Large language models (LLMs) still produce plausible-sounding but ungrounded factual claims, a problem that worsens in multi-turn dialogue as context grows and early errors cascade. We introduce $\textbf{HalluHard}$, a challenging multi-turn hallucination benchmark with 950 seed questions spanning four high-stakes domains: legal cases, research questions, medical guidelines, and coding. We operationalize groundedness by requiring inline citations for factual assertions. To support reliable evaluation in open-ended settings, we propose a judging pipeline that iteratively retrieves evidence via web search. It can fetch, filter, and parse full-text sources (including PDFs) to assess whether cited material actually supports the generated content. Across a diverse set of frontier proprietary and open-weight models, hallucinations remain substantial even with web search ($\approx 30\%$ for the strongest configuration, Opus-4.5 with web search), with content-grounding errors persisting at high rates. Finally, we show that hallucination behavior is shaped by model capacity, turn position, effective reasoning, and the type of knowledge required.
Micro-Macro Retrieval: Reducing Long-Form Hallucination in Large Language Models
Solar System of OVB, Tencent, China(OVB太阳系,腾讯,中国);The Hong Kong Polytechnic University, Hong Kong S.A.R.(香港理工大学,香港特别行政区);Jilin University, China(吉林大学,中国)
AgentHallu: Benchmarking Automated Hallucination Attribution of LLM-based Agents
Beijing University of Posts and Telecommunications(北京邮电大学);Department of Computer Science & Technology, Tsinghua University(清华大学计算机科学与技术系);University of California, Santa Barbara(加州大学圣芭芭拉分校);Center for Research on Intelligent Perception and Computing, NLPR, CASIA(智能感知与计算研究中心,国家工程实验室)
5ting at SemEval-2026 Task 8: Strong End-to-End Multi-Turn RAG via LLM-Based Reranking and Faithfulness Control
University of Information Technology, Ho Chi Minh City, Vietnam(信息技术大学,胡志明市,越南);Vietnam National University Ho Chi Minh City, Ho Chi Minh City, Vietnam(越南胡志明市国家大学,胡志明市,越南)
TriLens: Per-Layer Logit-Lens Entropy for White-Box Hallucination Detection
Binjiang Institute of Zhejiang University(浙江大学滨海学院);Beijing Normal-Hong Kong Baptist University(北京师范大学-香港 Baptist大学);Zhejiang University(浙江大学);GenTel.io;Great Bay University(Great Bay大学)
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology(麻省理工学院电子工程与计算机科学系);MIT-IBM Watson AI Lab(MIT-IBM沃森人工智能实验室);IBM Research(IBM研究院)
Reading Between the Lines: The One-Sided Conversation Problem
Paul G. Allen School of Computer Science & Engineering, University of Washington(保罗·G·阿伦计算机科学与工程学院,华盛顿大学);Allen Institute for Artificial Intelligence(阿伦人工智能研究所);Hearvana AI
Evaluating Multi-Turn Multimodal Diagnostic Reasoning on Challenging Real-World Clinical Cases
Center for Biomedical Data Science, Duke-NUS Medical School(生物医学数据科学中心,杜克 - 新加坡国立大学医学院);Duke-NUS AI + Medical Sciences Initiative, Duke-NUS Medical School(杜克 - 新加坡国立大学人工智能与医学科学计划,杜克 - 新加坡国立大学医学院);Department of Population Health Sciences, Weill Cornell Medicine(人口健康科学系,威尔康奈尔医学院);System Engineering, College of Engineering, Cornell University(系统工程,康奈尔大学工程学院);Graduate School of Frontier Sciences, The University of Tokyo(前沿科学研究生院,东京大学);RIKEN Center for Advanced Intelligence Project(理化学研究所先进智能项目中心);Department of Biostatistics and Bioinformatics, Duke University(生物统计学与生物信息学系,杜克大学);Perelman School of Medicine, University of Pennsylvania(佩雷尔曼医学院,宾夕法尼亚大学);School of Clinical Medicine, University of Cambridge(临床医学学院,剑桥大学);Hospital of the University of Pennsylvania(宾夕法尼亚大学医院);Children’s Hospital of Philadelphia (CHOP)(费城儿童医院);Department of Anatomic Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania(解剖病理学与检验医学系,宾夕法尼亚大学医院);Department of Pathology and Laboratory Medicine, University of California, San Francisco(病理学与检验医学系,加州大学旧金山分校);Language Technologies Institute, Carnegie Mellon University(语言技术研究所,卡内基梅隆大学)
Key Laboratory of High Confidence Software Technologies, CS, Peking University, China(高可信软件技术重点实验室,中国科学院,北京大学);Theory Lab, Central Research Institute, 2012 Labs, Huawei Technologies Co., Ltd, Shenzhen, China(理论实验室,中央研究院,2012实验室,华为技术有限公司,深圳)
AI-Salesman: Towards Reliable Large Language Model Driven Telemarketing
Chinese Information Processing Laboratory, Institute of Software, Chinese Academy of Sciences(中国科学院软件研究所中文信息处理实验室);University of Chinese Academy of Sciences(中国科学院大学)
AnchorSIPS: A Synthetic Dataset and Evaluation Resource for Evidence-Supported Psychosis-Risk Symptom Measurement
Monash University(莫纳什大学);Orygen(奥瑞金);The University of Melbourne(墨尔本大学);Swinburne University of Technology(斯威本科技大学);University of Liverpool(利物浦大学);Khalifa University(哈利法大学)
RhinoInsight: Improving Deep Research through Control Mechanisms for Model Behavior and Context
DeepLang AI;Department of Computer Science and Technology, Tsinghua University(计算机科学与技术系,清华大学);Beijing University of Posts and Telecommunications(北京邮电大学);Beijing Jiaotong University(北京交通大学)