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 Supervised Learning


Addressing the Fundamental Tension of PCGML with Discriminative Learning

arXiv.org Machine Learning

Procedural content generation via machine learning (PCGML) is typically framed as the task of fitting a generative model to full-scale examples of a desired content distribution. This approach presents a fundamental tension: the more design effort expended to produce detailed training examples for shaping a generator, the lower the return on investment from applying PCGML in the first place. In response, we propose the use of discriminative models (which capture the validity of a design rather the distribution of the content) trained on positive and negative examples. Through a modest modification of WaveFunctionCollapse, a commercially-adopted PCG approach that we characterize as using elementary machine learning, we demonstrate a new mode of control for learning-based generators. We demonstrate how an artist might craft a focused set of additional positive and negative examples by critique of the generator's previous outputs. This interaction mode bridges PCGML with mixed-initiative design assistance tools by working with a machine to define a space of valid designs rather than just one new design.


Learning Multilingual Word Embeddings in Latent Metric Space: A Geometric Approach

arXiv.org Artificial Intelligence

We propose a novel geometric approach for learning bilingual mappings given monolingual embeddings and a bilingual dictionary. Our approach decouples learning the transformation from the source language to the target language into (a) learning rotations for language-specific embeddings to align them to a common space, and (b) learning a similarity metric in the common space to model similarities between the embeddings. We model the bilingual mapping problem as an optimization problem on smooth Riemannian manifolds. We show that our approach outperforms previous approaches on the bilingual lexicon induction and cross-lingual word similarity tasks. We also generalize our framework to represent multiple languages in a common latent space. In particular, the latent space representations for several languages are learned jointly, given bilingual dictionaries for multiple language pairs. We illustrate the effectiveness of joint learning for multiple languages in zero-shot word translation setting.


Local Linear Forests โ€“ Arxiv Vanity

#artificialintelligence

In order to address this weakness, we take the perspective of random forests as an adaptive kernel method. This interpretation follows work by Athey et al. (2018), Hothorn et al. (2004), and Meinshausen (2006), and complements the traditional view of forests as an ensemble method (i.e., an average of predictions made by individual trees). These types of adjustments are particularly important near boundaries, where neighborhoods are asymmetric by necessity, but with many covariates, the adjustments are also important away from boundaries given that local neighborhoods are often unbalanced due to sampling variation. The goal of this paper is improve the accuracy of forests on smooth signals using regression adjustments, potentially in many dimensions. By using the local regression adjustment, it is possible to adjust for asymmetries and imbalances in the set of nearby points used for prediction, ensuring that the weighted average of the feature vector of neighboring points is approximately equal to the target feature vector, and that predictions are centered.


Story Disambiguation: Tracking Evolving News Stories across News and Social Streams

arXiv.org Machine Learning

Following a particular news story online is an important but difficult task, as the relevant information is often scattered across different domains/sources (e.g., news articles, blogs, comments, tweets), presented in various formats and language styles, and may overlap with thousands of other stories. In this work we join the areas of topic tracking and entity disambiguation, and propose a framework named Story Disambiguation - a cross-domain story tracking approach that builds on real-time entity disambiguation and a learning-to-rank framework to represent and update the rich semantic structure of news stories. Given a target news story, specified by a seed set of documents, the goal is to effectively select new story-relevant documents from an incoming document stream. We represent stories as entity graphs and we model the story tracking problem as a learning-to-rank task. This enables us to track content with high accuracy, from multiple domains, in real-time. We study a range of text, entity and graph based features to understand which type of features are most effective for representing stories. We further propose new semi-supervised learning techniques to automatically update the story representation over time. Our empirical study shows that we outperform the accuracy of state-of-the-art methods for tracking mixed-domain document streams, while requiring fewer labeled data to seed the tracked stories. This is particularly the case for local news stories that are easily over shadowed by other trending stories, and for complex news stories with ambiguous content in noisy stream environments.


Rainfall Records Set Across North Carolina During Soggy July

U.S. News

The weather service reported Cape Hatteras got 20.31 inches (50 centimeters) of rain last month, well above the normal of 4.99 inches (12.66 centimeters), based on a 30-year average. It's the wettest July on record and the second wettest month ever, trailing only the 21.40 inches (54 centimeters) that fell on Cape Hatteras in September 1999 due to Hurricane Floyd.


