Cheshire
Fast Linear Solvers via AI-Tuned Markov Chain Monte Carlo-based Matrix Inversion
Lebedev, Anton, Lee, Won Kyung, Ghosh, Soumyadip, Yaman, Olha I., Kalantzis, Vassilis, Lu, Yingdong, Nowicki, Tomasz, Ubaru, Shashanka, Horesh, Lior, Alexandrov, Vassil
Large, sparse linear systems are pervasive in modern science and engineering, and Krylov subspace solvers are an established means of solving them. Yet convergence can be slow for ill-conditioned matrices, so practical deployments usually require preconditioners. Markov chain Monte Carlo (MCMC)-based matrix inversion can generate such preconditioners and accelerate Krylov iterations, but its effectiveness depends on parameters whose optima vary across matrices; manual or grid search is costly. We present an AI-driven framework recommending MCMC parameters for a given linear system. A graph neural surrogate predicts preconditioning speed from $A$ and MCMC parameters. A Bayesian acquisition function then chooses the parameter sets most likely to minimise iterations. On a previously unseen ill-conditioned system, the framework achieves better preconditioning with 50\% of the search budget of conventional methods, yielding about a 10\% reduction in iterations to convergence. These results suggest a route for incorporating MCMC-based preconditioners into large-scale systems.
Autonomy and Safety Assurance in the Early Development of Robotics and Autonomous Systems
Abeywickrama, Dhaminda B., Fisher, Michael, Wheeler, Frederic, Dennis, Louise
This report provides an overview of the workshop titled Autonomy and Safety Assurance in the Early Development of Robotics and Autonomous Systems, hosted by the Centre for Robotic Autonomy in Demanding and Long-Lasting Environments (CRADLE) on September 2, 2024, at The University of Manchester, UK. The event brought together representatives from six regulatory and assurance bodies across diverse sectors to discuss challenges and evidence for ensuring the safety of autonomous and robotic systems, particularly autonomous inspection robots (AIR). The workshop featured six invited talks by the regulatory and assurance bodies. CRADLE aims to make assurance an integral part of engineering reliable, transparent, and trustworthy autonomous systems. Key discussions revolved around three research questions: (i) challenges in assuring safety for AIR; (ii) evidence for safety assurance; and (iii) how assurance cases need to differ for autonomous systems. Following the invited talks, the breakout groups further discussed the research questions using case studies from ground (rail), nuclear, underwater, and drone-based AIR. This workshop offered a valuable opportunity for representatives from industry, academia, and regulatory bodies to discuss challenges related to assured autonomy. Feedback from participants indicated a strong willingness to adopt a design-for-assurance process to ensure that robots are developed and verified to meet regulatory expectations.
Britain's pothole hotspots: Interactive map reveals the areas where roads are worst blighted by craters - so, how does your hometown stack up?
For drivers who endure Britain's crumbling roads daily, there's no doubt we're stuck in an escalating'pothole crisis'. These dangerous holes can injure and even kill cyclists and motorists, and are popping up quicker than they can be filled. Now, interactive graphics reveal the shocking extent of the problem - and scientists think climate change is to blame. Climate organisation Round our Way reveals 952,064 potholes were reported in Britain between January and November last year, marking a five-year high. MailOnline's interactive map, based on the new data, reveals the local authorities with the most pothole reports during the period.
'Sickening' Molly Russell and Brianna Ghey AI chatbots are found on controversial Character.ai site
AI chatbots impersonating Molly Russell and Brianna Ghey have been found on the controversial site Character.ai. Brianna Ghey was murdered by two teenagers in 2023 while Molly Russell took her own life at the age of 14 after viewing self-harm-related content on social media. In an act described as'sickening', the site's users employed the girl's names, pictures, and biographical details to create dozens of automated bots. Despite violating the site's terms of service, these imitation avatars posing as the two girls were allowed to amass thousands of chats. One impersonating Molly Russell even claimed to be an'expert on the final years of Molly's life'.
HOLMES: Hyper-Relational Knowledge Graphs for Multi-hop Question Answering using LLMs
Panda, Pranoy, Agarwal, Ankush, Devaguptapu, Chaitanya, Kaul, Manohar, P, Prathosh A
Given unstructured text, Large Language Models (LLMs) are adept at answering simple (single-hop) questions. However, as the complexity of the questions increase, the performance of LLMs degrade. We believe this is due to the overhead associated with understanding the complex question followed by filtering and aggregating unstructured information in the raw text. Recent methods try to reduce this burden by integrating structured knowledge triples into the raw text, aiming to provide a structured overview that simplifies information processing. However, this simplistic approach is query-agnostic and the extracted facts are ambiguous as they lack context. To address these drawbacks and to enable LLMs to answer complex (multi-hop) questions with ease, we propose to use a knowledge graph (KG) that is context-aware and is distilled to contain query-relevant information. The use of our compressed distilled KG as input to the LLM results in our method utilizing up to $67\%$ fewer tokens to represent the query relevant information present in the supporting documents, compared to the state-of-the-art (SoTA) method. Our experiments show consistent improvements over the SoTA across several metrics (EM, F1, BERTScore, and Human Eval) on two popular benchmark datasets (HotpotQA and MuSiQue).
