Papers by Zhicheng Liu

45 papers
How Does Context Matter? On the Robustness of Event Detection with Context-Selective Mask Generalization (2020.findings-emnlp)

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Challenge: Existing studies focus on improving the overall performance of an ED model, but few consider the robustness of an existing model.
Approach: They propose a new training mechanism that can effectively mine context-specific patterns for learning and robustify an ED model.
Outcome: The proposed model can learn a complementary predictive bias with most ED models that use full context for feature learning.
Less is More: Pretrain a Strong Siamese Encoder for Dense Text Retrieval Using a Weak Decoder (2021.emnlp-main)

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Challenge: Dense retrieval requires high-quality text sequence embeddings to support effective search in the representation space.
Approach: They propose a self-learning method that pre-trains the autoencoder using a weak decoder to push the encoder to provide better sequence representations.
Outcome: The proposed model significantly boosts the effectiveness and few-shot ability of dense retrieval models on web search, news recommendation, and open domain question answering.
Empowering Math Problem Generation and Reasoning for Large Language Model via Synthetic Data based Continual Learning Framework (2025.emnlp-main)

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Challenge: Existing learning frameworks for large language models (LLMs) for math problem generation are limited and lack quality data.
Approach: They propose a synthetic data based continual learning framework to improve LLMs ability for MPG and math reasoning.
Outcome: The proposed framework improves performance on large language models and math reasoning using supervised fine-tuning, data synthesis and direct preference optimization.
CoRanking: Collaborative Ranking with Small and Large Ranking Agents (2025.findings-emnlp)

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Challenge: Listwise ranking based on Large Language Models (LLMs) has achieved state-of-the-art performance in Information Retrieval (IR) however, their effectiveness often depends on LLMs with massive parameter scales and computationally expensive sliding window processing, leading to substantial efficiency bottlenecks.
Approach: They propose a Collaborative Ranking framework (CoRanking) for LLM-based listwise ranking based on large language models with massive parameter scales and computationally expensive sliding window processing.
Outcome: The proposed framework reduces ranking latency by approximately 70% while improving effectiveness compared to the standalone large reranker.
ProcVQA: Benchmarking the Effects of Structural Properties in Mined Process Visualizations on Vision–Language Model Performance (2025.findings-emnlp)

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Challenge: Vision-Language Models have shown impressive capabilities and notable failures in data visualization understanding tasks.
Approach: They propose a benchmark to analyze how specific properties within a visualization type affect VLM performance.
Outcome: The proposed benchmark examines how specific properties affect VLM performance . it shows that models exhibit steep drops on multi-hop reasoning and extraction errors increase with edge density .
RAG-Studio: Towards In-Domain Adaptation of Retrieval Augmented Generation Through Self-Alignment (2024.findings-emnlp)

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Challenge: Existing RAG systems that use pre-trained LLMs and retrievers often fail in specialized domains and applications.
Approach: They propose a self-aligned training framework that adapts general RAG models to specific domains solely through synthetic data.
Outcome: Experiments on specialized domain corpus, general LLM, and general retriever show that the self-aligned training framework outperforms human-annotated training data in specialized fields.
Rehearsal-free Continual Language Learning via Efficient Parameter Isolation (2023.acl-long)

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Challenge: Existing methods for learning continual tasks do not cache history data, which makes the problem more challenging.
Approach: They propose a method that allocates a small portion of private parameters and learns them with a shared pre-trained model.
Outcome: The proposed method is comparable to existing methods and comparable to those using historical data.
Flaming-hot Initiation with Regular Execution Sampling for Large Language Models (2025.findings-naacl)

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Challenge: Large language models (LLMs) have demonstrated remarkable capabilities across various domains since the release of ChatGPT . a key challenge in developing these general capabilities is efficiently sourcing diverse, high-quality data.
Approach: They introduce Flaming-hot Initiation with Regular Execution (FIRE) sampling to efficiently find good responses by promoting diversity.
Outcome: The proposed method enhances inference-time generation quality and benefits training in the alignment stage.
A Multi-Task Embedder For Retrieval Augmented LLMs (2024.acl-long)

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Challenge: Existing retrieval methods face limitations in terms of knowledge, memory, and action.
Approach: They propose a retrieval enhancement mechanism that brings in useful information from external sources to augment the LLM.
Outcome: The proposed method significantly improves the LLM’s performance in various downstream tasks while introducing superior retrieval augmentation’s effect over both general and task-specifc retrievers.
AgentV-RL: Scaling Reward Modeling with Agentic Verifier (2026.findings-acl)

