Research

I'm especially interested in several fundamental problems in machine learning:
1. Decision Invariant Optimization (Xcurve Framework)
2. Trustworthy Machine Learning
3. Long-tail Learning
  • Decision Invariant Optimization (Xcurve Framework)

    Recently, machine learning and deep learning technologies have been successfully employed in many complicated high-stake decision-making applications such as disease prediction, fraud detection, outlier detection, and criminal justice sentencing. All these applications share a common trait known as risk-aversion in economics and finance terminologies. In other words, the decision-makers tend to have an extremely low risk tolerance. Under this context, the decision-makers will carefully choose their decision parameter to meet the specific requirement. Consequently, the decision parameters for train- and test- might be quite different. To mitigate the decision parameter shift problem, I'm seeking for new decision-invariant machine learning machanisms , on top of which we develop a new framework called Xcurve

    The goal of X-curve learning is to learn high-quality models that can adapt to different decision conditions. Inspired by the fundamental principle of the well-known AUC optimization, our library provides a systematic solution to optimize the area under different kinds of performance curves. To be more specific, the performance curve is formed by a plot of two performance functions $x(\lambda)$, $y(\lambda)$ of decision parameter $\lambda$. The area under a performance curve becomes the integral of the performance over all possible choices of different decision conditions. In this way, the learning systems are only required to optimize a decision-invariant metric to avoid the risk aversion issue

    Four Kinds of Performance Curves

    • AUROC
      • Partial performance constraints (only focus on subset of TPR, FPR)
          1. When All We Need is a Piece of the Pie: A Generic Framework for Optimizing Two-way Partial AUC
            Zhiyong Yang , Qianqian Xu, Shilong Bao, and 3 more authors
            International Conference on Machine Learning,  2021
                      1. Optimizing Two-way Partial AUC with an End-to-end Framework
                        Zhiyong Yang , Qianqian Xu, Shilong Bao, and 3 more authors
                        IEEE Transactions on Pattern Analysis and Machine Intelligence,  2022
                                        1. Asymptotically Unbiased Instance-wise Regularized Partial AUC Optimization: Theory and Algorithm
                                          Huiyang Shao, Qianqian Xu, Zhiyong Yang , and 2 more authors
                                          Advances in Neural Information Processing Systems,  2022
                                                1. Multiclass extension
                                                  1. Learning with Multiclass AUC: Theory and Algorithms
                                                    Zhiyong Yang , Qianqian Xu, Shilong Bao, and 2 more authors
                                                    IEEE Transactions on Pattern Analysis and Machine Intelligence,  2021
                                                              1. Generalized AUC with non-uniform cost/threshold distribution
                                                                    1. Weighted ROC Curve in Cost Space: Extending AUC to Cost-Sensitive Learning
                                                                      Huiyang Shao, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                      Advances in Neural Information Processing Systems,  2023
                                                                            1. AUROC-inspired metric learning
                                                                              1. Rethinking Label Flipping Attack: From Sample Masking to Sample Thresholding
                                                                                Qianqian Xu, Zhiyong Yang , Yunrui Zhao, and 2 more authors
                                                                                IEEE Transactions on Pattern Analysis and Machine Intelligence,  2022
                                                                                                1. The Minority Matters: A Diversity-Promoting Collaborative Metric Learning Algorithm
                                                                                                  Shilong Bao, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                                                  Advances in Neural Information Processing Systems,  2022
                                                                                                      1. AUPRC
                                                                                                        • List
                                                                                                              1. Exploring the Algorithm-Dependent Generalization of AUPRC Optimization with List Stability
                                                                                                                Peisong Wen, Qianqian Xu, Zhiyong Yang , and 2 more authors
                                                                                                                Advances in Neural Information Processing Systems,  2022
                                                                                                                    1. AUTKC (Performance-Curve Metric for Top-K Classification)
                                                                                                                      • List
                                                                                                                        1. Optimizing Partial Area Under the Top-k Curve: Theory and Practice
                                                                                                                          Zitai Wang, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                                                                          IEEE Transactions on Pattern Analysis and Machine Intelligence,  2022
                                                                                                                                  1. OpenAUC (Performance-Curve Metric for OOD Learning)
                                                                                                                                    • List
                                                                                                                                          1. OpenAUC: Towards AUC-Oriented Open-Set Recognition
                                                                                                                                            Zitai Wang, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                                                                                            Advances in Neural Information Processing Systems,  2022
                                                                                                                                              1. Trustworthy Machine Learning

