Learning Graphical Models
Synergizing Domain Expertise with Self-Awareness in Software Systems: A Patternized Architecture Guideline
Chen, Tao, Bahsoon, Rami, Yao, Xin
Architectural patterns provide a reusable architectural solution for commonly recurring problems that can assist in designing software systems. In this regard, self-awareness architectural patterns are specialized patterns that leverage good engineering practices and experiences to help in designing self-awareness and self-adaptation of a software system. However, domain knowledge and engineers' expertise that is built over time are not explicitly linked to these patterns and the self-aware process. This linkage is important, as it can enrich the design patterns of these systems, which consequently leads to more effective and efficient self-aware and self-adaptive behaviours. This paper is an introductory work that highlights the importance of synergizing domain expertise into the self-awareness in software systems, relying on well-defined underlying approaches. In particular, we present a holistic framework that classifies widely known representations used to obtain and maintain the domain expertise, documenting their nature and specifics rules that permits different levels of synergies with self-awareness. Drawing on such, we describe mechanisms that can enrich existing patterns with engineers' expertise and knowledge of the domain. This, together with the framework, allow us to codify an intuitive step-by-step methodology that guides engineer in making design decisions when synergizing domain expertise into self-awareness and reveal their importances, in an attempt to keep 'engineers-in-the-loop'. Through three case studies, we demonstrate how the enriched patterns, the proposed framework and methodology can be applied in different domains, within which we quantitatively compare the actual benefits of incorporating engineers' expertise into self-awareness, at alternative levels of synergies.
Exact Information Bottleneck with Invertible Neural Networks: Getting the Best of Discriminative and Generative Modeling
Ardizzone, Lynton, Mackowiak, Radek, Köthe, Ullrich, Rother, Carsten
The Information Bottleneck (IB) principle offers a unified approach to many learning and prediction problems. Although optimal in an information-theoretic sense, practical applications of IB are hampered by a lack of accurate high-dimensional estimators of mutual information, its main constituent. We propose to combine IB with invertible neural networks (INNs), which for the first time allows exact calculation of the required mutual information. Applied to classification, our proposed method results in a generative classifier we call IB-INN. It accurately models the class conditional likelihoods, generalizes well to unseen data and reliably recognizes out-of-distribution examples. In contrast to existing generative classifiers, these advantages incur only minor reductions in classification accuracy in comparison to corresponding discriminative methods such as feed-forward networks. Furthermore, we provide insight into why IB-INNs are superior to other generative architectures and training procedures and show experimentally that our method outperforms alternative models of comparable complexity.
AutoMATES: Automated Model Assembly from Text, Equations, and Software
Pyarelal, Adarsh, Valenzuela-Escarcega, Marco A., Sharp, Rebecca, Hein, Paul D., Stephens, Jon, Bhandari, Pratik, Lim, HeuiChan, Debray, Saumya, Morrison, Clayton T.
There exist today state-of-the-art computational models that can provide highly accurate predictions about complex phenomena such as crop growth and weather patterns. However, certain phenomena, such as food insecurity, involve a host of factors that cannot be modeled by any single one of these models, but which instead require the integration of multiple models. To truly integrate these computational models, it is necessary to'lift' them to a common representation that is (i) agnostic to the software implementation, (ii) semantically rich enough to represent the implicit domain knowledge in the models, and (iii) connected to the domain literature. The AutoMATES project aims to build technology to construct and curate semantically-rich representations of scientific models by integrating three different sources of information: - natural language descriptions of models in publications and other technical documentation, - the equations contained in these documents, and - the software the implements these models. An example of a model being represented in these three forms (text, equations, and software) is shown in Figure 1. This model is a differential equation describing the biophysical variable, leaf area index (LAI). The network on the right half of the figure is an aspirational representation of the model as a Bayesian network. Although this example is handcrafted, our end goal is to be able to automatically assemble models with this level of semantic richness.
The Incentives that Shape Behaviour
Carey, Ryan, Langlois, Eric, Everitt, Tom, Legg, Shane
Which variables does an agent have an incentive to control with its decision, and which variables does it have an incentive to respond to? We formalize these incentives, and demonstrate unique graphical criteria for detecting them in any single-decision causal influence diagram. To this end, we introduce structural causal influence models, a hybrid of the influence diagram and structural causal model frameworks. Finally, we illustrate how these incentives predict agent incentives in both fairness and AI safety applications.
Adventures With Artificial Intelligence and Machine Learning
Since October of last year I have had the opportunity to work with an startup working on automated machine learning and I thought that I would share some thoughts on the experience and the details of what one might want to consider around the start of a journey with a "data scientist in a box". I'll start by saying that machine learning and'artificial intelligence has almost forced itself into my work several times in the past eighteen months, all in slightly different ways. The first brush was back in June 2018 when one of the developers I was working with wanted to demonstrate to me a scoring model for loan applications based on the analysis of some other transactional data that indicated loans that had been previously granted. The model had no explanation and no details other than the fact that it allowed you to stitch together a transactional dataset which it assessed using a naïve Bayes algorithm. We had a run at showing this to a wider audience but the palate for examination seemed low and I suspect that in the end the real reason was we didn't have real data and only had a conceptual problem to be solved.