Adaptive Primal-Dual Method for Safe Reinforcement Learning
Chen, Weiqin, Onyejizu, James, Vu, Long, Hoang, Lan, Subramanian, Dharmashankar, Kar, Koushik, Mishra, Sandipan, Paternain, Santiago
Primal-dual methods have a natural application in Safe Reinforcement Learning (SRL), posed as a constrained policy optimization problem. In practice however, applying primal-dual methods to SRL is challenging, due to the inter-dependency of the learning rate (LR) and Lagrangian multipliers (dual variables) each time an embedded unconstrained RL problem is solved. In this paper, we propose, analyze and evaluate adaptive primal-dual (APD) methods for SRL, where two adaptive LRs are adjusted to the Lagrangian multipliers so as to optimize the policy in each iteration. We theoretically establish the convergence, optimality and feasibility of the APD algorithm. Finally, we conduct numerical evaluation of the practical APD algorithm with four well-known environments in Bullet-Safey-Gym employing two state-of-the-art SRL algorithms: PPO-Lagrangian and DDPG-Lagrangian. All experiments show that the practical APD algorithm outperforms (or achieves comparable performance) and attains more stable training than the constant LR cases. Additionally, we substantiate the robustness of selecting the two adaptive LRs by empirical evidence.
Variational Exploration Module VEM: A Cloud-Native Optimization and Validation Tool for Geospatial Modeling and AI Workflows
Kuehnert, Julian, Tadesse, Hiwot, Dearden, Chris, Lickorish, Rosie, Fraccaro, Paolo, Jones, Anne, Edwards, Blair, Remy, Sekou L., Melling, Peter, Culmer, Tim
Geospatial observations combined with computational models have become key to understanding the physical systems of our environment and enable the design of best practices to reduce societal harm. Cloud-based deployments help to scale up these modeling and AI workflows. Yet, for practitioners to make robust conclusions, model tuning and testing is crucial, a resource intensive process which involves the variation of model input variables. We have developed the Variational Exploration Module which facilitates the optimization and validation of modeling workflows deployed in the cloud by orchestrating workflow executions and using Bayesian and machine learning-based methods to analyze model behavior. User configurations allow the combination of diverse sampling strategies in multi-agent environments. The flexibility and robustness of the model-agnostic module is demonstrated using real-world applications.
Quantifying the value of information transfer in population-based SHM
Hughes, Aidan J., Poole, Jack, Dervilis, Nikolaos, Gardner, Paul, Worden, Keith
Population-based structural health monitoring (PBSHM), seeks to address some of the limitations associated with data scarcity that arise in traditional SHM. A tenet of the population-based approach to SHM is that information can be shared between sufficiently-similar structures in order to improve predictive models. Transfer learning techniques, such as domain adaptation, have been shown to be a highly-useful technology for sharing information between structures when developing statistical classifiers for PBSHM. Nonetheless, transfer-learning techniques are not without their pitfalls. In some circumstances, for example if the data distributions associated with the structures within a population are dissimilar, applying transfer-learning methods can be detrimental to classification performance -- this phenomenon is known as negative transfer. Given the potentially-severe consequences of negative transfer, it is prudent for engineers to ask the question `when, what, and how should one transfer between structures?'. The current paper aims to demonstrate a transfer-strategy decision process for a classification task for a population of simulated structures in the context of a representative SHM maintenance problem, supported by domain adaptation. The transfer decision framework is based upon the concept of expected value of information transfer. In order to compute the expected value of information transfer, predictions must be made regarding the classification (and decision performance) in the target domain following information transfer. In order to forecast the outcome of transfers, a probabilistic regression is used here to predict classification performance from a proxy for structural similarity based on the modal assurance criterion.
Cost-Effective Hyperparameter Optimization for Large Language Model Generation Inference
Wang, Chi, Liu, Susan Xueqing, Awadallah, Ahmed H.
Large Language Models (LLMs) have sparked significant interest in their generative capabilities, leading to the development of various commercial applications. The high cost of using the models drives application builders to maximize the value of generation under a limited inference budget. This paper presents a study of optimizing inference hyperparameters such as the number of responses, temperature and max tokens, which significantly affects the utility/cost of text generation. We design a framework named EcoOptiGen which leverages economical hyperparameter optimization and cost-based pruning. Experiments with the GPT-3.5/GPT-4 models on a variety of tasks verify its effectiveness. EcoOptiGen is implemented in the `autogen' package of the FLAML library: \url{https://aka.ms/autogen}.
A decision framework for selecting information-transfer strategies in population-based SHM
Hughes, Aidan J., Poole, Jack, Dervilis, Nikolaos, Gardner, Paul, Worden, Keith
Unfortunately, the limited availability of labelled training data hinders the development of the statistical models on which these decision-support systems rely. Population-based SHM seeks to mitigate the impact of data scarcity by using transfer learning techniques to share information between individual structures within a population. The current paper proposes a decision framework for selecting transfer strategies based upon a novel concept - the expected value of information transfer - such that negative transfer is avoided. By avoiding negative transfer, and by optimising information transfer strategies using the transfer-decision framework, one can reduce the costs associated with operating and maintaining structures, and improve safety. INTRODUCTION Structural health monitoring (SHM) systems provide a means of augmenting operation and maintenance decision processes with up-to-date information regarding the health-state of a structure or system [1]. In order to assign features extracted from sensor data to meaningful categories in the context of the decision process (e.g.