Uncertainty
Eindhoven, Netherlands - Assistant Professor Job in AI, Machine learning
We seek to appoint an assistant or associate professor in the general area of Uncertainty in AI, who is passionate about research as well as teaching. We particularly welcome excellent candidates that can contribute to foundational aspects of AI and machine learning.The successful candidate will help with developing and/or delivering courses in DAI cluster, such as Foundations of AI, Explainable AI, Text Mining, Reinforcement Learning, Uncertainty Representation and Reasoning, and Generative Models, and will supervise students at all levels. The working language in the department and across the university is English. An important aspect of TU/e's vision on education is that research and education go hand in hand, both at Bachelor and Master level.Next to your research, education is an important part of your job.The TU/e helps its scientific staff to further develop their teaching skills by offering a training program that leads to an official teaching certification from Dutch Universities (Basic Teaching Qualification).Furthermore, you should have: Are you inspired to work for the exciting Department of Mathematics and Computer Science at TU Eindhoven? We're looking for you as our new faculty member to expand our academic staff in the Data and AI cluster.
On robust risk-based active-learning algorithms for enhanced decision support
Hughes, Aidan J., Bull, Lawrence A., Gardner, Paul, Dervilis, Nikolaos, Worden, Keith
Classification models are a fundamental component of physical-asset management technologies such as structural health monitoring (SHM) systems and digital twins. Previous work introduced \textit{risk-based active learning}, an online approach for the development of statistical classifiers that takes into account the decision-support context in which they are applied. Decision-making is considered by preferentially querying data labels according to \textit{expected value of perfect information} (EVPI). Although several benefits are gained by adopting a risk-based active learning approach, including improved decision-making performance, the algorithms suffer from issues relating to sampling bias as a result of the guided querying process. This sampling bias ultimately manifests as a decline in decision-making performance during the later stages of active learning, which in turn corresponds to lost resource/utility. The current paper proposes two novel approaches to counteract the effects of sampling bias: \textit{semi-supervised learning}, and \textit{discriminative classification models}. These approaches are first visualised using a synthetic dataset, then subsequently applied to an experimental case study, specifically, the Z24 Bridge dataset. The semi-supervised learning approach is shown to have variable performance; with robustness to sampling bias dependent on the suitability of the generative distributions selected for the model with respect to each dataset. In contrast, the discriminative classifiers are shown to have excellent robustness to the effects of sampling bias. Moreover, it was found that the number of inspections made during a monitoring campaign, and therefore resource expenditure, could be reduced with the careful selection of the statistical classifiers used within a decision-supporting monitoring system.
Optimality in Noisy Importance Sampling
Llorente, Fernando, Martino, Luca, Read, Jesse, Delgado-Gómez, David
A wide range of modern applications, especially in Bayesian inference framework [1], require the study of probability density functions (pdfs) which can be evaluated stochastically, i.e., only noisy evaluations can be obtained [2, 3, 4, 5]. For instance, this is the case of the pseudo-marginal approaches and doubly intractable posteriors [6, 7], approximate Bayesian computation (ABC) and likelihood-free schemes [8, 9], where the target density cannot be computed in closed-form. The noisy scenario also appears naturally when mini-batches of data are employed instead of considering the complete likelihood of huge amounts of data [10, 11]. More recently, the analysis of noisy functions of densities is required in reinforcement learning (RL), especially in direct policy search which is an important branch of RL, with applications in robotics [12, 13]. The topic of inference in noisy settings (or where a function is known with a certain degree of uncertainty) is also of interest in the inverse problem literature, such as in the calibration of expensive computer codes [14, 15]. This is also the case when the construction of an emulator is considered, as a surrogate model [4, 16, 17].