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Challenge: Existing approaches to improve LLM reasoning are limited in complex domains and lack external grounding makes verifiers unreliable on computation-intensive tasks.
Approach: They propose a framework that transforms reward modeling into a multi-turn, tool-augmented deliberative process.
Outcome: The proposed framework surpasses state-of-the-art ORMs by 25.2% under parallel and sequential TTS.
INTERS: Unlocking the Power of Large Language Models in Search with Instruction Tuning (2024.acl-long)

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Challenge: Large language models (LLMs) have demonstrated impressive capabilities in various natural language processing tasks, but their application to information retrieval tasks is still challenging due to the infrequent occurrence of many IR-specific concepts in natural language.
Approach: They propose to use instruction tuning to enhance LLMs' proficiency in IR tasks by combining a dataset with manually written templates to analyze the effects of instruction design, template diversity, few-shot demonstrations, and the volume of instructions.
Outcome: The proposed model can be used to perform query understanding, document understanding, and query-document relationship understanding tasks.
Two Streams, One Sarcasm: Orthogonal Expert Tuning for Holistic Multimodal Sarcasm Understanding (2026.acl-long)

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Challenge: Existing benchmarks for multimodal satirical cognition hinder evaluation of multimodal Sarcasm Understanding . lack of a unified benchmark for holistic satire cognition hampers evaluation of MSU .
Approach: They propose a framework to decouple experts into orthogonal shared perception and private execution streams to physically block gradient interference between tasks.
Outcome: The proposed framework achieves superior performance on DocMSU-PLUS.
Scene Restoring for Narrative Machine Reading Comprehension (2020.emnlp-main)

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Challenge: Narrative passages describe a chain of events, which helps the machine understand the passage comprehensively.
Approach: They propose a method to let machine read narrative passages with their prior knowledge . they build a scene graph using Atomic as external knowledge and encode it with GDIN .
Outcome: The proposed method achieves state-of-the-art on a Story Cloze Test and CosmosQA datasets.
ReasonRank: Empowering Passage Ranking with Strong Reasoning Ability (2026.acl-long)

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Challenge: Existing rerankers perform poorly in complex ranking scenarios due to the scarcity of reasoning-intensive training data.
Approach: They propose an automated reasoning-intensive training framework which generates high-quality training labels from training queries and passages.
Outcome: The proposed model outperforms baselines significantly and achieves much lower latency than the pointwise reranker.
ChatRetriever: Adapting Large Language Models for Generalized and Robust Conversational Dense Retrieval (2024.emnlp-main)

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Challenge: a conversational search system requires accurate interpretation of user intent from complex multi-turn contexts.
Approach: They propose a dual-learning approach that adapts LLMs for retrieval via contrastive learning while enhancing the complex session understanding through masked instruction tuning.
Outcome: The proposed approach outperforms existing retrieval methods on five conversational search benchmarks.
Mixture of Heterogeneous Grouped Experts for Language Modeling (2026.acl-industry)

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Challenge: Large Language Models (LLMs) based on Mixture-of-Experts (MoE) enforce uniform expert sizes, creating a rigidity that fails to align computational costs with varying token-level complexity.
Approach: They propose a mixture of heterogeneous grouped experts (MoHGE) that allows for flexible, resource-aware expert combinations.
Outcome: The proposed model matches the performance of existing Mixture-of-Experts architectures while maintaining balanced GPU utilization.
Read As Human: Compressing Context via Parallelizable Close Reading and Skimming (2026.acl-long)

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Challenge: Existing task-aware methods require loading the entire input sequence at once for compression, which suffer from computational inefficiency.
Approach: They propose a framework that adopts an adaptive hybrid reading strategy to reduce computational inefficiency and redundant information in long-context scenarios.
Outcome: Experiments show that RAM outperforms baselines on multiple question answering and summarization benchmarks while delivering up to a 12x speedup on long inputs.
Aligning Paralinguistic Understanding and Generation in Speech LLMs via Multi-Task Reinforcement Learning (2026.eacl-industry)

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Challenge: Using paralinguistic cues is challenging for speech large language models, authors say . limited training data, annotation difficulty, and models exploiting lexical shortcuts are challenges . a recent study shows that modeling paralinguistic reasoning with multitask RL improves paralinguistics understanding .
Approach: They propose multi-task reinforcement learning with chain-of-thought prompting that elicits explicit affective reasoning.
Outcome: The proposed model improves paralinguistics understanding over baselines and strong proprietary models by 8-12% on Expresso, IEMOCAP, and RAVDESS.
Agentic-R: Learning to Retrieve for Agentic Search (2026.findings-acl)

