Parallel Algorithm for Approximating Nash Equilibrium in Multiplayer Stochastic Games with Application to Naval Strategic Planning Sam Ganzfried 1, Conner Laughlin 2, Charles Morefield 2 1 Ganzfried Research 2 Arctan, Inc. Abstract Many real-world domains contain multiple agents behaving strategically with probabilistic transitions and uncertain (potentially infinite) duration. Such settings can be modeled as stochastic games. While algorithms have been developed for solving (i.e., computing a game-theoretic solution concept such as Nash equilibrium) two-player zero-sum stochastic games, research on algorithms for nonzero-sum and multi-player stochastic games is very limited. We present a new algorithm for these settings, which constitutes the first parallel algorithm for multiplayer stochastic games. We present experimental results on a 4-player stochastic game motivated by a naval strategic planning scenario, showing that our algorithm is able to quickly compute strategies constituting Nash equilibrium up to a very small degree of approximation. Introduction Nash equilibrium has emerged as the most compelling solution concept in multiagent strategic interactions. For two-player zero-sum (adversarial) games, a Nash equilibrium can be computed in polynomial time (e.g., by linear programming). This result holds both for simultaneous-move games (often represented as a matrix), and for sequential games of both perfect and imperfect information (often represented as an extensive-form game tree).

This paper deals with multivariate regression chain graphs (MVR CGs), which were introduced by Cox and Wermuth [3,4] to represent linear causal models with correlated errors. We consider the PC-like algorithm for structure learning of MVR CGs, which is a constraint-based method proposed by Sonntag and Pe\~{n}a in [18]. We show that the PC-like algorithm is order-dependent, in the sense that the output can depend on the order in which the variables are given. This order-dependence is a minor issue in low-dimensional settings. However, it can be very pronounced in high-dimensional settings, where it can lead to highly variable results. We propose two modifications of the PC-like algorithm that remove part or all of this order-dependence. Simulations under a variety of settings demonstrate the competitive performance of our algorithms in comparison with the original PC-like algorithm in low-dimensional settings and improved performance in high-dimensional settings.

In this case we used the Ram-Lak filter. If the measurements are noisy, FBP reconstructions tend to include streaking artifacts. A typical approach to overcome this problem is to apply some kind of post-processing such as denoising. Recent works [9, 18, 37] have successfully used convolutional neural networks, such as the U-Net [29]. The idea is to train a neural network to create clean reconstructions out of the noisy FBP results. In our implementation we used a U-Net-like architecture which is shown in Figure 4 and is similar to the one used in [21]. There, the authors show that such an architecture is a good image prior, i.e., its output is biased towards natural images, for example, noise-free images. Training was performed by minimizing the mean squared error loss with the Adam algorithm [20] for 20 epochs with batch size 64 and learning rate starting at 0 .01

Data-driven, knowledge-grounded neural conversation models are capable of generating more informative responses. However, these models have not yet demonstrated that they can zero-shot adapt to updated, unseen knowledge graphs. This paper proposes a new task about how to apply dynamic knowledge graphs in neural conversation model and presents a novel TV series conversation corpus (DyKgChat) for the task. Also, we propose a preliminary model that selects an output from two networks at each time step: a sequence-to-sequence model (Seq2Seq) and a multi-hop reasoning model, in order to support dynamic knowledge graphs. To benchmark this new task and evaluate the capability of adaptation, we introduce several evaluation metrics and the experiments show that our proposed approach outperforms previous knowledge-grounded conversation models. The proposed corpus and model can motivate the future research directions 1 . 1 Introduction In the chitchat dialogue generation, neural conversation models (Sutskever et al., 2014; Sordoni et al., 2015; Vinyals and Le, 2015) have emerged for its capability to be fully data-driven and end-to-end trained. While the generated responses are often reasonable but general (without useful information), recent work proposed knowledge-grounded models (Eric et al., 2017; Ghazvinine-jad et al., 2018; Zhou et al., 2018b; Qian et al., 2018) to incorporate external facts in an end-to- end fashion without handcrafted slot filling. Effectively combining text and external knowledge1 The data and code are available in https://github. Nonetheless, prior work rarely analyzed the model capability of zero-shot adaptation to dynamic knowledge graphs, where the states/entities and their relations are temporal and evolve as a single time scale process.

