Lihao Liu
Author directory2026
ESPO: Error-Structured Prompt Optimization via Diagnose, Diversify, and Stabilize
Lihao Liu | Peng Tang | Kunwar Yashraj Singh | Shabnam Ghadar
Findings of the Association for Computational Linguistics: EMNLP 2026
Lihao Liu | Peng Tang | Kunwar Yashraj Singh | Shabnam Ghadar
Findings of the Association for Computational Linguistics: EMNLP 2026
Evolutionary prompt optimizers such as GEPA suffer from prompt bloat: each iteration appends rules and caveats, producing prompts that are 2–3× longer yet no more accurate. We trace this to three deficiencies - incomplete error observation, limited search diversity, and unreliable selection - and propose ESPO (Error-Structured Prompt Optimization), which decomposes prompt optimization into three phases: Diagnose clusters all training errors into structural patterns in one round; Propose generates candidates via four complementary strategies with independent biases; Select applies bootstrap stability selection. On seven public NLP benchmarks - Tweet, MMLU, GSM8K, HotpotQA, ScoNe, HoVer, and PUPA - ESPO wins 6/7 datasets with +3.76% average accuracy over the state-of-the-art (74.67% vs. 70.91% for GEPA), while producing prompts 47% shorter (1,004 vs. 1,878 chars) and faster at inference. Cross-model experiments across four additional student models (Gemma 3 12B, Mistral 14B, Qwen3 32B, Claude Haiku 4.5) show ESPO yields the best average accuracy on every model tested, with the largest gap on Qwen3 GSM8K (15.00% → 91.40%). A generalization bound (Appendix) grounds each phase in a corresponding term of the test-time gap, and the ablation confirms a key prediction: adding diversity without bootstrap selection actually hurts performance (-1.20%).
THE-Tree: Can Tracing Historical Evolution Enhance Scientific Verification and Reasoning?
Xin Wang | Jiyao Liu | Yulong Xiao | Junzhi Ning | Hairong Zhang | Lihao Liu | Junjun He | Botian Shi | Kaicheng Yu
Findings of the Association for Computational Linguistics: EMNLP 2026
Xin Wang | Jiyao Liu | Yulong Xiao | Junzhi Ning | Hairong Zhang | Lihao Liu | Junjun He | Botian Shi | Kaicheng Yu
Findings of the Association for Computational Linguistics: EMNLP 2026
Large Language Models (LLMs) are accelerating scientific idea generation, but rigorously evaluating these numerous, often superficial, AI-generated propositions for novelty and factual accuracy is a critical bottleneck; manual verification is too slow. Existing validation methods are inadequate: LLMs as standalone verifiers may hallucinate and lack domain knowledge (our findings show ~60% unawareness of relevant papers in specific domains), while traditional citation networks lack explicit causality and narrative surveys are unstructured. This underscores a core challenge: the absence of structured, verifiable, and causally-linked historical data of scientific evolution. To address this, we introduce THE-Tree (Technology History Evolution Tree), a computational framework that constructs such domain-specific evolution trees from scientific literature. THE-Tree employs a search algorithm to explore evolutionary paths. During its node expansion, it utilizes a novel "Think-Verbalize-Cite-Verify" process: an LLM proposes potential advancements and cites supporting literature. Critically, each proposed evolutionary link is then validated for logical coherence and evidential support by a recovered natural language inference mechanism that interrogates the cited literature, ensuring that each step is grounded. We construct and validate 88 THE-Trees across diverse domains and release a benchmark dataset including up to 71k fact verifications covering 27k papers to foster further research. Experiments demonstrate that i) in graph completion, our THE-Tree improves hit@1 by 8% to 14% across multiple models compared to traditional citation networks; ii) for predicting future scientific developments, it improves hit@1 metric by nearly 10%; and iii) when combined with other methods, it boosts the performance of evaluating important scientific papers by almost 100%. By constructing explicit, verifiable pathways of scientific progression, THE-Tree provides a robust historical foundation for evaluating new hypotheses (human or AI-generated) and enables a computable science history, fostering evidence-based AI-driven scientific discovery.
Can MLLMs Perceive and Describe Medical Image Quality Beyond Scores?
Jiyao Liu | Jinjie Wei | Wanying Qu | Chenglong Ma | Junzhi Ning | Yunheng Li | Ying Chen | Jiafan Zhang | Pengcheng Chen | Xin Gao | Ming Hu | Xin Wang | Shujian Gao | Dingkang Yang | Zhongying Deng | Jin Ye | Lihao Liu | Junjun He | Ningsheng Xu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Jiyao Liu | Jinjie Wei | Wanying Qu | Chenglong Ma | Junzhi Ning | Yunheng Li | Ying Chen | Jiafan Zhang | Pengcheng Chen | Xin Gao | Ming Hu | Xin Wang | Shujian Gao | Dingkang Yang | Zhongying Deng | Jin Ye | Lihao Liu | Junjun He | Ningsheng Xu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Medical Image Quality Assessment (IQA) serves as a critical safety gate for clinical AI, yet existing approaches rely on scalar metrics that fail to capture the descriptive, expert-like evaluation process central to clinical practice. We introduce MedQ-Bench, a comprehensive benchmark for language-based medical IQA evaluation with MLLMs, establishing a perception–description paradigm across 5 imaging modalities and over 40 quality attributes. The benchmark comprises two complementary tasks: MedQ-Perception probes low-level visual attribute discrimination via 2,600 expert-annotated perceptual queries; MedQ-Description covers both no-reference and comparison description sub-tasks with 708 expert-annotated samples, evaluated through a four-dimensional judging protocol. Comprehensive evaluation of 23 state-of-the-art MLLMs reveals that current models exhibit only preliminary and unstable capabilities, and highlights the urgent need for targeted optimization of MLLMs in medical IQA. Project Dataset: https://github.com/liujiyaoFDU/MedQ-Bench