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Challenge: Existing retrievers for single-turn retrieval-augmented generation (RAG) rely on similarity-based retrievers, but similar passages are not always useful for final answer generation.
Approach: They propose a retrieval-augmented-generation retriever that integrates reasoning with retrieval . they use local query-passage relevance and global answer correctness to measure passage utility .
Outcome: The proposed retriever outperforms existing retrievers on QA benchmarks on seven single-hop and multi-hop searches.
FineRAG: Fine-grained Retrieval-Augmented Text-to-Image Generation (2025.coling-main)

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Challenge: Recent advances in text-to-image generation still exhibit limitations in terms of knowledge access.
Approach: They propose a fine-grained retrieval-augmented image generation model that breaks down the retrieval task into four critical stages: query decomposition, candidate selection, retrieval augmented diffusion, and self-reflection.
Outcome: The proposed method significantly reduces noise associated with retrieval-augmented image generation and performs better in complex, open-world scenarios.
Prompt-Guided Retrieval Augmentation for Non-Knowledge-Intensive Tasks (2023.findings-acl)

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Challenge: Recent studies focus on retrieval to solve knowledge-intensive tasks, but the potential of retrieval for non-knowledge-intensive (NKI) tasks remains under-explored.
Approach: They propose a task-agnostic retrieval framework for NKI tasks that uses a static index and a prompt-guided reranker to re-rank the nearest evidence according to task-specific relevance.
Outcome: The proposed framework outperforms state-of-the-art retrieval-augmented methods on NKI tasks and will be released for further research.
StableToolBench-MirrorAPI: Modeling Tool Environments as Mirrors of 7,000+ Real-World APIs (2025.findings-acl)

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Challenge: Existing tool environments face challenges in balancing stability, scale, and realism, especially for benchmarking purposes.
Approach: They propose a framework that trains specialized LLMs to accurately simulate real API responses by supervised fine-tuning and chain-of-thought reasoning.
Outcome: The proposed framework achieves superior accuracy and stability compared to state-of-the-art methods on the newly constructed MirrorAPI-Bench and its integration into StableToolBench.
CodexGraph: Bridging Large Language Models and Code Repositories via Code Graph Databases (2025.naacl-long)

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Challenge: Large Language Models excel in stand-alone code tasks but struggle with handling entire code repositories.
Approach: They propose a system that integrates LLM agents with graph database interfaces extracted from code repositories.
Outcome: The proposed system integrates LLM agents with graph database interfaces extracted from code repositories.
Grounding Language Model with Chunking-Free In-Context Retrieval (2024.acl-long)

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Challenge: CFIC retrieval approach eliminates the need for document chunking and provides a more efficient and efficient method for RAG systems.
Approach: They propose a Chunking-Free In-Context retrieval approach specifically tailored for RAG systems . they employ auto-aggressive decoding to accurately identify specific evidence text .
Outcome: The proposed method is better than traditional methods on open question answering datasets.
Sliding Windows Are Not the End: Exploring Full Ranking with Long-Context Large Language Models (2025.acl-long)

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Challenge: Existing methods for listwise passage ranking use sliding window approach, which is inefficient as it requires repetitive and serialized processing.
Approach: They propose a listwise label construction approach and importance-aware learning objective for full ranking.
Outcome: The proposed method outperforms existing methods in listwise ranking tasks.
ATG: Benchmarking Automated Theorem Generation for Generative Language Models (2024.findings-naacl)

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Challenge: Existing generative language models (LMs) can generate new or reusable theorems, but their ability to generate new theorels is under-explored.
Approach: They propose to use Metamath library to generate new theorems that can be saved as reusable knowledge for future theoretical proving.
Outcome: The proposed benchmark evaluates whether an agent can generate valuable (and possibly brand new) theorems that are applicable for downstream theoretic proving as reusable knowledge.
How Credible Is an Answer From Retrieval-Augmented LLMs? Investigation and Evaluation With Multi-Hop QA (2025.coling-main)

