South America
Bandit Learning in Concave N-Person Games
Bravo, Mario, Leslie, David, Mertikopoulos, Panayotis
This paper examines the long-run behavior of learning with bandit feedback in non-cooperative concave games. The bandit framework accounts for extremely low-information environments where the agents may not even know they are playing a game; as such, the agents’ most sensible choice in this setting would be to employ a no-regret learning algorithm. In general, this does not mean that the players' behavior stabilizes in the long run: no-regret learning may lead to cycles, even with perfect gradient information. However, if a standard monotonicity condition is satisfied, our analysis shows that no-regret learning based on mirror descent with bandit feedback converges to Nash equilibrium with probability 1. We also derive an upper bound for the convergence rate of the process that nearly matches the best attainable rate for single-agent bandit stochastic optimization.
Algorithmic Linearly Constrained Gaussian Processes
We algorithmically construct multi-output Gaussian process priors which satisfy linear differential equations. Our approach attempts to parametrize all solutions of the equations using Gröbner bases. If successful, a push forward Gaussian process along the paramerization is the desired prior. We consider several examples from physics, geomathmatics and control, among them the full inhomogeneous system of Maxwell's equations. By bringing together stochastic learning and computeralgebra in a novel way, we combine noisy observations with precise algebraic computations.
MetaReg: Towards Domain Generalization using Meta-Regularization
Balaji, Yogesh, Sankaranarayanan, Swami, Chellappa, Rama
Training models that generalize to new domains at test time is a problem of fundamental importance in machine learning. In this work, we encode this notion of domain generalization using a novel regularization function. We pose the problem of finding such a regularization function in a Learning to Learn (or) meta-learning framework. The objective of domain generalization is explicitly modeled by learning a regularizer that makes the model trained on one domain to perform well on another domain. Experimental validations on computer vision and natural language datasets indicate that our method can learn regularizers that achieve good cross-domain generalization.
Unary and Binary Classification Approaches and their Implications for Authorship Verification
Halvani, Oren, Winter, Christian, Graner, Lukas
Retrieving indexed documents, not by their topical content but their writing style opens the door for a number of applications in information retrieval (IR). One application is to retrieve textual content of a certain author X, where the queried IR system is provided beforehand with a set of reference texts of X. Authorship verification (AV), which is a research subject in the field of digital text forensics, is suitable for this purpose. The task of AV is to determine if two documents (i.e. an indexed and a reference document) have been written by the same author X. Even though AV represents a unary classification problem, a number of existing approaches consider it as a binary classification task. However, the underlying classification model of an AV method has a number of serious implications regarding its prerequisites, evaluability, and applicability. In our comprehensive literature review, we observed several misunderstandings regarding the differentiation of unary and binary AV approaches that require consideration. The objective of this paper is, therefore, to clarify these by proposing clear criteria and new properties that aim to improve the characterization of existing and future AV approaches. Given both, we investigate the applicability of eleven existing unary and binary AV methods as well as four generic unary classification algorithms on two self-compiled corpora. Furthermore, we highlight an important issue concerning the evaluation of AV methods based on fixed decision criterions, which has not been paid attention in previous AV studies.
Forward Modeling for Partial Observation Strategy Games - A StarCraft Defogger
Synnaeve, Gabriel, Lin, Zeming, Gehring, Jonas, Gant, Dan, Mella, Vegard, Khalidov, Vasil, Carion, Nicolas, Usunier, Nicolas
We formulate the problem of defogging as state estimation and future state prediction from previous, partial observations in the context of real-time strategy games. We propose to employ encoder-decoder neural networks for this task, and introduce proxy tasks and baselines for evaluation to assess their ability of capturing basic game rules and high-level dynamics. By combining convolutional neural networks and recurrent networks, we exploit spatial and sequential correlations and train well-performing models on a large dataset of human games of StarCraft: Brood War. Finally, we demonstrate the relevance of our models to downstream tasks by applying them for enemy unit prediction in a state-of-the-art, rule-based StarCraft bot. We observe improvements in win rates against several strong community bots.
A shortest-path based clustering algorithm for joint human-machine analysis of complex datasets
Pizzagalli, Diego Ulisse, Gonzalez, Santiago Fernandez, Krause, Rolf
Clustering is a technique for the analysis of datasets obtained by empirical studies in several disciplines with a major application for biomedical research. Essentially, clustering algorithms are executed by machines aiming at finding groups of related points in a dataset. However, the result of grouping depends on both metrics for point-to-point similarity and rules for point-to-group association. Indeed, non-appropriate metrics and rules can lead to undesirable clustering artifacts. This is especially relevant for datasets, where groups with heterogeneous structures co-exist. In this work, we propose an algorithm that achieves clustering by exploring the paths between points. This allows both, to evaluate the properties of the path (such as gaps, density variations, etc.), and expressing the preference for certain paths. Moreover, our algorithm supports the integration of existing knowledge about admissible and non-admissible clusters by training a path classifier. We demonstrate the accuracy of the proposed method on challenging datasets including points from synthetic shapes in publicly available benchmarks and microscopy data.
