arXiv subjects

Hankyeol Kim

Publications and source records attributed to Hankyeol Kim.

4 recordsLinked to original sources

arXiv2026

Dynamical State-Space Diffusion for Spatiotemporal Prediction

Diffusion models for temporal prediction typically corrupt each future frame with independent noise, leaving temporal dependence entirely to the denoiser. We propose Dynamical State-Space Diffusion (DSSD), which learns the temporal structure of the corruption process itself. DSSD builds a temporal kernel from the damped oscillatory modes of a stable diagonal state-space model, whose learned decay rates and frequencies let the corruption capture multiple timescales and oscillatory correlations, while the denoiser architecture remains unchanged. Running this model on a finite clip, however, requires the state before the first frame, which is unobserved; starting from a zero state leaves the early frames with less noise than the diffusion schedule prescribes. We avoid this by using the Cholesky factor of the model's stationary covariance as the temporal operator. We prove that this operator is causal, exactly invertible, keeps each frame's noise variance equal to that of standard diffusion, and reduces to the identity at the clean end of the process, and that it is exactly the Kalman innovations form of the state-space model. The denoiser is trained to predict the temporally correlated noise, and sampling removes and reapplies the temporal mixing at each step. On scientific-field and robot-video datasets, DSSD outperforms diffusion baselines that share its denoiser, and the evolution of its learned modes during training shows that the temporal operator adapts to each dataset.

cs.CV↗

arXiv2026

Same Answer, Different Confidence: Protocol Sensitivity in LLM Confidence Calibration

Large language models (LLM) can state their confidence in an answer (verbalized confidence), or the confidence can be read from the probability of the answer's tokens (token confidence). Comparisons of the two ask which is better calibrated, but the token probability of an answer depends on the text that precedes it. Across five open LLMs and four question-answering datasets, we fix each answer, its verbalized confidence, and its correctness label, and vary how each score is measured. The scores themselves change with the protocol, and so does the comparison between them. Changing the context in which the token probability is read shifts the gap between the two scores by about the size of the gap itself (.287 vs. .304 in expected calibration error, ECE; .189 vs. .145 in AUROC). The 95% interval of the shift excludes zero in 19 and 17 of the 20 settings, and under AUROC the shift has the same sign in all of them, so the context changes how answers are ranked. The better score flips in 8 settings under each metric, counting only flips that the intervals support, and the shift also appears in four larger models of up to 72B parameters. Most of the shift appears with changes to the instruction, not to the position of the answer. Other measurement choices also matter, and stated confidence depends on how a supplied answer is written. We turn these results into a reporting checklist for LLM confidence and its comparisons.

cs.AI↗

arXiv2026

Oddin: Latent Visual Reasoning in Unified Multimodal Models via Self-Distillation from Image Generation

Unified large multimodal models (ULMMs) are able to perform visual reasoning through interleaved text-image generation, but generating explicit intermediate images incurs significant computational overhead. While visual latent reasoning addresses this, most existing methods rely on vision-language models (VLMs) incapable of visual generation. We propose Oddin, a novel framework enabling latent visual reasoning in ULMMs. Oddin replaces intermediate images with compact latent tokens processed entirely by the understanding branch, reserving the generation branch for the final output image. We train the model via offline self-distillation with three objectives, final image generation losses, text distillation losses, and cross-entropy losses for special tokens. Oddin surpasses interleaved generation baselines and closed-source VLMs on average across seven VBVR-Pro visual reasoning tasks. Qualitative analysis reveals that latent tokens attend to relevant regions in an input image, demonstrating that ULMMs can perform complex visual reasoning without generating intermediate images.

cs.CV↗

arXiv2026

naPINN: Noise-Adaptive Physics-Informed Neural Networks for Recovering Physics from Corrupted Measurement

Physics-Informed Neural Networks (PINNs) are effective methods for solving inverse problems and discovering governing equations from observational data. However, their performance degrades significantly under complex measurement noise and gross outliers. To address this issue, we propose the Noise-Adaptive Physics-Informed Neural Network (naPINN), which robustly recovers physical solutions from corrupted measurements without prior knowledge of the noise distribution. naPINN embeds an energy-based model into the training loop to learn the latent distribution of prediction residuals. Leveraging the learned energy landscape, a trainable reliability gate adaptively filters data points exhibiting high energy, while a rejection cost regularization prevents trivial solutions where valid data are discarded. We demonstrate the efficacy of naPINN on various benchmark partial differential equations corrupted by non-Gaussian noise and varying rates of outliers. The results show that naPINN significantly outperforms existing robust PINN baselines, successfully isolating outliers and accurately reconstructing the dynamics under severe data corruption.

cs.LG↗