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Challenge: Retrieval-augmented large language models (RaLLMs) are reshaping knowledge acquisition, offering long-form, knowledge-grounded answers through advanced reasoning and generation capabilities.
Approach: They propose a benchmarking system to evaluate RaLLMs' correctness and Groundedness to determine their reliability in multi-hop question-answering tasks.
Outcome: The proposed model-based evaluation pipeline for multi-hop question-answering tasks reveals that the model generates inaccuracies when dealing with flawed or partial knowledge.
P3: Prompts Promote Prompting (2025.findings-acl)

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Challenge: Recent advances in prompt optimization have shown effectiveness of using multiple components to optimize models . however, such unilateral approaches often yield suboptimal results due to interdependent nature of these components.
Approach: They propose a self-improvement framework that optimizes both system and user prompts . they use offline optimized prompts to promote online prompt optimization .
Outcome: The proposed framework improves performance on general and reasoning tasks.
Single LLM, Multiple Roles: A Unified Retrieval-Augmented Generation Framework Using Role-Specific Token Optimization (2025.emnlp-main)

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Challenge: Existing studies have optimized retrieval-augmented generation (RAG) across sub-tasks, but integrating these optimizations into a unified framework remains challenging.
Approach: They propose a unified retrieval-augmented generation framework that optimizes role-specific tokens for multi-task processing.
Outcome: The proposed framework achieves efficient multi-task processing through role-specific token optimization.
Coarse-to-Fine: Hierarchical Multi-task Learning for Natural Language Understanding (2022.coling-1)

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Challenge: Existing methods to learn downstream tasks by stitches skill block lack rationality and interpretation.
Approach: They propose a hierarchical framework with a coarse-to-fine paradigm for generalized text representations from the large-scale corpus.
Outcome: The proposed model learns basic language properties from all tasks and boosts performance on relevant tasks.
StableToolBench: Towards Stable Large-Scale Benchmarking on Tool Learning of Large Language Models (2024.findings-acl)

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Challenge: Large Language Models (LLMs) have witnessed remarkable advancements in recent years, prompting the exploration of tool learning.
Approach: They propose a virtual API server and stable evaluation system to assess the stability of large-scale real-time APIs.
Outcome: The proposed benchmarks demonstrate the stability of the proposed system and its caching system.
HealMe: Harnessing Cognitive Reframing in Large Language Models for Psychotherapy (2024.acl-long)

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Challenge: Large Language Models (LLMs) can be used in psychotherapy to overcome challenges such as shame, distrust, and resource scarcity.
Approach: They propose a cognitive reframing therapy method that uses empathetic dialogue to address deep-rooted negative thoughts and fosters rational, balanced perspectives.
Outcome: The proposed model outperforms other models in terms of empathy, guidance, and logical coherence, demonstrating its effectiveness and potential positive impact on psychotherapy.
Boosting Long-Context Information Seeking via Query-Guided Activation Refilling (2025.acl-long)

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Challenge: Existing methods for processing long contexts are ineffective due to their inherent context window limitations and the computational burden of extensive key-value activations.
Approach: They propose a method for processing long context information-seeking tasks via query-guided ACtivation REfilling (ACRE) a bi-layer KV Cache is constructed where the layer-1 cache compactly captures global information and the layer-2 cache provides detailed, localized information.
Outcome: The proposed method achieves significant improvements in both performance and efficiency on a variety of long-context information-seeking datasets.
Generalizing Conversational Dense Retrieval via LLM-Cognition Data Augmentation (2024.acl-long)

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Challenge: Existing conversational dense retrieval models view a conversation as a fixed sequence of questions and responses, and these alternate conversations are unrecorded.
Approach: They propose a framework for generalizing Conversational dense retrieval via LLM-cognition data Augmentation (ConvAug) they first generate multi-level augmented conversations to capture the diverse nature of conversational contexts.
Outcome: The proposed framework generalizes Conversational dense retrieval via LLM-cognition data Augmentation on four public datasets.
Multi-Scale Progressive Attention Network for Video Question Answering (2021.acl-short)

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Challenge: Experimental evaluations on three benchmarks: TGIF-QA, MSVD-QA and MSRVTT-QA show our method has achieved state-of-the-art performance.
Approach: They propose a multi-scale progressive attention network to fuse visual and text information.
Outcome: The proposed method achieves state-of-the-art on three benchmarks: TGIF-QA, MSVD-QA and MSRVTT-QA.
Hybrid Inverted Index Is a Robust Accelerator for Dense Retrieval (2023.emnlp-main)

