

The 64th Annual Meeting of the Association for Computational Linguistics (ACL) is underway in San Diego, followed next week by the Forty-Third International Conference on Machine Learning (ICML) in Seoul, South Korea. We’re excited to share the works that will be presented by the group and our collaborating authors. You can find links to our ACL and ICML 2026 papers below!
Papers from CCG collaborations:
Decomposed Prompting Does Not Fix Knowledge Gaps, But Helps Models Say “I Don’t Know” (ACL Findings)

This paper examines how different prompting strategies influence the reliability of large language models (LLMs) in closed-book question answering, with a focus on their tendency to produce confident hallucinations. It compares model responses to direct questions with those generated using question decomposition: a multi-step reasoning plan for solving the original question. The results show that discrepancies between these two prompting approaches are highly indicative of hallucinations, offering a stronger signal than prior methods such as self-consistency.
Dhruv Madhwal and Lyuxin David Zhang and Dan Roth and Tomer Wolfson and Vivek Gupta, Decomposed Prompting Does Not Fix Knowledge Gaps, But Helps Models Say “I Don’t Know” ACL Findings (2026)
Sunday, July 5, 14:00-15:30 — Coronado
Toward Robust Evaluation for Multilingual Grammatical Error Correction: Can Large Language Models Replace Human References? (ACL)

Prior research has shown that using a <i>closest-gold reference</i> – i.e., a human reference generated with respect to the system output rather than the original text – yields more accurate performance estimates. This paper introduces <i>an automated method for generating closest-gold references</i> by prompting a large language model (LLM) with system outputs. We find that performance scores computed using automatic closest-gold references correlate well with human closest-golds, whereas standard reference-based evaluations show weak or no correlation. Building on this insight, we use both fixed human references and closest-gold references generated by Claude and Llama to compare the performance of supervised models and GPT-4 across 14 benchmarks spanning 12 languages.
Alla Rozovskaya and Dan Roth, Toward Robust Evaluation for Multilingual Grammatical Error Correction: Can Large Language Models Replace Human References? ACL (2026)
Monday, July 6, 09:00-10:30 — Grand Hall & Coronado, Poster Session D
MoNaCo: More Natural and Complex Questions for Reasoning Across Dozens of Documents (TACL, presented at ACL)

The landscape of AI-powered web search is being transformed: evolving from static large language models to LLM-powered “agents” which surface hard-to-find information through multiple rounds of reasoning and retrieval. Evaluating these agents requires measuring their ability to formulate and execute long-horizon plans that demand integrating information from dozens or even hundreds of web pages. Yet existing benchmarks are largely limited to tasks involving only a handful of sources, failing to capture the recall-intensive challenges found in many real-world applications.
This paper introduces MoNaCo, the first benchmark that evaluates AI agents’ ability to answer long-horizon questions that span dozens—and in some cases hundreds—of web pages. MoNaCo consists of 1,315 human-authored questions, each paired with ground-truth answers, supporting evidence, and gold-standard reasoning chains. We evaluate 15 frontier LLMs and identify substantial performance gaps: the top-performing model, o3, achieves a perfect score on just 38.7% of the benchmark.
Using MoNaCo, we show that deep reasoning across large document collections remains an open challenge for current AI agents, and discuss promising directions for bridging this gap.
Tomer Wolfson and Harsh Trivedi and Mor Geva and Yoav Goldberg and Dan Roth and Tushar Khot and Ashish Sabharwal and Reut Tsarfaty, MoNaCo: More Natural and Complex Questions for Reasoning Across Dozens of Documents TACL (2026)
Monday, July 6, 09:00-10:30 — Regatta, Oral Session D: Question Answering 1
REaR: Retrieve, Expand and Refine for Effective Multitable Retrieval (ACL)

This paper introduces REAR (Retrieve, Expand and Refine), a three-stage, LLM-free framework for efficient, high-fidelity multi-table retrieval. REAR (i) retrieves query-aligned tables, (ii) expands these with structurally joinable tables via fast, precomputed column-embedding comparisons, and (iii) refines them by pruning noisy or weakly related candidates.Despite being LLM-free, it delivers performance competitive with state-of-the-art LLM-augmented retrieval systems while achieving much lower latency and cost.
Rishita Agarwal and Himanshu Singhal and Peter Baile Chen and Manan Roy Choudhury and Dan Roth and Vivek Gupta, REaR: Retrieve, Expand and Refine for Effective Multitable Retrieval ACL (2026)
Tuesday, July7, 09:00-10:30 — Grand Hall
Is Code Better Than Language for Algorithmic Reasoning? (ICML)

