Research

New AI papers from arXiv, picked daily and explained with their claims, benchmark results and code.

2566 articles · page 29 of 54 · The Research front page

Theory

Flow matching avoids the curse of dimensionality by adapting to intrinsic data dimension

Chakraborty et al. derive finite-sample generalization bounds for flow-matching generative models. They show that the Wasserstein-p distance between the learned and true distribution scales as n^{-1/d} where d is the intrinsic dimension of the data, not the much larger ambient dimension. This result explains why flow matching succeeds on high-dimensional data that lie on low-dimensional manifolds.

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Safety & security

Post-training reduces AI models' steerability toward opposing viewpoints

Controlled fine-tuning experiments show that standard post-training methods—SFT, RLHF, and DPO—do not merely shift a model's default behavior toward a trained perspective, but also degrade its ability to faithfully adopt an opposing perspective when instructed in-context. This reveals an inherent tension between optimizing for a single set of values and preserving the technical capacity needed to serve diverse stakeholders.

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Speech & audio

Adapting a speech language model with self-generated prefix supervision improves simultaneous translation quality-latency trade-offs.

The authors adapted a full-utterance speech language model to simultaneous translation by creating target prefixes from its own translations of partial waveforms. Using a confidence threshold to control latency, they found that multi-turn append-only decoding reduces commit-calibration error by 63–68% overall and 68–80% at early prefixes, while single-turn forced-prefix training yields only modest gains. The synthesis margin that controls supervision density introduces a non-monotonic trade-off, with a small margin sometimes extending low-latency coverage on shorter utterances but a larger margin degrading quality.

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Generative media

SatisDive method navigates the satisfaction-diversity frontier for text-to-image generation

The authors formulate text-to-image batch generation as satisficing: each image must meet a reward floor and the batch must meet a diversity cutoff. Varying the reward floor traces a Pareto frontier between worst-image reward and batch diversity. SatisDive, a training-free method, traverses this frontier and improves worst-candidate reward over FK steering by up to 0.43 and 0.70 on FLUX and SANA at matched DreamSim diversity.

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Reinforcement learning

Lexicographic distillation preserves priority-ordered capabilities in multi-objective RL

The authors propose LMOPD, a multi-teacher distillation method that uses a lexicographic priority order to route each student rollout to the specialist for the highest-priority unmet objective. The chosen specialist's token-level correction is then projected against higher-priority experts to avoid harmful interference. On math benchmarks with 30B models, LMOPD retained over 90% of top-priority gains in a four-expert setting, outperforming baselines.

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Language models

Personalized LLMs can share most adaptation capacity across users, needing only tiny per-user code.

The authors revisit personalized adaptation for large language models by asking how much of a personalized adapter is actually personal. Through empirical analyses, they find that independent user adapters contain substantial reusable structure and that user history provides transferable correction signals. They propose LINEUP, which learns a bank of reusable low-rank personalization factors, composes them via user-conditioned recall and query-dependent calibration, and restricts target-user adaptation to a tiny eight-scalar code. Across six LaMP tasks spanning classification, prediction, and generation, LINEUP achieves the best mean performance on all 12 reported metrics, demonstrating that rich personalization can be supported primarily by shared capacity.

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Robotics & embodied AI

Offline stitching of robot demos boosts policy success by 21 percentage points

The authors present NEEDLE, an offline dataset-augmentation algorithm that stitches together useful segments from multiple robot demonstrations by adding short, verified action bridges. Using only RGB images and proprioception, NEEDLE identifies connections that bypass detours, combine complementary behaviors, and recover from failures. On real-robot tasks, it improves success rate over the strongest baseline on each task by an average of 21 percentage points.

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Language models

Reinforcement learning with verifiable reward causes unbounded language drift in LLM reasoning chains

The authors investigate language drift in LLM chains of thought during reinforcement learning with verifiable reward (RLVR) post-training. They prove that RLVR permits unbounded drift, unlike supervised fine-tuning which has a finite upper bound, and that limiting drift limits reward. Empirically, drift arises specifically on novel reasoning tasks where the target behavior cannot be drawn out of the base model, and different RLVR runs develop unique drifts.