Liquid-based cytology (LBC) is a reliable automated technique for the screening of Papanicolaou (Pap) smear data. It is an effective technique for collecting a majority of the cervical cells and aiding cytopathologists in locating abnormal cells. Most methods published in the research literature rely on accurate cell segmentation as a prior, which remains challenging due to a variety of factors, e.g., stain consistency, presence of clustered cells, etc. We propose a method for automatic classification of cervical slide images through generation of labeled cervical patch data and extracting deep hierarchical features by fine-tuning convolution neural networks, as well as a novel graph-based cell detection approach for cellular level evaluation. The results show that the proposed pipeline can classify images of both single cell and overlapping cells. The VGG-19 model is found to be the best at classifying the cervical cytology patch data with 95 % accuracy under precision-recall curve.

Neural sequence-to-sequence models, particularly the Transformer, are the state of the art in machine translation. Y et these neural networks are very sensitive to architecture and hyper-parameter settings. Optimizing these settings by grid or random search is computationally expensive because it requires many training runs. In this paper, we incorporate architecture search into a single training run through auto-sizing, which uses regularization to delete neurons in a network over the course of training. On very low-resource language pairs, we show that auto-sizing can improve BLEU scores by up to 3.9 points while removing one-third of the parameters from the model.

Representation learning promises to unlock deep learning for the long tail of vision tasks without expansive labelled datasets. Y et, the absence of a unified yardstick to evaluate general visual representations hinders progress. Many sub-fields promise representations, but each has different evaluation protocols that are either too constrained (linear classification), limited in scope (ImageNet, CIFAR, Pascal-VOC), or only loosely related to representation quality (generation). We present the Visual Task Adaptation Benchmark (VT AB): a diverse, realistic, and challenging benchmark to evaluate representations. VT AB embodies one principle: good representations adapt to unseen tasks with few examples . We run a large VT AB study of popular algorithms, answering questions like: How effective are ImageNet representation on nonstandard datasets? Is self-supervision useful if one already has labels? Deep learning has revolutionized computer vision. Distributed representations learned from ...

The dynamics of DNNs during gradient descent is described by the so-called Neural Tangent Kernel (NTK). In this article, we show that the NTK allows one to gain precise insight into the Hessian of the cost of DNNs: we obtain a full characterization of the asymptotics of the spectrum of the Hessian, at initialization and during training.

Quantile QT -Opt for Risk-A ware Vision-Based Robotic Grasping Cristian Bodnar 1, Adrian Li 2, Karol Hausman 3, Peter Pastor 2, Mrinal Kalakrishnan 2 Abstract -- The distributional perspective on reinforcement learning (RL) has given rise to a series of successful Q-learning algorithms, resulting in state-of-the-art performance in arcade game environments. However, it has not yet been analyzed how these findings from a discrete setting translate to complex practical applications characterized by noisy, high dimensional and continuous state-action spaces. In this work, we propose Quantile QT -Opt (Q2-Opt), a distributional variant of the recently introduced distributed Q-learning algorithm [11] for continuous domains, and examine its behaviour in a series of simulated and real vision-based robotic grasping tasks. The absence of an actor in Q2-Opt allows us to directly draw a parallel to the previous discrete experiments in the literature without the additional complexities induced by an actor-critic architecture. We demonstrate that Q2-Opt achieves a superior vision-based object grasping success rate, while also being more sample efficient. The distributional formulation also allows us to experiment with various risk-distortion metrics that give us an indication of how robots can concretely manage risk in practice using a Deep RL control policy. As an additional contribution, we perform experiments on offline datasets and compare them with the latest findings from discrete settings. Surprisingly, we find that there is a discrepancy between our results and the previous batch RL findings from the literature obtained on arcade game environments. I. INTRODUCTION The new distributional perspective on RL has produced a novel class of Deep Q-learning methods that learn a distribution over the state-action returns, instead of using the expectation given by the traditional value function.

Generating graph structures is a challenging problem due to the diverse representations and complex dependencies among nodes. In this paper, we introduce Graph Variational Recurrent Neural Network (GraphVRNN), a probabilistic autoregressive model for graph generation. Through modeling the latent variables of graph data, GraphVRNN can capture the joint distributions of graph structures and the underlying node attributes. We conduct experiments on the proposed GraphVRNN in both graph structure learning and attribute generation tasks. The evaluation results show that the variational component allows our network to model complicated distributions, as well as generate plausible structures and node attributes.