Efficiently understanding long-form videos remains a significant challenge in computer vision. In this work, we revisit temporal search paradigms for long-form video understanding and address a fundamental issue pertaining to all state-of-the-art (SOTA) long-context vision-language models (VLMs). Our contributions are twofold: First, we frame temporal search as a Long Video Haystack problem – finding a minimal set of relevant frames (e.g., one to five) from tens of thousands based on specific queries. Upon this formulation, we introduce LV-Haystack, the first dataset with 480 hours of videos, 15,092 human-annotated instances for both training and evaluation aiming to improve temporal search quality and efficiency. Results on LV-HAYSTACK highlight a significant research gap in temporal search capabilities, with current SOTA search methods only achieving 2.1% temporal F1score on the LongVideoBench subset.Next, inspired by visual search in images, we propose a lightweight temporal search framework, T* that reframes costly temporal search as spatial search. T* leverages powerful visual localization techniques commonly used in images and introduces an adaptive zooming-in mechanism that operates across both temporal and spatial dimensions. Extensive experiments show that integrating T* with existing methods significantly improves SOTA long-form video understanding. Under an inference budget of 32 frames, T* improves GPT-4o’s performance from 50.5% to 53.1% and LLaVAOneVision-OV-72B’s performance from 56.5% to 62.4% on the LongVideoBench XL subset. Our code, benchmark, and models are provided in the Supplementary material.

Large Language Models (LLMs) have shown growing potential in molecular sciences, but they often produce chemically inaccurate descriptions and struggle to recognize or justify potential errors.This raises important concerns about their robustness and reliability in scientific applications.To support more rigorous evaluation of LLMs in chemical reasoning, we present the MOLERR2FIX benchmark, designed to assess LLMs on error detection and correction in molecular descriptions.Unlike existing benchmarks focused on molecule-totext generation or property prediction, MOL-ERR2FIX emphasizes fine-grained chemical understanding.It tasks LLMs with identifying, localizing, explaining, and revising potential structural and semantic errors in molecular descriptions.Specifically, MOLERR2FIX consists of 1,193 fine-grained annotated error instances.Each instance contains quadruple annotations, i.e,.(error type, span location, the explanation, and the correction).These tasks are intended to reflect the types of reasoning and verification required in real-world chemical communication.Evaluations of current stateof-the-art LLMs reveal notable performance gaps, underscoring the need for more robust chemical reasoning capabilities.MolErr2Fix provides a focused benchmark for evaluating such capabilities and aims to support progress toward more reliable and chemically informed language models.All annotations and accompanying evaluation code are publicly available to facilitate future research.

Large Language Models (LLMs) have demonstrated improved generation performance by incorporating externally retrieved knowledge, a process known as retrieval-augmented generation (RAG). Despite the potential of this approach, existing studies evaluate RAG effectiveness by 1) assessing retrieval and generation components jointly, which obscures retrieval's distinct contribution, or 2) examining retrievers using traditional metrics such as NDCG, which creates a gap in understanding retrieval's true utility in the overall generation process. To address the above limitations, in this work, we introduce an automatic evaluation method that measures retrieval quality through the lens of information gain within the RAG framework. Specifically, we propose Semantic Perplexity (SePer), a metric that captures the LLM's internal belief about the correctness of the retrieved information. We quantify the utility of retrieval by the extent to which it reduces semantic perplexity post-retrieval. Extensive experiments demonstrate that SePer not only aligns closely with human preferences but also offers a more precise and efficient evaluation of retrieval utility across diverse RAG scenarios.

Understanding long video content is a complex endeavor that often relies on densely sampled frame captions or end-to-end feature selectors, yet these techniques commonly overlook the logical relationships between textual queries and visual elements. In practice, computational constraints necessitate coarse frame subsampling, a challenge analogous to “finding a needle in a haystack.” To address this issue, we introduce a semantics-driven search framework that reformulates keyframe selection under the paradigm of Visual Semantic-Logical Search (VSLS). Specifically, we systematically define four fundamental logical dependencies: 1) spatial co-occurrence, 2) temporal proximity, 3) attribute dependency, and 4) causal order. These relations dynamically update frame sampling distributions through an iterative refinement process, enabling context-aware identification of semantically critical frames tailored to specific query requirements. Our method establishes new state-of-the-art performance on the manually annotated benchmark in keyframe selection metrics. Furthermore, when applied to downstream video question-answering tasks, the proposed approach demonstrates the best performance gains over existing methods on LongVideoBench and Video-MME, validating its effectiveness in bridging the logical gap between textual queries and visual-temporal reasoning. The code will be publicly available.