·2 min
Generative media

Video RL improves by assigning credit to individual visual tokens

The authors introduce TVRL, a framework that derives token-level credit for video reinforcement learning from the same reward signal. By using gradient magnitudes from a frozen vision-language model's question-answer likelihood, they reweight denoising log-probabilities, leading to a 3.60 point improvement on VBench-2.0 Overall score over the base model and consistent gains across multiple samplers and reward models.

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Vision

World model forecasts future 3D geometry directly without recursive rollouts

Noori et al. propose GeoWM, a world model that predicts future scene geometry directly in explicit 3D space rather than in pixel or latent space. The model extracts geometric features from observed RGB frames using a geometry foundation model, then uses a horizon-conditioned flow-matching diffusion transformer to forecast depth, camera pose, and 3D point clouds at a specified future time without autoregressive recursion. On four datasets spanning driving, aerial flight, and robotic manipulation, GeoWM outperforms existing world models by 4 to 58 percent in depth error at short horizons and 7 to 48 percent at long ones, while reducing inference time by about 98 percent.

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Vision

Multi-perspective self-verification improves vision-language model answer reliability

Zhu et al. systematically analyze how verifier capability and prompt design affect self-verification in vision-language models (VLMs), finding that stronger verifiers are more reliable and no single prompt dominates across tasks. They propose MOTIVE, which evaluates candidate answers from multiple verification perspectives and learns a correctness-aligned reliability score to guide accept-or-rethink decisions, consistently outperforming strong self-verification and self-correction baselines.

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Robotics & embodied AI

Human-like scripted demonstrations reproduce behavioral cloning’s puzzling failures

Park and Levine introduce OCBench, a simulated robotic manipulation benchmark designed to reproduce behavioral cloning phenomena that usually appear only with costly human-collected data. By generating narrow, history-dependent and smoothly varying trajectories, the benchmark reproduces four reported anomalies, including benefits from overfitting and action chunking, while allowing candidate explanations to be tested under controlled conditions.

·2 min
Generative media

Generating B-roll footage grounded in a user's captured video collection.

The authors introduce MemComposer for collection-grounded B-roll generation. Given a user's video collection, a natural-language directive, and a target duration, the system builds a structured memory of characters, settings, objects, and style, then retrieves conditioning frames and generates a multi-shot sequence. In a user preference study, MemComposer significantly outperforms ungrounded text-to-video planners on both prompt adherence and visual alignment to the collection.

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Speech & audio

Metadata-supervised pretraining lets encoder-free speech LLMs identify speakers and emotions

The authors propose metadata-supervised pretraining (MSP) for encoder-free speech LLMs, using speaker identity and emotion labels to train models that directly process Mel-spectrograms. On joint ASR and speaker diarization, their model outperformed a randomly initialized encoder-based baseline under matched training data and was competitive with encoder-based models pretrained on much larger datasets.

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Vision

Aligning partial point clouds to frozen global 3D encoders without labels

Adeniran-Lowe et al. show that state-of-the-art 3D encoders, pretrained on globally reconstructed scenes, fail catastrophically on partial viewpoint-dependent point clouds (drop from 72.47 to 2.57 mIoU), primarily due to coordinate-frame mismatch rather than missing geometry. They propose PAGER, a parameter-efficient, label-free adaptation that aligns partial-view features with a frozen global semantic representation using only paired partial/global geometry. On ScanNet partial views, PAGER achieves 65.46 mIoU without any semantic labels, outperforming supervised fine-tuning baselines, and in zero-shot transfer to ScanNet++ it surpasses a fully fine-tuned Sonata encoder (53.93 vs. 48.09 mIoU).

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Reinforcement learning

Posterior rewards become indistinguishable for long reasoning traces in LLM training

Kao et al. show that in verifier-free reinforcement learning for LLMs, the posterior probability of a correct answer conditioned on a reasoning trace collapses to a low-variance interval as the trace lengthens, making rewards nearly indistinguishable. This undermines group-relative policy optimization like GRPO, which relies on reward differences across rollouts. The authors propose RLCPR, which improves stability and token efficiency via uncertainty-aware sampling and concentration-aware regularization, outperforming existing baselines by up to 4 percentage points on six benchmarks.

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Vision

Content-based frame identities unify 3D reconstruction and point tracking

Fradlin et al. present ARROW, a feed-forward model that reconstructs scene geometry and tracks 3D points using arbitrary collections of RGB observations, including videos, static images and multiple camera streams. Its central mechanism assigns each observation a content-derived identity rather than a sequence position, allowing queries to address source, target and reference images without imposing temporal order. The authors report state-of-the-art results on two 3D tracking benchmarks while retaining competitive reconstruction performance.

