Author name cluster

Weichen Li

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4 papers

2 author rows

AAAI Conference 2026 Conference Paper

TORA: Train Once, Realign Anytime for Offline Multi-Objective Reinforcement Learning

Weichen Li
Waleed Mustafa
Marcio Monteiro
Puyu Wang
Marius Kloft
Sophie Fellenz

Intelligent agents in real-world applications must adapt their behavior to changing contexts and user preferences. For example, planning a road trip requires considering both travel time and cost. Multi-objective reinforcement learning (MORL) provides a principled approach to navigate such trade-offs. However, most existing approaches require predefined preference weights during training and jointly optimize the model for all objectives. In this paper, we introduce TORA (Train Once, Realign Anytime), a novel framework that defers preference integration to inference time, enabling flexible adaptation to user preferences without retraining. TORA independently trains diffusion planning models for each objective and combines them at inference time using user-specified preferences to generate behavior aligned with desired trade-offs. Furthermore, new objectives can be added seamlessly by training additional models without modifying existing ones. Empirical evaluations on standard offline MORL benchmarks demonstrate that TORA achieves competitive and consistent performance compared to methods that require fixed preference weights.

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ICML Conference 2025 Conference Paper

EditLord: Learning Code Transformation Rules for Code Editing

Weichen Li
Albert Jan
Baishakhi Ray
Junfeng Yang
Chengzhi Mao
Kexin Pei

Code editing is a foundational task in software development, where its effectiveness depends on whether it introduces desired code property changes without changing the original code’s intended functionality. Existing approaches often formulate code editing as an implicit end-to-end task, omitting the fact that code-editing procedures inherently consist of discrete and explicit steps, and thus suffer from suboptimal performance and lack of robustness and generalization. We introduce EditLord, a code editing framework that makes the code transformation steps explicit. Our key insight is to employ a language model (LM) as an inductive learner to extract code editing rules from the training code pairs as concise meta-rule sets. Such rule sets will be manifested for each training sample to augment them for finetuning or assist in prompting- and iterative-based code editing. EditLord outperforms the state-of-the-art by an average of 22. 7% in editing performance and 58. 1% in robustness while achieving 20. 2% higher functional correctness, across critical software engineering and security applications, LM models, and editing modes.

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AAAI Conference 2024 Conference Paper

Beyond Entities: A Large-Scale Multi-Modal Knowledge Graph with Triplet Fact Grounding

Jingping Liu
Mingchuan Zhang
Weichen Li
Chao Wang
Shuang Li
Haiyun Jiang
Sihang Jiang
Yanghua Xiao

Much effort has been devoted to building multi-modal knowledge graphs by visualizing entities on images, but ignoring the multi-modal information of the relation between entities. Hence, in this paper, we aim to construct a new large-scale multi-modal knowledge graph with triplet facts grounded on images that reflect not only entities but also their relations. To achieve this purpose, we propose a novel pipeline method, including triplet fact filtering, image retrieving, entity-based image filtering, relation-based image filtering, and image clustering. In this way, a multi-modal knowledge graph named ImgFact is constructed, which contains 247,732 triplet facts and 3,730,805 images. In experiments, the manual and automatic evaluations prove the reliable quality of our ImgFact. We further use the obtained images to enhance model performance on two tasks. In particular, the model optimized by our ImgFact achieves an impressive 8.38% and 9.87% improvement over the solutions enhanced by an existing multi-modal knowledge graph and VisualChatGPT on F1 of relation classification. We release ImgFact and its instructions at https://github.com/kleinercubs/ImgFact.

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ICML Conference 2024 Conference Paper

Exploiting Code Symmetries for Learning Program Semantics

Kexin Pei
Weichen Li
Qirui Jin
Shuyang Liu
Scott Geng
Lorenzo Cavallaro
Junfeng Yang
Suman Jana

This paper tackles the challenge of teaching code semantics to Large Language Models (LLMs) for program analysis by incorporating code symmetries into the model architecture. We introduce a group-theoretic framework that defines code symmetries as semantics-preserving transformations, where forming a code symmetry group enables precise and efficient reasoning of code semantics. Our solution, SymC, develops a novel variant of self-attention that is provably equivariant to code symmetries from the permutation group defined over the program dependence graph. SymC obtains superior performance on five program analysis tasks, outperforming state-of-the-art code models, including GPT-4, without any pre-training. Our results suggest that code LLMs that encode the code structural prior via the code symmetry group generalize better and faster.

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