Liu Leqi
Author directory2026
PragReST: Self-Reinforcing Counterfactual Reasoning for Pragmatic Language Understanding
Jihyung Park | Minchao Huang | Liu Leqi | Elias Stengel-Eskin
Findings of the Association for Computational Linguistics: EMNLP 2026
Jihyung Park | Minchao Huang | Liu Leqi | Elias Stengel-Eskin
Findings of the Association for Computational Linguistics: EMNLP 2026
Natural language understanding often depends on meanings that are implied rather than explicitly stated, requiring pragmatic reasoning. Despite strong performance on math and logical reasoning, large language models (LLMs) still trail humans on pragmatic inference, often defaulting to literal interpretations. To improve LLM pragmatic reasoning, we introduce PragReST, a self-supervised framework that constructs pragmatic QA data, generates counterfactual reasoning traces, and trains models to internalize them through supervised fine-tuning and reinforcement learning, without human-labeled training data or distillation from a stronger teacher. Across four pragmatic benchmarks (PRAGMEGA, LUDWIG, METOQA, and ALTPRAG) and multiple model families, including Qwen3, Gemma, and GPT-OSS, PragReST consistently improves over backbone models, task-specific pragmatic tuning baselines, and non-counterfactual variants of the same pipeline. On accuracy-based benchmarks, PragReST improves over the instruct backbone by 5.37% and 5.50% (absolute) for Qwen3-8B and Qwen3-14B, respectively. Our error analysis and ablations underscore the importance of counterfactual reasoning: PragReST primarily reduces errors caused by failures to contrast observed utterances with plausible alternatives, and removing counterfactual reasoning substantially reduces performance. Moreover, our training preserves out-of-domain performance on general-knowledge and mathematical reasoning benchmarks.
Learning Composable Chains-of-Thought
Fangcong Yin | Zeyu Leo Liu | Liu Leqi | Xi Ye | Greg Durrett
Findings of the Association for Computational Linguistics: EMNLP 2026
Fangcong Yin | Zeyu Leo Liu | Liu Leqi | Xi Ye | Greg Durrett
Findings of the Association for Computational Linguistics: EMNLP 2026
A common approach for teaching large language models (LLMs) to reason is to train on chains-of-thought (CoTs) of in-distribution reasoning problems. However, such annotated data is costly to obtain for every problem of interest. We want reasoning models to generalize beyond their training distribution, and ideally to generalize compositionally: they should combine atomic reasoning skills to solve harder unseen tasks. In this paper, we introduce a method to enable generalization to a target compositional task that has no labeled CoT data. We minimally modify CoT formats of constituent atomic tasks to be composable: we add prefixes to CoTs during training time, thereby encouraging the trained model to generate sequences of CoTs during inference. We train individual models on the atomic tasks with composable CoT data and combine them with multitask learning or model merging to address the target compositional task zero-shot. This model can be further trained on a small amount of compositional data using rejection sampling fine-tuning (RFT). Training LLMs on Composable CoT outperforms multitask learning and continued fine-tuning baselines on three domains of controlled compositional tasks and also yields improvement on math skill composition setting derived from the MATH dataset.
2025
The Progress Illusion: Revisiting meta-evaluation standards of LLM evaluators
Tianruo Rose Xu | Vedant Gaur | Liu Leqi | Tanya Goyal
Findings of the Association for Computational Linguistics: EMNLP 2025
Tianruo Rose Xu | Vedant Gaur | Liu Leqi | Tanya Goyal
Findings of the Association for Computational Linguistics: EMNLP 2025
LLM judges have gained popularity as an inexpensive and performant substitute for human evaluation. However, we observe that the meta-evaluation setting in which the reliability of these LLM evaluators is established is substantially different from their use in model development. To address this, we revisit meta-evaluations of LLM evaluators under a setting that more closely aligns with practice by examining evaluators’ ability to distinguish test system pairs that are closer in capability. Our fine-grained approach shows that all LLM evaluator’s correlations with human judgments are concerningly low when the models perform similarly, showcasing a key limitation of current norms. Equipped with this better methodology, we next analyze the impact that the choice of the reference model makes to LLM-as-a-judge evaluator performance. We show that single-reference evaluators only perform well at ranking test systems that fall within particular capability ranges, even if the standard meta-evaluation reports high overall correlation. Taken together, our analysis shows critical issues with current LLM meta-evaluation and recommend avenues for improvement.