I., MindTitan, Accenture, ZestFinance The global Machine Learning in Finance market has been segmented on the basis of technology, product type, application, distribution channel, end-user, and industry vertical, along with the geography, delivering valuable insights. To get this report at a profitable rate.: https://www.reportsinsights.com/discount/455084