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Neural Information Processing Systems

First provide a summary of the paper, and then address the following criteria: Quality, clarity, originality and significance. The paper proposes an algorithm for estimating the (\delta,\rho) modes of a distribution. The algorithm approximates the distribution using a tree graphical model, constructed using samples from the original distribution, and finds the modes of the tree graphical model. An algorithm for finding the modes of a tree graphical models is proposed, based on constructing an appropriate junction tree to enforce constraints. The algorithm runs in polynomial time in most parameters but in exponential time to the degree of the tree.


Mode Estimation for High Dimensional Discrete Tree Graphical Models

Chao Chen, Han Liu, Dimitris Metaxas, Tianqi Zhao

Neural Information Processing Systems

This paper studies the following problem: given samples from a high dimensional discrete distribution, we want to estimate the leading (δ, ρ)-modes of the underlying distributions. A point is defined to be a (δ, ρ)-mode if it is a local optimum of the density within a δ-neighborhood under metric ρ. As we increase the "scale" parameter δ, the neighborhood size increases and the total number of modes monotonically decreases. The sequence of the (δ, ρ)-modes reveal intrinsic topographical information of the underlying distributions. Though the mode finding problem is generally intractable in high dimensions, this paper unveils that, if the distribution can be approximated well by a tree graphical model, mode characterization is significantly easier. An efficient algorithm with provable theoretical guarantees is proposed and is applied to applications like data analysis and multiple predictions.


Natural Variational Annealing for Multimodal Optimization

Minh, Tâm Le, Arbel, Julyan, Möllenhoff, Thomas, Khan, Mohammad Emtiyaz, Forbes, Florence

arXiv.org Machine Learning

We introduce a new multimodal optimization approach called Natural Variational Annealing (NVA) that combines the strengths of three foundational concepts to simultaneously search for multiple global and local modes of black-box nonconvex objectives. First, it implements a simultaneous search by using variational posteriors, such as, mixtures of Gaussians. Second, it applies annealing to gradually trade off exploration for exploitation. Finally, it learns the variational search distribution using natural-gradient learning where updates resemble well-known and easy-to-implement algorithms. The three concepts come together in NVA giving rise to new algorithms and also allowing us to incorporate "fitness shaping", a core concept from evolutionary algorithms. We assess the quality of search on simulations and compare them to methods using gradient descent and evolution strategies. We also provide an application to a real-world inverse problem in planetary science.


Mode Estimation for High Dimensional Discrete Tree Graphical Models Chao Chen

Neural Information Processing Systems

This paper studies the following problem: given samples from a high dimensional discrete distribution, we want to estimate the leading (δ, ρ)-modes of the underlying distributions. A point is defined to be a (δ, ρ)-mode if it is a local optimum of the density within a δ-neighborhood under metric ρ. As we increase the "scale" parameter δ, the neighborhood size increases and the total number of modes monotonically decreases. The sequence of the (δ, ρ)-modes reveal intrinsic topographical information of the underlying distributions. Though the mode finding problem is generally intractable in high dimensions, this paper unveils that, if the distribution can be approximated well by a tree graphical model, mode characterization is significantly easier. An efficient algorithm with provable theoretical guarantees is proposed and is applied to applications like data analysis and multiple predictions.


Tinder may let you match with users anywhere in the world for free

Engadget

If you can't meet a date in person, then where they live doesn't really matter. That's what Tinder seems to think, anyway. The company is reportedly planning to test a new Global Mode, which will allow profiles to show up around the world, The Verge reports. Users will be able to match with people in other cities, states and even countries. Tinder says it will begin rolling out the "first steps" of Global Mode in late May but that it will take some time before it is available to all members. To start, Global Mode will be a free opt-in feature.


Deep Reinforcement Learning for Green Security Games with Real-Time Information

Wang, Yufei, Shi, Zheyuan Ryan, Yu, Lantao, Wu, Yi, Singh, Rohit, Joppa, Lucas, Fang, Fei

arXiv.org Artificial Intelligence

Green Security Games (GSGs) have been proposed and applied to optimize patrols conducted by law enforcement agencies in green security domains such as combating poaching, illegal logging and overfishing. However, real-time information such as footprints and agents' subsequent actions upon receiving the information, e.g., rangers following the footprints to chase the poacher, have been neglected in previous work. To fill the gap, we first propose a new game model GSG-I which augments GSGs with sequential movement and the vital element of real-time information. Second, we design a novel deep reinforcement learning-based algorithm, DeDOL, to compute a patrolling strategy that adapts to the real-time information against a best-responding attacker. DeDOL is built upon the double oracle framework and the policy-space response oracle, solving a restricted game and iteratively adding best response strategies to it through training deep Q-networks. Exploring the game structure, DeDOL uses domain-specific heuristic strategies as initial strategies and constructs several local modes for efficient and parallelized training. To our knowledge, this is the first attempt to use Deep Q-Learning for security games.


Mode Estimation for High Dimensional Discrete Tree Graphical Models

Chen, Chao, Liu, Han, Metaxas, Dimitris, Zhao, Tianqi

Neural Information Processing Systems

This paper studies the following problem: given samples from a high dimensional discrete distribution, we want to estimate the leading $(\delta,\rho)$-modes of the underlying distributions. A point is defined to be a $(\delta,\rho)$-mode if it is a local optimum of the density within a $\delta$-neighborhood under metric $\rho$. As we increase the ``scale'' parameter $\delta$, the neighborhood size increases and the total number of modes monotonically decreases. The sequence of the $(\delta,\rho)$-modes reveal intrinsic topographical information of the underlying distributions. Though the mode finding problem is generally intractable in high dimensions, this paper unveils that, if the distribution can be approximated well by a tree graphical model, mode characterization is significantly easier. An efficient algorithm with provable theoretical guarantees is proposed and is applied to applications like data analysis and multiple predictions.