Existing long-form factuality evaluation relies on the decompose-retrieve-verify pipeline. However, the pipeline suffers from noise from claim decomposition and fixed verification granularity, resulting in unreliable results. We propose ElementCheck, a complexity-aware framework that verifies long-form outputs via sentence elements. Instead of uniformly decomposing sentences into atomic sub-claims, ElementCheck extracts entity pairs that are explicitly linked through verifiable connections in the original sentence as elements, and organizes these into an element graph. The graph topology provides a structural signal for estimating sentence complexity, enabling direct verification for simple sentences and targeted element-level refinement and verification for complex ones. To support fine-grained evaluation, we construct a new benchmark FastFact-Sent by mapping isolated claims from FastFact-Bench back to their source sentences. Experiments on FastFact-Sent and two domain-specific benchmarks show ElementCheck consistently improves factuality verification across five backbone models while maintaining a favorable accuracy-cost trade-off. Further analyses demonstrate that complexity-aware verification reduces unnecessary re-verification and maintains stability across different backbones. The code is available at Here.

Video misinformation increasingly operates at the semantic and evidential level: authentic footage may be selectively edited, temporally reordered, spliced across sources, or augmented with AI-generated content to construct false narratives. Such evidence-dependent manipulations cannot be reliably verified from the input video alone, because the missing, reordered, replaced, or recontextualized evidence lies outside the video itself. We introduce EVID-Bench, a benchmark for search-grounded video misinformation detection, where a system must search the open web for related videos and identify what information is false through cross-video comparison. EVID-Bench comprises 222 videos spanning 9 manipulation types across 3 categories: AI generation, single-source editing, and multi-source editing. All samples are verified to be undetectable by frontier models through visual inspection alone. We evaluate nine frontier multimodal models using a retrieval-augmented verification baseline. The best system achieves only 61.43% point-level accuracy and 43.24% video-level accuracy, with AI-generated manipulations remaining especially difficult. Error analysis reveals recurring challenges: models fixate on irrelevant anchors, misattribute synthetic content to editorial splicing, and terminate search prematurely before fully explaining the manipulation.

In recent years, large language models (LLMs) have made rapid progress in information retrieval, yet existing research has mainly focused on text or static multimodal settings. Open-domain video shot retrieval, which involves richer temporal structure and more complex semantics, still lacks systematic benchmarks and analysis. To fill this gap, we introduce ShotFinder, a benchmark that formalizes editing requirements as keyframe-oriented shot descriptions and introduces five types of controllable single-factor constraints: Temporal order, Color, Visual style, Audio, and Resolution. We curate 1,210 high-quality samples from YouTube across 20 thematic categories, using large models for generation with human verification. Based on the benchmark, we propose ShotFinder, a text-driven three-stage retrieval and localization pipeline: (1) query expansion via video imagination, (2) candidate video retrieval with a search engine, and (3) description-guided shot localization. Experiments on multiple closed-source and open-source models reveal a significant gap to human performance, with clear imbalance across constraints: temporal localization is relatively tractable, while color and visual style remain major challenges. These results reveal that open-domain video shot retrieval is still a critical capability that multimodal large models have yet to overcome.

Large language models (LLMs) can propose vaccine adjuvant designs with plausible mechanistic rationales, but such outputs often lack grounding in established immunological knowledge. We present SAVANT, a neuro-symbolic framework for LLM-based adjuvant design that combines two-stage constrained generation with literature-grounded verification. SAVANT first generates a natural-language design rationale, then renders it into an ontology-constrained domain-specific language (DSL) using logic masks and finite-state control. To reason under fragmented evidence and incomplete first-principles rules, SAVANT verifies generated designs against literature-derived symbolic evidence through minimal sub-theorem proof. In expert-aligned evaluation, SAVANT shows greater stability in stage-level rank alignment than the strongest LLM-judge baselines, while achieving the strongest alignment for immune-effect support and mechanistic reasoning. SAVANT provides graded, interpretable assessments that distinguish supported mechanisms, under-supported hypotheses, and knowledge gaps for hypothesis-driven experimentation. Data and code will be released at https://github.com/banjiuyufen/SAVANT.

Vision-Language-Action (VLA) models are built on the premise that pre-trained Vision-Language Models (VLMs) can supply general semantic understanding ability for embodied tasks. However, we find that robotic fine-tuning can severely erode this capability: VQA benchmarks and layer-wise CKA analysis reveal rapid representational drift, and co-training with general vision-language data does not prevent the collapse. We propose TwinBrainVLA, an asymmetric dual-stream VLA that keeps a pre-trained "Left Brain" strictly frozen as a semantic generalist while training a "Right Brain" as an embodied control specialist. Its Asymmetric Mixture-of-Transformers (AsyMoT) mechanism lets the Right Brain query frozen Left-Brain key-value representations at every transformer layer, integrating intact semantic knowledge without corrupting it. Across SimplerEnv, RoboCasa, LIBERO, and real-robot experiments, TwinBrainVLA outperforms strong baselines and large-scale embodied models, achieving a 14.3% improvement on SimplerEnv and a 2.7× gain in physical-robot instruction generalization.

