Weihao Sun

Yanzhi Chen, Weihao Sun, Yingzhen Li et al. · cambridge

The task of infomin learning aims to learn a representation with high utility while being uninformative about a specified target, with the latter achieved by minimising the mutual information between the representation and the target. It has broad applications, ranging from training fair prediction models against protected attributes, to unsupervised learning with disentangled representations. Recent works on infomin learning mainly use adversarial training, which involves training a neural network to estimate mutual information or its proxy and thus is slow and difficult to optimise. Drawing on recent advances in slicing techniques, we propose a new infomin learning approach, which uses a novel proxy metric to mutual information. We further derive an accurate and analytically computable approximation to this proxy metric, thereby removing the need of constructing neural network-based mutual information estimators. Experiments on algorithmic fairness, disentangled representation learning and domain adaptation verify that our method can effectively remove unwanted information with limited time budget.

Weihao Sun, Qiyun Zhao

The Just-In-Time (JIT) defect prediction model serves as a critical tool for ensuring the quality of software development and enhancing software performance. It assists development teams in promptly identifying and addressing potential issues by predicting whether code submissions may introduce defects. However, due to the existence of data noise and insufficient semantic connections in real-world scenarios, existing approaches face challenges in accurately identifying the code commits that introduce defects and capturing the potential semantic relationships. To address these challenges, we propose the BIC- Hunter(Bug-Inducing Commits Hunter) model, which mitigates data noise and improves semantic understanding, thereby enhancing the accuracy of bug-inducing commit identification. BIC - Hunter model consists of two components: a data denoising component and a semantic relationship capturing component. Specifically, the data denoising component addresses the challenges posed by inaccurate annotations and inconsistencies in real-world data, enhancing the reliability of training data and improving overall model robustness. The semantic relation- ship capturing component constructs homogeneous graphs and applies graph convolutional networks to facilitate a more comprehensive analysis of code context, enabling the identification of defects caused by code commits and enhancing the confidence in pinpointing their root causes. Experimental studies on a large-scale dataset integrated from three open-source datasets show that BIC- Hunter exhibits outstanding performance. BIC- Hunter outperforms the state-of-the-art by 6.16%, 7.13%, and 5.53% on Recall@1, Recall@2, and Recall@3, respectively, while the MFR index increases by 8.43% to 32.82%. These results demonstrate the superior capability of our method in identifying bug-inducing commits.

Weihao Sun, Gehui Xu, Alessio Moreschini et al.

In this paper, we develop a kernel-based policy iteration functional learning framework for computing team-optimal strategies in traffic coordination problems. We consider a multi-agent discrete-time linear system with a cost function that combines quadratic regulation terms and nonlinear safety penalties. Building on the Hilbert space formulation of offline receding-horizon policy iteration, we seek approximate solutions within a reproducing kernel Hilbert space, where the policy improvement step is implemented via a discrete Fréchet derivative. We further study the model-free receding-horizon scenario, where the system dynamics are estimated using recursive least squares, followed by updating the policy using rolling online data. The proposed method is tested in signal-free intersection scenarios via both model-based and model-free simulations and validated in SUMO.

Shanting Wang, Weihao Sun, Andreas A. Malikopoulos

In this paper, we present an online learning approach for two-player zero-sum linear quadratic games with unknown dynamics. We develop a framework combining regularized least squares model estimation, high probability confidence sets, and surrogate model selection to maintain a regular model for policy updates. We apply a shrinkage step at each episode to identify a surrogate model in the region where the generalized algebraic Riccati equation admits a stabilizing saddle point solution. We then establish regret analysis on algorithm convergence, followed by a numerical example to illustrate the convergence performance and verify the regret analysis.

Weihao Sun, Heeseung Bang, Andreas A. Malikopoulos

In this paper, we present an adherence-aware reinforcement learning (RL) approach aimed at seeking optimal lane-changing recommendations within a semi-autonomous driving environment to enhance a single vehicle's travel efficiency. The problem is framed within a Markov decision process setting and is addressed through an adherence-aware deep Q network, which takes into account the partial compliance of human drivers with the recommended actions. This approach is evaluated within CARLA's driving environment under realistic scenarios.