Mode-Assisted Unsupervised Learning of Restricted Boltzmann Machines
Manukian, Haik, Pei, Yan Ru, Bearden, Sean R. B., Di Ventra, Massimiliano
Restricted Boltzmann machines (RBMs) are a powerful class of generative models, but their training requires computing a gradient that, unlike supervised backpropagation on typical loss functions, is notoriously difficult even to approximate. Here, we show that properly combining standard gradient updates with an off-gradient direction, constructed from samples of the RBM ground state (mode), improves their training dramatically over traditional gradient methods. This approach, which we call mode training, promotes faster training and stability, in addition to lower converged relative entropy (KL divergence). Along with the proofs of stability and convergence of this method, we also demonstrate its efficacy on synthetic datasets where we can compute KL divergences exactly, as well as on a larger machine learning standard, MNIST. The mode training we suggest is quite versatile, as it can be applied in conjunction with any given gradient method, and is easily extended to more general energy-based neural network structures such as deep, convolutional and unrestricted Boltzmann machines.
A meta-algorithm for classification using random recursive tree ensembles: A high energy physics application
The aim of this work is to propose a meta-algorithm for automatic classification in the presence of discrete binary classes. Classifier learning in the presence of overlapping class distributions is a challenging problem in machine learning. Overlapping classes are described by the presence of ambiguous areas in the feature space with a high density of points belonging to both classes. This often occurs in real-world datasets, one such example is numeric data denoting properties of particle decays derived from high-energy accelerators like the Large Hadron Collider (LHC). A significant body of research targeting the class overlap problem use ensemble classifiers to boost the performance of algorithms by using them iteratively in multiple stages or using multiple copies of the same model on different subsets of the input training data. The former is called boosting and the latter is called bagging. The algorithm proposed in this thesis targets a challenging classification problem in high energy physics - that of improving the statistical significance of the Higgs discovery. The underlying dataset used to train the algorithm is experimental data built from the official ATLAS full-detector simulation with Higgs events (signal) mixed with different background events (background) that closely mimic the statistical properties of the signal generating class overlap. The algorithm proposed is a variant of the classical boosted decision tree which is known to be one of the most successful analysis techniques in experimental physics. The algorithm utilizes a unified framework that combines two meta-learning techniques - bagging and boosting. The results show that this combination only works in the presence of a randomization trick in the base learners.
Learning Options from Demonstration using Skill Segmentation
Cockcroft, Matthew, Mawjee, Shahil, James, Steven, Ranchod, Pravesh
We present a method for learning options from segmented demonstration trajectories. The trajectories are first segmented into skills using nonparametric Bayesian clustering and a reward function for each segment is then learned using inverse reinforcement learning. From this, a set of inferred trajectories for the demonstration are generated. Option initiation sets and termination conditions are learned from these trajectories using the one-class support vector machine clustering algorithm. We demonstrate our method in the four rooms domain, where an agent is able to autonomously discover usable options from human demonstration. Our results show that these inferred options can then be used to improve learning and planning.
An Approach for Time-aware Domain-based Social Influence Prediction
Abu-Salih, Bilal, Chan, Kit Yan, Al-Kadi, Omar, Al-Tawil, Marwan, Wongthongtham, Pornpit, Issa, Tomayess, Saadeh, Heba, Al-Hassan, Malak, Bremie, Bushra, Albahlal, Abdulaziz
Online Social Networks(OSNs) have established virtual platforms enabling people to express their opinions, interests and thoughts in a variety of contexts and domains, allowing legitimate users as well as spammers and other untrustworthy users to publish and spread their content. Hence, the concept of social trust has attracted the attention of information processors/data scientists and information consumers/business firms. One of the main reasons for acquiring the value of Social Big Data (SBD) is to provide frameworks and methodologies using which the credibility of OSNs users can be evaluated. These approaches should be scalable to accommodate large-scale social data. Hence, there is a need for well comprehending of social trust to improve and expand the analysis process and inferring the credibility of SBD. Given the exposed environment's settings and fewer limitations related to OSNs, the medium allows legitimate and genuine users as well as spammers and other low trustworthy users to publish and spread their content. Hence, this paper presents an approach incorporates semantic analysis and machine learning modules to measure and predict users' trustworthiness in numerous domains in different time periods. The evaluation of the conducted experiment validates the applicability of the incorporated machine learning techniques to predict highly trustworthy domain-based users.
Effects of sparse rewards of different magnitudes in the speed of learning of model-based actor critic methods
Vargas, Juan, Andjelic, Lazar, Farimani, Amir Barati
Actor critic methods with sparse rewards in model-based deep reinforcement learning typically require a deterministic binary reward function that reflects only two possible outcomes: if, for each step, the goal has been achieved or not. Our hypothesis is that we can influence an agent to learn faster by applying an external environmental pressure during training, which adversely impacts its ability to get higher rewards. As such, we deviate from the classical paradigm of sparse rewards and add a uniformly sampled reward value to the baseline reward to show that (1) sample efficiency of the training process can be correlated to the adversity experienced during training, (2) it is possible to achieve higher performance in less time and with less resources, (3) we can reduce the performance variability experienced seed over seed, (4) there is a maximum point after which more pressure will not generate better results, and (5) that random positive incentives have an adverse effect when using a negative reward strategy, making an agent under those conditions learn poorly and more slowly. These results have been shown to be valid for Deep Deterministic Policy Gradients using Hindsight Experience Replay in a well known Mujoco environment, but we argue that they could be generalized to other methods and environments as well.