Research

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

2566 articles · page 41 of 54 · The Research front page

Reinforcement learning

Online distillation cuts needless verbosity in RL-trained models

The authors identify and quantify the 'length-scaling tax'—excess response length on already-solved problems that arises during reinforcement-learning (RL) post-training. They propose Length Self-Distillation (LSD), which routes solved prompts to on-policy distillation using an exponential moving average of the online policy as teacher, while retaining the original RL objective for unsolved prompts. LSD reduces LST from 19.0% to -3.7% on single-turn reasoning and from 31.4% to 13.7% on multi-turn agentic tasks, achieving comparable or better accuracy than vanilla RL.

Evaluation & benchmarks

Security agents lose evidence support when available telemetry changes

The authors introduce APTInvestBench, a benchmark that tests whether LLM agents can investigate advanced persistent threats when the available security logs change. Across eleven models, agents retrieved sufficient evidence for 44.3% of recoverable attack actions on average, but their final citations adequately supported only 25.0%, revealing substantial losses between finding evidence and reporting it.

Agents

Reusable harness components let agents adapt workflows to each task

Kuang and colleagues argue that a single agent harness is poorly suited to heterogeneous tasks because mechanisms such as verification, context management and termination logic can help in one setting but distract or slow an agent in another. Their STITCH framework composes task-specific harnesses from reusable primitives, improving reported task success by up to 12 percentage points over fixed harnesses while adding 2.7% test-time overhead.

Agents

Selective self-distillation helps LLM judges generalize on subjective evaluations

Hong et al. train LLM judges using preference rationales and rubrics rather than relying only on rewards for correct final verdicts. Their position-selective self-distillation method withholds supervision at tokens where feedback sharply narrows the model toward one expression, improving generalization and outperforming outcome-supervised reinforcement learning by 2 to 9 percentage points on evaluated subjective categories.

Evaluation & benchmarks

Long context windows do not ensure reliable sustained execution

Willette, Puvvada and Ginsburg introduce Long-Transduction, a diagnostic for whether models can repeatedly read state, transform it and emit correctly aligned outputs over long generations. Their experiments show that advertised context capacity does not imply dependable execution: accuracy fell substantially as context grew from 4K to 128K tokens, even though the underlying operations remained controlled.

Vision

Forensic tool use improves explainable zero-shot image forgery detection

Tan et al. present ATAR, an agentic system that investigates images through repeated visual inspection and calls to specialized forensic tools, rather than explaining a classifier’s predetermined output. Across six zero-shot image manipulation detection and localization benchmarks, ATAR achieved an average image-level F1 score of 78.5%, 11.8 percentage points above the strongest multimodal language model baseline evaluated.

Robotics & embodied AI

Simulation-first framework lets coding agents learn real robot skills in 10 minutes

The authors introduce SimEX, a two-stage autoresearch framework that tightly integrates simulation with LLM-based coding agents. In the first stage, the agent conducts open-ended probe-and-optimize iterations in simulation to develop a robust robot toolbox; in the second stage, the toolbox is adapted to a real robot through only a few physical trials, each correcting the simulator and using the corrected simulator to diagnose failures and screen repairs. On three challenging real-world manipulation tasks—towel folding, barcode scanning, and plate manipulation—SimEX achieved success without any demonstrations and with only 10 minutes of real-robot interaction.

Agents

Cross-checking coding agents improves reliability in automated model research

Chen and colleagues present RankEvolve, a harness that automates repeated proposal, implementation, training and evaluation of ranking-model changes while enforcing a predefined experimental process. Their central result is that combining Claude Code and Codex as cross-checking execution nodes raised fully correct execution from 45.8 percent to 62.5 percent, although consequential defects still passed silently in 10.4 percent of cases.

Vision

Visual image rearrangement helps models when exact evidence matters most

Zhang et al. treat multi-image reasoning as a problem of re-representation: reorganising visual evidence so a model can inspect relationships that are difficult to infer from the original images alone. They compare textual reasoning with visual transformations, introduce the grounding-focused MosaicBench, and train MosaicAgent-8B to operate on images. Their central finding is that visual re-representation helps most when answers depend on precise alignment, orientation, or pixel-level comparison, rather than broad semantic interpretation.

Safety & security

Simulated future actions may expose multi-turn agent attacks earlier

Wang et al. propose Speculative Safety Honeypot (SSH), a framework for detecting attacks whose malicious intent is distributed across multiple interactions. Small language models simulate possible future actions in parallel, while the target agent’s actual behavior is used to prune and recalibrate those predictions. The paper argues that this trajectory-level view can warn earlier than detectors limited to completed interaction history.

Evaluation & benchmarks

Clinical agents falter when health records cannot support the question

Qiao et al. built an interactive benchmark from MIMIC-IV records to test clinical agents on paired questions that are either supported by the database or rendered unanswerable by a single evidence discrepancy. Across proprietary and large open-weight models, average task success fell from 62.2% on supported questions to 37.9% on noisy counterparts, showing that retrieval and query execution do not ensure evidence-grounded reasoning.

Evaluation & benchmarks

New benchmark disentangles sycophancy from empathy in multi-turn LLM conversations

The authors introduce FIGS, a benchmark with 500 multi-turn scenarios and an automated judge that separately scores sycophancy (factual yielding) and calibrated validation (appropriate empathy). Evaluating leading LLMs, they find a consistent trade-off: models gradually become sycophantic over sustained conversation, or shift to robotic dismissal, showing that balancing truthfulness with supportiveness remains unsolved.

Safety & security

Method to permanently erase unwanted LLM personas via weight edits

Li et al. introduce persona unlearning, a weight-level edit that makes a designated persona difficult to elicit on unseen prompts. To evaluate this, they construct PersonaUnlearnBench, a paired benchmark over six LLMs and five personas, and propose PaCE, a method that identifies an internal behavior direction and trains target-prompt states away from that mode. PaCE consistently suppresses target personas with high response quality and moderate utility cost.

Vision

Shared scene graphs connect interaction understanding with grounded robot planning

Zhang and colleagues introduce ChronoGraph, a representation that links actions on functional object parts, such as handles, to subsequent semantic and geometric changes in a scene. They use automatically annotated human videos and simulated robot trajectories to train vision-language models to reconstruct past interactions and predict future states, then demonstrate that the resulting plans can guide a mobile manipulator through existing robot skills.