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 Learning Graphical Models


Scientists believe they've nailed the combination that could help robots feel love

#artificialintelligence

The proposal to open Café fellatio, an establishment in Geneva, Switzerland where men would be able to get oral sex while drinking their coffee, was met with no uncertain outrage. And city authorities have decided it's also against Swiss law. It's not clear what the robots would look like or what they'd be able to do. The Geneva authorities have also yet to make up their mind whether that's an acceptable solution. On the one hand, you could argue that these sorts of robots, presumably looking as human-like as possible, are nothing more than technologically advanced sex toys--the dildos and fleshlights of the digital age.


From classic AI techniques to Deep Reinforcement Learning

@machinelearnbot

Building machines that can learn from examples, experience, or even from another machines at human level are the main goal of solving AI. That goal in other words is to create a machine that pass the Turing test: when a human is interacting with it, for the human it will not possible to conclude if it he is interacting with a human or a machine [Turing, A.M 1950]. The fundamental algorithms of deep learning were developed in the middle of 20th century. Since them the field was developed as a theory branch of stochastic operations research and computer science, but without any breakthrough application. But, in the last 20 years the synergy between big data sets, specially labeled data, and augmentation of computer power using graphics processor units, those algorithms have been developed in more complex techniques, technologies and reasoning logics enable to achieve several goals as reducing word error rates in speech recognition; cutting the error rate in an image recognition competition [Krizhevsky et al 2012] and beating a human champion at Go [Silver et al 2016].


Markov Chains explained visually

#artificialintelligence

Markov chains, named after Andrey Markov, are mathematical systems that hop from one "state" (a situation or set of values) to another. For example, if you made a Markov chain model of a baby's behavior, you might include "playing," "eating", "sleeping," and "crying" as states, which together with other behaviors could form a'state space': a list of all possible states. In addition, on top of the state space, a Markov chain tells you the probabilitiy of hopping, or "transitioning," from one state to any other state---e.g., the chance that a baby currently playing will fall asleep in the next five minutes without crying first. A simple, two-state Markov chain is shown below. With two states (A and B) in our state space, there are 4 possible transitions (not 2, because a state can transition back into itself).


Continuous Semantic Topic Embedding Model Using Variational Autoencoder

arXiv.org Machine Learning

This paper proposes the continuous semantic topic embedding model (CSTEM) which finds latent topic variables in documents using continuous semantic distance function between the topics and the words by means of the vari-ational autoencoder(V AE). The semantic distance could be represented by any symmetric bell-shaped geometric distance function on the Euclidean space, for which the Mahalanobis distance is used in this paper. In order for the semantic distance to perform more properly, we newly introduce an additional model parameter for each word to take out the global factor from this distance indicating how likely it occurs regardless of its topic. It certainly improves the problem that the Gaussian distribution which is used in previous topic model with continuous word embedding could not explain the semantic relation correctly and helps to obtain the higher topic coherence. Through the experiments with the dataset of 20 Newsgroup, NIPS papers and CNN/Dailymail corpus, the performance of the recent state-of-the-art models is accomplished by our model as well as generating topic embedding vectors which makes possible to observe where the topic vectors are embedded with the word vectors in the real Euclidean space and how the topics are related each other semantically.


Inference via low-dimensional couplings

arXiv.org Machine Learning

We investigate the low-dimensional structure of deterministic transformations between random variables, i.e., transport maps between probability measures. In the context of statistics and machine learning, these transformations can be used to couple a tractable "reference" measure (e.g., a standard Gaussian) with a target measure of interest. Direct simulation from the desired measure can then be achieved by pushing forward reference samples through the map. Yet characterizing such a map---e.g., representing and evaluating it---grows challenging in high dimensions. The central contribution of this paper is to establish a link between the Markov properties of the target measure and the existence of low-dimensional couplings, induced by transport maps that are sparse and/or decomposable. Our analysis not only facilitates the construction of transformations in high-dimensional settings, but also suggests new inference methodologies for continuous non-Gaussian graphical models. For instance, in the context of nonlinear state-space models, we describe new variational algorithms for filtering, smoothing, and sequential parameter inference. These algorithms can be understood as the natural generalization---to the non-Gaussian case---of the square-root Rauch-Tung-Striebel Gaussian smoother.


Essentials of Machine Learning Algorithms (with Python and R Codes)

@machinelearnbot

KNN can easily be mapped to our real lives. If you want to learn about a person, of whom you have no information, you might like to find out about his close friends and the circles he moves in and gain access to his/her information!


BBQ-Networks: Efficient Exploration in Deep Reinforcement Learning for Task-Oriented Dialogue Systems

arXiv.org Machine Learning

We present a new algorithm that significantly improves the efficiency of exploration for deep Q-learning agents in dialogue systems. Our agents explore via Thompson sampling, drawing Monte Carlo samples from a Bayes-by-Backprop neural network. Our algorithm learns much faster than common exploration strategies such as $\epsilon$-greedy, Boltzmann, bootstrapping, and intrinsic-reward-based ones. Additionally, we show that spiking the replay buffer with experiences from just a few successful episodes can make Q-learning feasible when it might otherwise fail.


Diversity-Promoting Bayesian Learning of Latent Variable Models

arXiv.org Machine Learning

To address three important issues involved in latent variable models (LVMs), including capturing infrequent patterns, achieving small-sized but expressive models and alleviating overfitting, several studies have been devoted to "diversifying" LVMs, which aim at encouraging the components in LVMs to be diverse. Most existing studies fall into a frequentist-style regularization framework, where the components are learned via point estimation. In this paper, we investigate how to "diversify" LVMs in the paradigm of Bayesian learning. We propose two approaches that have complementary advantages. One is to define a diversity-promoting mutual angular prior which assigns larger density to components with larger mutual angles and use this prior to affect the posterior via Bayes' rule. We develop two efficient approximate posterior inference algorithms based on variational inference and MCMC sampling. The other approach is to impose diversity-promoting regularization directly over the post-data distribution of components. We also extend our approach to "diversify" Bayesian nonparametric models where the number of components is infinite. A sampling algorithm based on slice sampling and Hamiltonian Monte Carlo is developed. We apply these methods to "diversify" Bayesian mixture of experts model and infinite latent feature model. Experiments on various datasets demonstrate the effectiveness and efficiency of our methods.


Bayesian Nonparametric Models

@machinelearnbot

Bayesian Nonparametrics is a class of models with a potentially infinite number of parameters. High flexibility and expressive power of this approach enables better data modelling compared to parametric methods.


Dynamic classifier chains for multi-label learning

arXiv.org Machine Learning

In this paper, we deal with the task of building a dynamic ensemble of chain classifiers for multi-label classification. To do so, we proposed two concepts of classifier chains algorithms that are able to change label order of the chain without rebuilding the entire model. Such modes allows anticipating the instance-specific chain order without a significant increase in computational burden. The proposed chain models are built using the Naive Bayes classifier and nearest neighbour approach as a base single-label classifiers. To take the benefits of the proposed algorithms, we developed a simple heuristic that allows the system to find relatively good label order. The heuristic sort labels according to the label-specific classification quality gained during the validation phase. The heuristic tries to minimise the phenomenon of error propagation in the chain. The experimental results showed that the proposed model based on Naive Bayes classifier the above-mentioned heuristic is an efficient tool for building dynamic chain classifiers.