                                                                                                                                                We are seeking for new principled method to make the current machine learning system trustworthy (e.g. Robustness against Adversarial attacks, OOD examples). On top of Xcurve, I'm especially interested in (a) how to design performance-based metrics for trustworthy machine learning, and (b) how to use the SOTA models and idea of trustworthy machine learning to improve the Xcurve Framework.

                                                                                                                                                • Adversarial Robustness for Xcurve
                                                                                                                                                  • List
                                                                                                                                                      1. AdAUC: End-to-end Adversarial AUC Optimization Against Long-tail Problems
                                                                                                                                                        Wenzheng Hou, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                                                                                                        International Conference on Machine Learning,  2022
                                                                                                                                                                  1. Revisiting AUC-oriented Adversarial Training with Loss-Agnostic Perturbations
                                                                                                                                                                    Zhiyong Yang , Qianqian Xu, Wenzheng Hou, and 4 more authors
                                                                                                                                                                    IEEE Transactions on Pattern Analysis and Machine Intelligence,  2023
                                                                                                                                                                            1. Domain Adaptation for Xcurve
                                                                                                                                                                              • List
                                                                                                                                                                                1. AUC-Oriented Domain Adaptation: From Theory to Algorithm
                                                                                                                                                                                  Zhiyong Yang , Qianqian Xu, Shilong Bao, and 4 more authors
                                                                                                                                                                                  IEEE Transactions on Pattern Analysis and Machine Intelligence,  2023
                                                                                                                                                                                          1. Xcurve Metrics for Openset Recognition
                                                                                                                                                                                            • List
                                                                                                                                                                                                  1. OpenAUC: Towards AUC-Oriented Open-Set Recognition
                                                                                                                                                                                                    Zitai Wang, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                                                                                                                                                    Advances in Neural Information Processing Systems,  2022
                                                                                                                                                                                                      1. Long-tail Learning

                                                                                                                                                                                                        Long-tail learning is one of the most challenging problems in machine learning, which aims to train well-performing models from a large number of examples that follow a highly imbalanced class distribution. We find that the long-tail problem could be mitigated by adjusting the optimal decision rule. On top of the Xcurve framework, we are interested in (a) how to design distribution-invariant metrics for long-tail learning to deal with different long-tail distributions, and (b) how to directly optimize such metrics efficiently.

                                                                                                                                                                                                        • Long-tail Learning
                                                                                                                                                                                                          • List
                                                                                                                                                                                                                1. A Unified Generalization Analysis of Re-Weighting and Logit-Adjustment for Imbalanced Learning
                                                                                                                                                                                                                  Zitai Wang, Qianqian Xu, Zhiyong Yang , and 3 more authors
                                                                                                                                                                                                                  Advances in Neural Information Processing Systems,  2023
                                                                                                                                                                                                                          1. Learning with Multiclass AUC: Theory and Algorithms
                                                                                                                                                                                                                            Zhiyong Yang , Qianqian Xu, Shilong Bao, and 2 more authors
                                                                                                                                                                                                                            IEEE Transactions on Pattern Analysis and Machine Intelligence,  2021
                                                                                                                                                                                                                                          1. When All We Need is a Piece of the Pie: A Generic Framework for Optimizing Two-way Partial AUC
                                                                                                                                                                                                                                            Zhiyong Yang , Qianqian Xu, Shilong Bao, and 3 more authors
                                                                                                                                                                                                                                            International Conference on Machine Learning,  2021