Unified Field Theory for Deep and Recurrent Neural Networks
Segadlo, Kai, Epping, Bastian, van Meegen, Alexander, Dahmen, David, Krämer, Michael, Helias, Moritz
Understanding capabilities and limitations of different network architectures is of fundamental importance to machine learning. Bayesian inference on Gaussian processes has proven to be a viable approach for studying recurrent and deep networks in the limit of infinite layer width, $n\to\infty$. Here we present a unified and systematic derivation of the mean-field theory for both architectures that starts from first principles by employing established methods from statistical physics of disordered systems. The theory elucidates that while the mean-field equations are different with regard to their temporal structure, they yet yield identical Gaussian kernels when readouts are taken at a single time point or layer, respectively. Bayesian inference applied to classification then predicts identical performance and capabilities for the two architectures. Numerically, we find that convergence towards the mean-field theory is typically slower for recurrent networks than for deep networks and the convergence speed depends non-trivially on the parameters of the weight prior as well as the depth or number of time steps, respectively. Our method exposes that Gaussian processes are but the lowest order of a systematic expansion in $1/n$. The formalism thus paves the way to investigate the fundamental differences between recurrent and deep architectures at finite widths $n$.
An Accelerator for Rule Induction in Fuzzy Rough Theory
Zhao, Suyun, Dai, Zhigang, Wang, Xizhao, Ni, Peng, Luo, Hengheng, Chen, Hong, Li, Cuiping
Rule-based classifier, that extract a subset of induced rules to efficiently learn/mine while preserving the discernibility information, plays a crucial role in human-explainable artificial intelligence. However, in this era of big data, rule induction on the whole datasets is computationally intensive. So far, to the best of our knowledge, no known method focusing on accelerating rule induction has been reported. This is first study to consider the acceleration technique to reduce the scale of computation in rule induction. We propose an accelerator for rule induction based on fuzzy rough theory; the accelerator can avoid redundant computation and accelerate the building of a rule classifier. First, a rule induction method based on consistence degree, called Consistence-based Value Reduction (CVR), is proposed and used as basis to accelerate. Second, we introduce a compacted search space termed Key Set, which only contains the key instances required to update the induced rule, to conduct value reduction. The monotonicity of Key Set ensures the feasibility of our accelerator. Third, a rule-induction accelerator is designed based on Key Set, and it is theoretically guaranteed to display the same results as the unaccelerated version. Specifically, the rank preservation property of Key Set ensures consistency between the rule induction achieved by the accelerator and the unaccelerated method. Finally, extensive experiments demonstrate that the proposed accelerator can perform remarkably faster than the unaccelerated rule-based classifier methods, especially on datasets with numerous instances.
Modeling Human-AI Team Decision Making
Ye, Wei, Bullo, Francesco, Friedkin, Noah, Singh, Ambuj K
AI and humans bring complementary skills to group deliberations. Modeling this group decision making is especially challenging when the deliberations include an element of risk and an exploration-exploitation process of appraising the capabilities of the human and AI agents. To investigate this question, we presented a sequence of intellective issues to a set of human groups aided by imperfect AI agents. A group's goal was to appraise the relative expertise of the group's members and its available AI agents, evaluate the risks associated with different actions, and maximize the overall reward by reaching consensus. We propose and empirically validate models of human-AI team decision making under such uncertain circumstances, and show the value of socio-cognitive constructs of prospect theory, influence dynamics, and Bayesian learning in predicting the behavior of human-AI groups.
Introducing Randomized High Order Fuzzy Cognitive Maps as Reservoir Computing Models: A Case Study in Solar Energy and Load Forecasting
Orang, Omid, Silva, Petrônio Cândido de Lima, Guimarães, Frederico Gadelha
Fuzzy Cognitive Maps (FCMs) have emerged as an interpretable signed weighted digraph method consisting of nodes (concepts) and weights which represent the dependencies among the concepts. Although FCMs have attained considerable achievements in various time series prediction applications, designing an FCM model with time-efficient training method is still an open challenge. Thus, this paper introduces a novel univariate time series forecasting technique, which is composed of a group of randomized high order FCM models labeled R-HFCM. The novelty of the proposed R-HFCM model is relevant to merging the concepts of FCM and Echo State Network (ESN) as an efficient and particular family of Reservoir Computing (RC) models, where the least squares algorithm is applied to train the model. From another perspective, the structure of R-HFCM consists of the input layer, reservoir layer, and output layer in which only the output layer is trainable while the weights of each sub-reservoir components are selected randomly and keep constant during the training process. As case studies, this model considers solar energy forecasting with public data for Brazilian solar stations as well as Malaysia dataset, which includes hourly electric load and temperature data of the power supply company of the city of Johor in Malaysia. The experiment also includes the effect of the map size, activation function, the presence of bias and the size of the reservoir on the accuracy of R-HFCM method. The obtained results confirm the outperformance of the proposed R-HFCM model in comparison to the other methods. This study provides evidence that FCM can be a new way to implement a reservoir of dynamics in time series modelling.
