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 Uncertainty


Modelling and Optimisation of Resource Usage in an IoT Enabled Smart Campus

arXiv.org Artificial Intelligence

University campuses are essentially a microcosm of a city. They comprise diverse facilities such as residences, sport centres, lecture theatres, parking spaces, and public transport stops. Universities are under constant pressure to improve efficiencies while offering a better experience to various stakeholders including students, staff, and visitors. Nonetheless, anecdotal evidence indicates that campus assets are not being utilised efficiently, often due to the lack of data collection and analysis, thereby limiting the ability to make informed decisions on the allocation and management of resources. Advances in the Internet of Things (IoT) technologies that can sense and communicate data from the physical world, coupled with data analytics and Artificial intelligence (AI) that can predict usage patterns, have opened up new opportunities for organisations to lower cost and improve user experience. This thesis explores this opportunity via theory and experimentation using UNSW Sydney as a living laboratory.


Kernel Methods for Multistage Causal Inference: Mediation Analysis and Dynamic Treatment Effects

arXiv.org Machine Learning

We propose kernel ridge regression estimators for mediation analysis and dynamic treatment effects over short horizons. We allow treatments, covariates, and mediators to be discrete or continuous, and low, high, or infinite dimensional. We propose estimators of means, increments, and distributions of counterfactual outcomes with closed form solutions in terms of kernel matrix operations. For the continuous treatment case, we prove uniform consistency with finite sample rates. For the discrete treatment case, we prove root-n consistency, Gaussian approximation, and semiparametric efficiency. We conduct simulations then estimate mediated and dynamic treatment effects of the US Job Corps program for disadvantaged youth.


Deep Neyman-Scott Processes

arXiv.org Machine Learning

A Neyman-Scott process is a special case of a Cox process. The latent and observable stochastic processes are both Poisson processes. We consider a deep Neyman-Scott process in this paper, for which the building components of a network are all Poisson processes. We develop an efficient posterior sampling via Markov chain Monte Carlo and use it for likelihood-based inference. Our method opens up room for the inference in sophisticated hierarchical point processes. We show in the experiments that more hidden Poisson processes brings better performance for likelihood fitting and events types prediction. We also compare our method with state-of-the-art models for temporal real-world datasets and demonstrate competitive abilities for both data fitting and prediction, using far fewer parameters.


Contextual Bayesian optimization with binary outputs

arXiv.org Machine Learning

Bayesian optimization (BO) is an efficient method to optimize expensive black-box functions. It has been generalized to scenarios where objective function evaluations return stochastic binary feedback, such as success/failure in a given test, or preference between different parameter settings. In many real-world situations, the objective function can be evaluated in controlled 'contexts' or 'environments' that directly influence the observations. For example, one could directly alter the 'difficulty' of the test that is used to evaluate a system's performance. With binary feedback, the context determines the information obtained from each observation. For example, if the test is too easy/hard, the system will always succeed/fail, yielding uninformative binary outputs. Here we combine ideas from Bayesian active learning and optimization to efficiently choose the best context and optimization parameter on each iteration. We demonstrate the performance of our algorithm and illustrate how it can be used to tackle a concrete application in visual psychophysics: efficiently improving patients' vision via corrective lenses, using psychophysics measurements.


Perturb-and-max-product: Sampling and learning in discrete energy-based models

arXiv.org Machine Learning

Perturb-and-MAP offers an elegant approach to approximately sample from a energy-based model (EBM) by computing the maximum-a-posteriori (MAP) configuration of a perturbed version of the model. Sampling in turn enables learning. However, this line of research has been hindered by the general intractability of the MAP computation. Very few works venture outside tractable models, and when they do, they use linear programming approaches, which as we will show, have several limitations. In this work we present perturb-and-max-product (PMP), a parallel and scalable mechanism for sampling and learning in discrete EBMs. Models can be arbitrary as long as they are built using tractable factors. We show that (a) for Ising models, PMP is orders of magnitude faster than Gibbs and Gibbs-with-Gradients (GWG) at learning and generating samples of similar or better quality; (b) PMP is able to learn and sample from RBMs; (c) in a large, entangled graphical model in which Gibbs and GWG fail to mix, PMP succeeds.


Shared Model of Sense-making for Human-Machine Collaboration

arXiv.org Artificial Intelligence

We present a model of sense-making that greatly facilitates the collaboration between an intelligent analyst and a knowledge-based agent. It is a general model grounded in the science of evidence and the scientific method of hypothesis generation and testing, where sense-making hypotheses that explain an observation are generated, relevant evidence is then discovered, and the hypotheses are tested based on the discovered evidence. We illustrate how the model enables an analyst to directly instruct the agent to understand situations involving the possible production of weapons (e.g., chemical warfare agents) and how the agent becomes increasingly more competent in understanding other situations from that domain (e.g., possible production of centrifuge-enriched uranium or of stealth fighter aircraft).


An Empirical Study of Neural Kernel Bandits

arXiv.org Artificial Intelligence

Neural bandits have enabled practitioners to operate efficiently on problems with non-linear reward functions. While in general contextual bandits commonly utilize Gaussian process (GP) predictive distributions for decision making, the most successful neural variants use only the last layer parameters in the derivation. Research on neural kernels (NK) has recently established a correspondence between deep networks and GPs that take into account all the parameters of a NN and can be trained more efficiently than most Bayesian NNs. We propose to directly apply NK-induced distributions to guide an upper confidence bound or Thompson sampling-based policy. We show that NK bandits achieve state-of-the-art performance on highly non-linear structured data. Furthermore, we analyze practical considerations such as training frequency and model partitioning. We believe our work will help better understand the impact of utilizing NKs in applied settings.


Probabilistic Deep Learning for Wind Turbines

#artificialintelligence

Model speed can be a deal breaker on large datasets. Leveraging an empirical study, we will look at two dimension reduction techniques and how they can be applied to a Gaussian Processes. Regarding implementation of the method, anyone familiar with the basics of conditional probability can develop a Gaussian Process model. However, to fully leverage the capabilities of the framework, a fair amount of in-depth knowledge is required. Gaussian processes also are not very computationally efficient, but their flexibility is makes them a common choice for niche regression problems.


Application of Fuzzy Set Theory to Setup Planning

#artificialintelligence

Computer-aided process planning and computer-aided fixture planning have been widely researched in the last two decades. Most of these computer-aided systems are, however, either dealing only with process planning or fixture design. A set-up planning system for the machining of prismatic parts on a 3-axis vertical machining centre is proposed. This system formulates set-up plans based on the initial, intermediate and final states of a part. The system uses the fuzzy set representation, along with production rules and object representation.


Amortized Variational Inference for Simple Hierarchical Models

arXiv.org Machine Learning

It is difficult to use subsampling with variational inference in hierarchical models since the number of local latent variables scales with the dataset. Thus, inference in hierarchical models remains a challenge at large scale. It is helpful to use a variational family with structure matching the posterior, but optimization is still slow due to the huge number of local distributions. Instead, this paper suggests an amortized approach where shared parameters simultaneously represent all local distributions. This approach is similarly accurate as using a given joint distribution (e.g., a full-rank Gaussian) but is feasible on datasets that are several orders of magnitude larger. It is also dramatically faster than using a structured variational distribution.