Tulane University: Fundraising Record Set With $150M Raised

U.S. News

Among the major donations: $25 million from the family of Dr. John Winton Deming to name the John W. Deming Department of Medicine; and a $10 million gift from Tulane alumni Steven and Jann Paul to build the Steven and Jann Paul Hall for Science and Engineering. There also was an anonymous lead gift and other donations to begin construction on a $55 million building to be called The Commons, which will include a new dining hall and meeting spaces.


Making Classifier Chains Resilient to Class Imbalance

arXiv.org Machine Learning

Class imbalance is an intrinsic characteristic of multi-label data. Most of the labels in multi-label data sets are associated with a small number of training examples, much smaller compared to the size of the data set. Class imbalance poses a key challenge that plagues most multi-label learning methods. Ensemble of Classifier Chains (ECC), one of the most prominent multi-label learning methods, is no exception to this rule, as each of the binary models it builds is trained from all positive and negative examples of a label. To make ECC resilient to class imbalance, we first couple it with random undersampling. We then present two extensions of this basic approach, where we build a varying number of binary models per label and construct chains of different sizes, in order to improve the exploitation of majority examples with approximately the same computational budget. Experimental results on 16 multi-label datasets demonstrate the effectiveness of the proposed approaches in a variety of evaluation metrics.


Leveraging Knowledge Graph Embedding Techniques for Industry 4.0 Use Cases

arXiv.org Artificial Intelligence

Industry is evolving towards Industry 4.0, which holds the promise of increased flexibility in manufacturing, better quality and improved productivity. A core actor of this growth is using sensors, which must capture data that can used in unforeseen ways to achieve a performance not achievable without them. However, the complexity of this improved setting is much greater than what is currently used in practice. Hence, it is imperative that the management cannot only be performed by human labor force, but part of that will be done by automated algorithms instead. A natural way to represent the data generated by this large amount of sensors, which are not acting measuring independent variables, and the interaction of the different devices is by using a graph data model. Then, machine learning could be used to aid the Industry 4.0 system to, for example, perform predictive maintenance. However, machine learning directly on graphs, needs feature engineering and has scalability issues. In this paper we discuss methods to convert (embed) the graph in a vector space, such that it becomes feasible to use traditional machine learning methods for Industry 4.0 settings.


One-Class Kernel Spectral Regression for Outlier Detection

arXiv.org Machine Learning

The paper introduces a new efficient nonlinear one-class classifier formulated as the Rayleigh quotient criterion. The method, operating in a reproducing kernel Hilbert subspace, minimises the scatter of target distribution along an optimal projection direction while at the same time keeping projections of positive observations as distant as possible from the mean of the negative class. We provide a graph embedding view of the problem which can then be solved efficiently using the spectral regression approach. In this sense, unlike previous similar methods which often require costly eigen-computations of dense matrices, the proposed approach casts the problem under consideration into a regression framework which avoids eigen-decomposition computations. In particular, it is shown that the dominant complexity of the proposed method is the complexity of computing the kernel matrix. Additional appealing characteristics of the proposed one-class classifier are: 1-the ability to be trained in an incremental fashion (allowing for application in streaming data scenarios while also reducing computational complexity in a non-streaming operation mode); 2-being unsupervised while also providing the functionality for refining the solution using negative training examples, in case available; And last but not least 3-the deployment of the kernel trick allowing for nonlinearly mapping the data into a high-dimensional feature space. Extensive experiments conducted on several datasets verify the merits of the proposed approach in comparison with some other alternatives.


Towards Non-Parametric Learning to Rank

arXiv.org Machine Learning

This paper studies a stylized, yet natural, learning-to-rank problem and points out the critical incorrectness of a widely used nearest neighbor algorithm. We consider a model with $n$ agents (users) $\{x_i\}_{i \in [n]}$ and $m$ alternatives (items) $\{y_j\}_{j \in [m]}$, each of which is associated with a latent feature vector. Agents rank items nondeterministically according to the Plackett-Luce model, where the higher the utility of an item to the agent, the more likely this item will be ranked high by the agent. Our goal is to find neighbors of an arbitrary agent or alternative in the latent space. We first show that the Kendall-tau distance based kNN produces incorrect results in our model. Next, we fix the problem by introducing a new algorithm with features constructed from "global information" of the data matrix. Our approach is in sharp contrast to most existing feature engineering methods. Finally, we design another new algorithm identifying similar alternatives. The construction of alternative features can be done using "local information," highlighting the algorithmic difference between finding similar agents and similar alternatives.