2019 and beyond...what to expect from artificial intelligence
"We stand on the brink of a technological revolution that will fundamentally alter the way we live, work, and relate to one another. In its scale, scope, and complexity, the transformation will be unlike anything humankind has experienced before" As the world embarks on 2019, studies published this year by the World Economic Forum and the Inter-American Development Bank (IDB) predict that global adaptation of advanced technology will create major shifts in the labour market as soon as 2022. In fact, this year, IDB issued a news release pointing to a 2018 study on artificial intelligence (AI), urging Latin American and Caribbean governments to anticipate the consequences of AI on the job market. As it turns out, the newest turn in human evolution has birthed a collective function of humans and machines operating in the physical and virtual world, and with it, a host of concerns for humans who will have to compete with smart technology. The study, done by the Institute for the Integration of Latin America and the Caribbean (INTAL), predicts that AI could boost economies in Latin America and the Caribbean, while simultaneously offsetting job losses.
StarAlgo: A Squad Movement Planning Library for StarCraft using Monte Carlo Tree Search and Negamax
Viazovskyi, Mykyta, Certicky, Michal
Real-Time Strategy (RTS) games have recently become a popular testbed for artificial intelligence research. They represent a complex adversarial domain providing a number of interesting AI challenges. There exists a wide variety of research-supporting software tools, libraries and frameworks for one RTS game in particular -- StarCraft: Brood War. These tools are designed to address various specific sub-problems, such as resource allocation or opponent modelling so that researchers can focus exclusively on the tasks relevant to them. We present one such tool -- a library called StarAlgo that produces plans for the coordinated movement of squads (groups of combat units) within the game world. StarAlgo library can solve the squad movement planning problem using one of two algorithms: Monte Carlo Tree Search Considering Durations (MCTSCD) and a slightly modified version of Negamax. We evaluate both the algorithms, compare them, and demonstrate their usage. The library is implemented as a static C++ library that can be easily plugged into most StarCraft AI bots.
Reproducible evaluation of diffusion MRI features for automatic classification of patients with Alzheimers disease
Wen, Junhao, Samper-Gonzalez, Jorge, Bottani, Simona, Routier, Alexandre, Burgos, Ninon, Jacquemont, Thomas, Fontanella, Sabrina, Durrleman, Stanley, Epelbaum, Stephane, Bertrand, Anne, Colliot, Olivier
Diffusion MRI is the modality of choice to study alterations of white matter. In the past years, various works have used diffusion MRI for automatic classification of Alzheimers disease. However, the performances obtained with different approaches are difficult to compare because of variations in components such as input data, participant selection, image preprocessing, feature extraction, feature selection (FS) and cross-validation (CV) procedure. Moreover, these studies are also difficult to reproduce because these different components are not readily available. In a previous work (Samper-Gonzalez et al. 2018), we proposed an open-source framework for the reproducible evaluation of AD classification from T1-weighted (T1w) MRI and PET data. In the present paper, we extend this framework to diffusion MRI data. The framework comprises: tools to automatically convert ADNI data into the BIDS standard, pipelines for image preprocessing and feature extraction, baseline classifiers and a rigorous CV procedure. We demonstrate the use of the framework through assessing the influence of diffusion tensor imaging (DTI) metrics (fractional anisotropy - FA, mean diffusivity - MD), feature types, imaging modalities (diffusion MRI or T1w MRI), data imbalance and FS bias. First, voxel-wise features generally gave better performances than regional features. Secondly, FA and MD provided comparable results for voxel-wise features. Thirdly, T1w MRI performed better than diffusion MRI. Fourthly, we demonstrated that using non-nested validation of FS leads to unreliable and over-optimistic results. All the code is publicly available: general-purpose tools have been integrated into the Clinica software (www.clinica.run) and the paper-specific code is available at: https://gitlab.icm-institute.org/aramislab/AD-ML.
Get Ready. 2019 Predictions About Artificial Intelligence That Will Make Your Head Spin
A staff member stands near a computer as it participates in the CHAIN Cup at the China National Convention Center in Beijing. A computer running artificial intelligence software defeated two teams of human doctors in accurately recognizing maladies in magnetic resonance images on Saturday, in a contest that was billed as the world's first competition in neuroimaging between AI and human experts. While the hip, ubiquitous business buzzwords are cryptocurrency and blockchain, the truly formidable factor of what is being called the fourth industrial revolution is Artificial Intelligence. Whether praised as a panacea for greater business efficiency or the feared as the demise of humanity, Artificial Intelligence is upon us and will impact business and society at large in ways that we can only begin to imagine. Here's what a few influencers in the arena say is on tap for 2019. First, Ibrahim Haddad, Director of Research at The Linux Foundation says that there are two key areas to watch.