Efficiently Disentangle Causal Representations
Li, Yuanpeng, Hestness, Joel, Elhoseiny, Mohamed, Zhao, Liang, Church, Kenneth
This paper proposes an efficient approach to learning disentangled representations with causal mechanisms based on the difference of conditional probabilities in original and new distributions. We approximate the difference with models' generalization abilities so that it fits in the standard machine learning framework and can be efficiently computed. In contrast to the state-of-the-art approach, which relies on the learner's adaptation speed to new distribution, the proposed approach only requires evaluating the model's generalization ability. We provide a theoretical explanation for the advantage of the proposed method, and our experiments show that the proposed technique is 1.9-11.0 Causal reasoning is a fundamental tool that has shown significant impact in different disciplines (Rubin & Waterman, 2006; Ramsey et al., 2010; Rotmensch et al., 2017; Schölkopf et al., 2021), and it has roots in work by David Hume in the eighteenth century (Hume, 2003) and classical AI (Pearl, 2003). Causality has been mainly studied from a statistical perspective (Pearl, 2009; Peters et al., 2016; Greenland et al., 1999; Pearl, 2018) with Judea Pearl's work on the causal calculus leading its statistical development. More recently, there has been a growing interest in integrating statistical techniques into machine learning to leverage their benefits. Welling raises a particular question about how to disentangle correlation from causation in machine learning settings to take advantage of the sample efficiency and generalization abilities of causal reasoning (Welling, 2015). Although machine learning has achieved important results on a variety of tasks like computer vision and games over the past decade (e.g., Mnih et al. (2015); Silver et al. (2017); Szegedy et al. (2017); Hudson & Manning (2018)), current approaches can struggle to generalize when the test data distribution is much different from the training distribution (common in real applications). Further, these successful methods are typically "data-hungry", requiring an abundance of labeled examples to perform well across data distributions. In statistical settings, encoding the causal structure in models has been shown to have significant efficiency advantages.
Granule Description based on Compound Concepts
Zhou, Jianqin, Yang, Sichun, Wang, Xifeng, Liu, Wanquan
Concise granule descriptions for definable granules and approaching descriptions for indefinable granules are challenging and important issues in granular computing. The concept with only common attributes has been intensively studied. To investigate the granules with some special needs, we propose a novel type of compound concepts in this paper, i.e., common-and-necessary concept. Based on the definitions of concept-forming operations, the logical formulas are derived for each of the following types of concepts: formal concept, object-induced three-way concept, object oriented concept and common-and-necessary concept. Furthermore, by utilizing the logical relationship among various concepts, we have derived concise and unified equivalent conditions for definable granules and approaching descriptions for indefinable granules for all four kinds of concepts.
Gaussian Imagination in Bandit Learning
Liu, Yueyang, Devraj, Adithya M., Van Roy, Benjamin, Xu, Kuang
Assuming distributions are Gaussian often facilitates computations that are otherwise intractable. We consider an agent who is designed to attain a low information ratio with respect to a bandit environment with a Gaussian prior distribution and a Gaussian likelihood function, but study the agent's performance when applied instead to a Bernoulli bandit. We establish a bound on the increase in Bayesian regret when an agent interacts with the Bernoulli bandit, relative to an information-theoretic bound satisfied with the Gaussian bandit. If the Gaussian prior distribution and likelihood function are sufficiently diffuse, this increase grows with the square-root of the time horizon, and thus the per-timestep increase vanishes. Our results formalize the folklore that so-called Bayesian agents remain effective when instantiated with diffuse misspecified distributions.