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Reinforcement learning

RL training runs can yield stronger policies than their best checkpoints

The authors show that a completed reinforcement learning (RL) training history contains structure that can be exploited to construct policies stronger than any checkpoint visited during training. They propose SURGE, which spectrally decomposes the weight updates from a high-accuracy anchor checkpoint and a competitive donor checkpoint, retaining the anchor's dominant component while incorporating complementary information from the donor. The method achieves state-of-the-art results on multiple reasoning benchmarks, exceeding the best native checkpoint without additional training or per-query inference cost.

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Evaluation & benchmarks

OOD detection gains mostly reflect dataset identity, not novelty

Lee and Kang measured how much of the reported out-of-distribution detection gain survives when the detector is tested on an OOD dataset it has never seen—not just on held-out samples of the same dataset. They find that most of the gain comes from recognizing which dataset the input belongs to, not from detecting novelty per se, and they derive a closed-form formula that predicts the inflation without needing a separate hold-out set.

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Evaluation & benchmarks

Random rewards reveal three stages of LLM capability development

The authors explain the spurious-reward paradox—why random rewards improve LLM performance—by introducing reachability, the potential for further training to elicit dormant capabilities. Applying random-reward RL to OLMo checkpoints across training, they find three distinct regimes of responsiveness: early pre-training (dormant), later pre-training (receptive), and mid-training (autodidactic). The pattern reveals that capabilities not yet expressed in current accuracy can be activated by training, even without correctness feedback.

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Evaluation & benchmarks

Most video benchmarks fail to actually test video understanding

Song et al. introduce the attack pyramid, a five-level hierarchy of shortcut attacks that exploit different information sources (options, text, other items, single frames, or shuffled video). Applying it to 115 video benchmarks, they find that on 35 benchmarks attackers that never see a frame achieve full-video accuracy, and on 51 benchmarks with temporal probes, shuffled frames retain a median of 96% of the full-video accuracy. They screen 505,518 question-answer pairs to produce Video-Index, a meta-benchmark of the 840 hardest verified items, and show that even the best evaluated system (Claude Opus 5 with agent tools) leaves significant room for improvement.

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Efficiency & systems

Learned controller adapts speculative decoding to maximize speed and reduce waste

The authors introduce APEX, a learned controller that dynamically selects the speculative decoding mechanism (EAGLE-3, n-gram, or a draft model) and adapts draft depth at each verification block to balance throughput and wasted computation. Evaluated with Qwen3-8B across six workloads, APEX achieves up to 5.24x wall-clock speedup over autoregressive decoding, and its depth-optimizing variant reduces wasted-token percentage by 41% relative to fixed n-gram speculation at depth 16.

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Robotics & embodied AI

Inverse dynamics helps visual world models retain unstable control modes

Toso and colleagues identify a control failure hidden by standard JEPA training: accurate next-step prediction and anti-collapse regularization can coexist with representations that erase unstable but controllable dynamics. They propose endpoint inverse dynamics, which reconstructs an action sequence from the initial and final latent states, and prove that exact reconstruction preserves every state direction reachable within the training horizon.

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Robotics & embodied AI

Synthetic views make robot policies more tolerant of pose errors

Wistreich and colleagues introduce an offline augmentation framework that converts demonstrations recorded at one canonical robot pose into physically consistent examples at perturbed poses. Across simulated humanoid and bimanual tasks, plus experiments on a real Galaxea R1 Pro, policies trained with these examples were more robust to unseen base-position and camera-viewpoint shifts than the tested baselines.

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Agents

Auditable world-model harness achieves perfect ARC-AGI-3 score

The authors present Kepler, an open-source harness for ARC-AGI-3 that represents agent hypotheses as executable world models and validates them through retrodiction and prediction checks. Under a frozen Claude Opus 5 configuration, Kepler achieved a server-verified 100.00 RHAE on all 25 public games, with 181 of 183 completed levels using no more actions than the median-human baseline. The paper also reports three evaluation failures—source-code leakage, autonomous tool reconstruction, and silent planner repair—that score-only evaluation would have missed.

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