Recently, large language models (LLMs) have been explored for integration with collaborative filtering (CF)-based recommendation systems, which are crucial for personalizing user experiences. However, a key challenge is that LLMs struggle to interpret the latent, non-semantic embeddings produced by CF approaches, limiting recommendation effectiveness and further applications. To address this, we propose FACE, a general interpretable framework that maps CF embeddings into pre-trained LLM tokens. Specifically, we introduce a disentangled projection module to decompose CF embeddings into concept-specific vectors, followed by a quantized autoencoder to convert continuous embeddings into LLM tokens (descriptors). Then, we design a contrastive alignment objective to ensure that the tokens align with corresponding textual signals. Hence, the model-agnostic FACE framework achieves semantic alignment without fine-tuning LLMs and enhances recommendation performance by leveraging their pre-trained capabilities. Empirical results on three real-world recommendation datasets demonstrate performance improvements in benchmark models, with interpretability studies confirming the interpretability of the descriptors. Code is available in \url{https://github.com/YixinRoll/FACE}.

Fully Homomorphic Encryption (FHE) is regarded as a promising way to protect data privacy with encrypted computation. Due to high computation overhead, hardware based FHE accelerators were proposed to speed up FHE applications. To support complicated FHE-encrypted neural network applications, multi-chiplet based FHE accelerators were further proposed for scaling up system size, whereas one of the challenges is designing efficient intra- and inter-chiplet interconnection networks to accelerate data transfer. Conventional regular topologies like mesh or Kite either lead to high inter-chiplet transmission latency or excessive power consumption as these topologies assume uniform bandwidth or radix for nodes/links, ignoring the highly irregular distribution of inter-chiplet communication volumes. On the other hand, the problem of generating customized intra- and inter-chiplet interconnection networks has high complexity and previous network-on-chip topology generation works cannot efficiently improve the performance of intra- and inter-chiplet interconnection networks. In this article, the intra- and inter-chiplet interconnection optimization problem is defined, aiming to minimize the execution time of FHE applications under cost and power constraints. To efficiently solve this problem, we propose a bilevel optimization algorithm, which decomposes the problem into three sub-problems: (1) FHE parameters selection, (2) task-to-core mapping, and (3) intra-/inter-chiplet interconnection network topology generation. These sub-problems are then solved iteratively. Experimental results demonstrate that our proposed method reduces execution time by 51.66%, 43.16%, 39.44%, 43.34%, and 27.70% compared with REED and four multi-chiplet based FHE accelerators with mesh, Kite, Butterfly, and Florets as inter-chiplet interconnection networks. Therefore, the proposed method can effectively accelerate FHE applications on large-scale multi-chiplet systems.

Gloss-free sign language translation (SLT) aims to develop well-performing SLT systems with no requirement for the costly gloss annotations, but currently still lags behind gloss-based approaches significantly. In this paper, we identify **a representation density problem** that could be a bottleneck in restricting the performance of gloss-free SLT. Specifically, the representation density problem describes that the visual representations of semantically distinct sign gestures tend to be closely packed together in feature space, which makes gloss-free methods struggle with distinguishing different sign gestures and suffer from a sharp performance drop. To address the representation density problem, we introduce a simple but effective contrastive learning strategy, namely SignCL, which encourages gloss-free models to learn more discriminative feature representation in a self-supervised manner. Our experiments demonstrate that the proposed SignCL can significantly reduce the representation density and improve performance across various translation frameworks. Specifically, SignCLachieves a significant improvement in BLEU score for the Sign Language Transformer and GFSLT-VLP on the CSL-Daily dataset by 39\% and 46\%, respectively, without any increase of model parameters. Compared to Sign2GPT, a state-of-the-art method based on large-scale pre-trained vision and language models, SignCLachieves better performance with only 35\% of its parameters. We will release our code and model to facilitate further research.

Sign language gloss translation aims to translate the sign glosses into spoken language texts, which is challenging due to the scarcity of labeled gloss-text parallel data.Back-translation (BT), which generates pseudo parallel data by translating in-domain spoken language texts into sign glosses, has been applied to alleviate the data scarcity problem.However, the lack of large-scale high-quality in-domain spoken language text data limits the effect of BT.In this paper, to overcome the limitation, we propose a Prompt based domain text Generation (PGEN) approach to produce the large-scale in-domain spoken language text data.Specifically, PGEN randomly concatenates sentences from the original in-domain spoken language text data as prompts to induce a pre-trained language model (i.e., GPT-2) to generate spoken language texts in similar style.Experimental results on three benchmarks of sign language gloss translation in varied languages demonstrate that BT with spoken language texts generated by PGEN significantly outperforms the compared methods.In addition, as the scale of spoken language texts generated by PGEN increases, the BT technique can achieve further improvements, demonstrating the effectiveness of our approach.We release the code and data for facilitating future research in this field 1 .