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Challenge: Inverted file structure is a common technique for accelerating dense retrieval, but its lossy nature degrades it.
Approach: They propose a hybrid index where embedding clusters and salient terms work collaboratively to accelerate dense retrieval.
Outcome: The proposed method achieves lossless retrieval quality with competitive efficiency across index settings.
Search-Oriented Conversational Query Editing (2023.findings-acl)

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Challenge: Existing CQR models are not learned toward improving the downstream search performance . existing models generate the rewrite token-by-token from scratch .
Approach: They propose a text editing-based CQR model tailored for conversational search . they propose rewrite tokens are selected from the dialogue in a non-autoregressive fashion .
Outcome: The proposed model outperforms state-of-the-art models on three conversational search benchmarks while having low rewriting latency.
Memory Matters More: Event-Centric Memory as a Logic Map for Agent Searching and Reasoning (2026.findings-acl)

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Challenge: Existing methods for storing and retrieving memory are limited by shallow semantic retrieval.
Approach: They propose a memory mechanism that organizes and retrieves past experiences to support decision-making.
Outcome: Experiments on LoCoMo and NarrativeQA show that CompassMem improves retrieval and reasoning performance across multiple backbone models.
Chinese SimpleQA: A Chinese Factuality Evaluation for Large Language Models (2025.acl-long)

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Challenge: Current frontier models sometimes generate false outputs or answers that are not substantiated by evidence.
Approach: They propose Chinese SimpleQA, a Chinese benchmark to evaluate LLMs' factuality . they focus on Chinese language over 6 major topics with 99 diverse subtopics .
Outcome: The Chinese SimpleQA benchmark evaluates the factuality ability of LLMs . the questions and answers are short and easy-to-evaluate .
LLMs + Persona-Plug = Personalized LLMs (2025.acl-long)

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Challenge: Large language models (LLMs) have demonstrated extraordinary capabilities in natural language understanding, generation, and reasoning.
Approach: They propose a plug-and-play LLM model that embeds a user-specific embedding for each individual by modeling her historical contexts through a lightweight plug-in user embedder module.
Outcome: Experiments on various tasks in the language model personalization (LaMP) benchmark show that the proposed model significantly outperforms existing personalized LLM approaches.
SRAP-Agent: Simulating and Optimizing Scarce Resource Allocation Policy with LLM-based Agent (2024.findings-emnlp)

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Challenge: Existing research on the allocation of public scarce resources has limitations due to data scarcity and data scariness.
Approach: They propose a framework that integrates Large Language Models into economic simulations . they conduct extensive policy simulation experiments to verify the framework's effectiveness .
Outcome: The proposed framework bridges the gap between theoretical models and real-world dynamics by integrating large language models into economic simulations.
MoCa: Modality-aware Continual Pre-training Makes Better Bidirectional Multimodal Embeddings (2026.acl-long)

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Challenge: Existing approaches to embed multimodal models face limitations such as suboptimal causal attention in VLMs and limited diversity in training objectives and data.
Approach: They propose a framework for transforming pre-trained VLMs into bidirectional multimodal embedding models.
Outcome: The proposed model improves performance across MMEB and ViDoRe-v2 benchmarks and exhibits strong scalability with both model size and training data on MMEF.
Improving Speech Translation by Fusing Speech and Text (2023.findings-emnlp)

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Challenge: In speech translation, multimodal data to address limitations of individual modalities has shown significant effectiveness.
Approach: They propose a cross-modal model which supports three input modalities for speech, text and fused speech-text.
Outcome: The proposed model achieves an average of 34.0 BLEU on MuST-C, GigaST and newstest benchmark.
Can Large Language Models Detect Errors in Long Chain-of-Thought Reasoning? (2025.acl-long)

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Challenge: Recent advances in o1-like models have generated long Chain-of-Thought reasoning steps to improve the reasoning abilities of existing Large Language Models (LLMs).
Approach: They propose a DeltaBench to analyze the quality and effectiveness of o1-like models and measure their ability to detect errors in long COT reasoning.
Outcome: The proposed model can detect errors in long COT reasoning.
PaperScope: A Multi-Modal Multi-Document Benchmark for Agentic Deep Research Across Massive Scientific Papers (2026.findings-acl)

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Challenge: Existing benchmarks focus on single-document understanding, whereas real scientific workflows require integrating evidence from multiple papers.
Approach: They propose a multi-modal multi-document benchmark for agentic deep research that integrates evidence from multiple documents.
Outcome: Experimental results show that even advanced systems achieve limited scores on PaperScope . paper provides a rigorous benchmark alongside a pipeline for constructing large multi-modal, multi-source deep research datasets.

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