This paper provides a methodology to compare two types of problem solving strategies with LLMs, 1) directly use CoT reasoning 2) call a tool (e.g. external runtime) by writing a piece of code. The methodology shows how tool calling is dominant through a theoretical perspective, and backs up the intuition with experimental results.
Terry Tong and Yu Feng and Surbhi Goel and Dan Roth, Is Code Better Than Language for Algorithmic Reasoning? ICML (2026)
A selection of further papers co-authored by Dan Roth
ToolScope: Enhancing LLM Agent Tool Use through Tool Merging and Context-Aware Filtering (ACL)

Large language model (LLM) agents rely on external tools to solve complex tasks, but real-world toolsets often contain noisy and overlapping tool options. This paper introduces ToolScope, which analyzes external toolsets to reduce redundancy and to select the most relevant tools for each query.
Marianne Menglin Liu and Daniel Garcia and Fjona Parllaku and Vikas Upadhyay and Syed Fahad Allam Shah and Dan Roth, ToolScope: Enhancing LLM Agent Tool Use through Tool Merging and Context-Aware Filtering ACL (2026)
SPENCE: A Syntactic Probe for Detecting Contamination in NL2SQL Benchmarks (ACL)

Large language models (LLMs) have achieved strong performance on natural language to SQL (NL2SQL) benchmarks, yet their reported accuracy may be inflated by contamination from benchmark queries or structurally similar patterns seen during training. We introduce SPENCE (Syntactic Probing and Evaluation of NL2SQL Contamination Effects), a controlled syntactic probing framework for detecting and quantifying such contamination.
Mohammadtaher Safarzadeh and Hitesh Laxmichand Patel and Afshin Orojlooyjadid and Graham Horwood and Dan Roth, SPENCE: A Syntactic Probe for Detecting Contamination in NL2SQL Benchmarks ACL (2026)
When Vision-Language Models Judge Without Seeing: Exposing Informativeness Bias (ACL)

This paper addresses a fundamental flaw in current VLM-as-a-Judge systems, namely informativeness bias, the tendency to blindly favor more informative answers while giving little attention to the image. To improve reliability, we propose BIRCH, which compares candidate answers against a self-generated anchor that corrects or verifies image details, shifting the judge’s focus back to image content and balancing informativeness with correctness.
Xiaohan Zou and Roshan Sridhar and Mohammadtaher Safarzadeh and Dan Roth, When Vision-Language Models Judge Without Seeing: Exposing Informativeness Bias ACL (2026)
JTPRO: A Joint Tool–Prompt Reflective Optimization Framework for Language Agents (ACL Findings)

Large language model (LLM) agents augmented with external tools often struggle as number of tools grow large and become domain-specific. This paper introduces Joint Tool-Prompt Reflective Optimization (JTPRO), a framework for improving tool-calling reliability in trace-supervised settings by iteratively using rollout-driven reflection to co-optimize global instructions and per-tool schema/argument descriptions for accurate tool selection and argument instantiation in large tool inventories.
Sandip Ghoshal and Anshul Mittal and Jyotika Singh and Miguel Ballesteros and Weiyi Sun and Fang Tu and Shailender Singh and Yassine Benajiba and Fahad Shah and Sujeeth Bharadwaj and Sujith Ravi and Dan Roth, JTPRO: A Joint Tool-Prompt Reflective Optimization Framework for Language Agents ACL Findings (2026)
MT-OSC: Path for LLMs that Get Lost in Multi-Turn Conversation (ACL Findings)

The routine approach of appending full chat history to prompts for multi-turn interactions rapidly exhausts LLM context windows, leading to diminishing returns as conversations extend. This paper introduces MT-OSC, a One-off Sequential Condensation framework that efficiently and automatically condenses chat history in the background without disrupting the user experience. The results establish MT-OSC as a scalable solution for multi-turn chats, enabling richer context within constrained input spaces, reducing latency and operational cost, while balancing performance.
Jyotika Singh and Fang Tu and Miguel Ballesteros and Weiyi Sun and Sandip Ghoshal and Michelle Yuan and Yassine Benajiba and Sujith Ravi and Dan Roth, MT-OSC: Path for LLMs that Get Lost in Multi-Turn Conversation ACL Findings (2026)
The Crowded Embedding Space: A Mean-Field Mechanism for Emergent Marginalization in Retrieval-Augmented Agents (ICML)

This paper introduces a formal framework to analyze how goal collisions in dense retrieval by RAG agents induce fundamental performance limits and emergent fairness issues inherent to spatial crowding. In our static analysis, we demonstrate that for a fixed embedding space, a phase transition occurs where minority user goals suffer a catastrophic collapse in performance as the density of majority goals increases. We then extend this to a dynamic model and derive a non-linear Fokker-Planck equation that governs the evolution of document embeddings as the agent updates them to maximize retrieval accuracy. The results provide a theoretical foundation for understanding a critical grounding failure mode in retrieval-augmented agents.
Shwan Ashrafi and Dan Roth, The Crowded Embedding Space: A Mean-Field Mechanism for Emergent Marginalization in Retrieval-Augmented Agents ICML (2026)






