Test-time scaling (TTS) has emerged as a powerful paradigm for enhancing large language model (LLM) reasoning by allocating additional compute during inference. External TTS, particularly Best-of- selection, generates multiple reasoning trajectories and selects the optimal candidate. However, existing process reward models (PRMs) for Best-of-N selection face a critical limitation: they were not originally designed for this task and instead rely on human-designed evaluation criteria (e.g., readability, coherence, formatting) that often misalign with actual answer correctness, leading to unstable and oscillatory performance as N increases. We introduce TrajSelector a framework specifically designed for robust and effective Best-of-N selection. Our key insight is to leverage the sampler LLM’s intrinsic hidden states as self-reflective signals, which naturally align with correctness rather than human-imposed stylistic preferences. A lightweight verifier (0.6B–4B parameters) scores reasoning steps using these hidden states, trained via outcome supervision to eliminate reliance on step-level human annotations. Experiments across six mathematical reasoning benchmarks demonstrate that TrajSelector achieves robust monotonic improvements: in Best-of-32 settings, even our smallest 0.6B verifier outperforms majority voting by 4.61% and existing 7B PRMs by 4.31–12.21%, while our 4B verifier reaches 64.05% accuracy with stable scaling behavior as N increases from 1 to 64.

Recent OCR models achieve strong results on document benchmarks, with several 1–2B OCR-specialized models surpassing much larger general multimodal LLMs (MLLMs). However, complex real-world documents often contain blur, cropping, curved text, handwriting, and unfamiliar structures, which remain challenging for current OCR systems. We trace this gap to a shift in the error source: errors on canonical benchmarks mainly arise from layout analysis, including localization, element classification, and reading order, while errors under these challenging conditions mainly arise from content recognition. To this end, we propose CL-OCR, a two-stage framework that first fuses semantic structure from an MLLM-based detector with geometric candidates from a vision detector to obtain calibrated layouts, then enhances recognition via a shared LoRA adapter gated by a lightweight router. We further construct OCRWildBench and a companion training split to study these conditions. Experiments show that CL-OCR remains competitive on canonical benchmarks and achieves the strongest overall performance among OCR-specialized models on OCRWildBench.

Multi-modal Retrieval-Augmented Generation (RAG) has emerged as a highly effective paradigm for Knowledge-Based Visual Question Answering (KB-VQA). Despite recent advancements, prevailing methods still primarily depend on images as the retrieval key, and often overlook or misplace the role of Vision-Language Models (VLMs), thereby failing to leverage their potential fully. In this paper, we introduce WikiSeeker, a novel multi-modal RAG framework that bridges these gaps by implementing a multi-modal retriever and redefining the role of VLMs. Rather than serving merely as answer generators, we assign VLMs two specialized agents: a Refiner and an Inspector. The Refiner utilizes the capability of VLMs to rewrite the textual query according to the input image, significantly improving the performance of the multimodal retriever. The Inspector facilitates a decoupled generation strategy by selectively routing reliable retrieved context to another LLM for answer generation, while relying on the VLM’s internal knowledge when retrieval is unreliable. Extensive experiments on EVQA, InfoSeek, and M2KR demonstrate that WikiSeeker achieves state-of-the-art performance, with substantial improvements in both retrieval accuracy and answer quality.

Large reasoning models (LRMs) show strong capabilities in complex reasoning, yet their marginal gains on evidence-dependent factual questions are limited. We find this limitation is partially attributable to a reasoning–answer hit gap, where the model identifies the correct facts during reasoning but fails to incorporate them into the final response, thereby reducing factual fidelity. To address this issue, we propose MR-ALIGN, a Meta-Reasoning informed alignment framework that enhances factuality without relying on external verifiers. MR-ALIGN quantifies state-transition probabilities along the model’s thinking process and constructs a transition-aware implicit reward that reinforces beneficial reasoning patterns while suppressing defective ones at the atomic thinking segments. This re-weighting reshapes token-level signals into probability-aware segment scores, encouraging coherent reasoning trajectories that are more conducive to factual correctness. Empirical evaluations across four factual QA datasets and one long-form factuality benchmark show that MR-ALIGN consistently improves accuracy and truthfulness while reducing misleading reasoning. These results highlight that aligning the reasoning process itself, rather than merely the outputs, is pivotal for advancing factuality in LRMs.