Robust Shunting in a Dynamic Environment: Deriving Proactive Schedules from a Reactive Policy

When trains are not actively traveling on the main rail network, they to be parked and prepared for their next journey. This is a complex problem, involving several interconnected subproblems. Additionally, there is uncertainty in this environment which can render initial plans infeasible during their execution. To ensure trains are able to...

Elastic gradient boosting decision trees under limited labels by sequential epistemic uncertainty quantification: Elastic CatBoost Uncertainty (eCBU)

Intrusion detection systems (IDSs) are essential for protecting computer systems and networks from malicious attacks. However, IDSs face challenges in dealing with dynamic and imbalanced data, as well as limited label availability. In this thesis, we propose a novel elastic gradient boosting decision tree algorithm, namely Elastic CatBoost...

VoBERT: Unstable Log Sequence Anomaly Detection: Introducing Vocabulary-Free BERT

With the ever-increasing digitalisation of society and the explosion of internet-enabled devices with the Internet of Things (IoT), keeping services and devices secure is becoming more important. Logs play a critical role in sustaining system reliability. Manual analysis of logs has become increasingly difficult, accelerating the development of...

Combining Multi-Objective Planning with Reinforcement Learning to Solve Complex Tasks in Environments with Sparse Rewards

Sequential decision-making problems are problems where the goal is to find a sequence of actions that complete a task in an environment. A particularly difficult type of sequential decision-making problem to solve is one in which the environment has sparse rewards, a large state space, and where the goal is to complete a complex task. In this...

Interpretability and performance of surrogate decision trees produced by Viper

Machine learning models are being used extensively in many high impact scenarios. Many of these models are ‘black boxes’, which are almost impossible to interpret. Successful implementations have been limited by this lack of interpretability. One approach to increasing interpretability is to use imitation learning to extract a more interpretable...

Using Decision Trees produced by Generative Adversarial Imitation Learning to give insight into black box Reinforcement Learning models

Machine learning models are increasingly being used in fields that have a direct impact on the lives of humans. Often these machine learning models are black-box models and they lack transparency and trust which is holding back the implementation. To increase transparency and trust this research investigates whether imitation learning,...

Interpretability and performance comparisons of decision tree surrogate models produced by AGGREVATE

Imitation learning algorithms, such as AggreVaTe, have proven successful in solving many challenging tasks accurately and efficiently. In practice, however, they have not been applied quite as much. Black box policies produced by imitation learning algorithms can not ensure the safety needed for real-world applications. This paper extends this...