NeurIPS 2026 论文列表

Conference on Neural Information Processing Systems

录用类型

6,437篇论文

按官方录用论文列表统计,可能与会议公布的数字略有出入。

  • Oral
    991.5%
  • Spotlight
    2403.7%
  • Poster
    6,09894.7%

浏览全部论文

主题: 扩散模型 · 661 篇论文 · 重置筛选

Beyond Node Sequences: Relational Diffusion for Unified Graph Learning

Xianan Wang, Wenji Hu, Chunyu Wei, Yueguo Chen

展开摘要

Graph foundation models have emerged as a promising paradigm for generalizing across diverse structural tasks. Current approaches serialize graphs into node token sequences and apply autoregressive or masked prediction, yet this node sequential modeling disrupts the relation-centric nature of graphs and violates permutation equivariance. We propose **relational diffusion**, a framework that reconceptualizes graph modeling through edge co-occurrence modeling. By treating edges as fundamental modeling units and learning their joint distribution via discrete diffusion processes, our approach naturally respects the relational semantics of graphs while maintaining permutation equivariance. We introduce topological edge tokenization to enrich edge representations with multi-hop structural context, and relational prompt completion to unify node classification, link prediction, and graph classification as sequence completion problems over edge representations. Through extensive experiments, we demonstrate that relational diffusion achieves strong performance while providing a principled foundation aligned with the relational nature of graphs.

Poster
Beyond MMSE: Enhancing PnP Restoration with ProxiMAP

Kenta Vert, Giacomo Meanti, Scott Pesme, Michael Arbel, Julien Mairal

展开摘要

Plug-and-Play (PnP) methods have become standard tools for solving imaging inverse problems by replacing the intractable maximum a posteriori (MAP) denoiser with the MMSE one. While this mismatch has been widely treated as unavoidable, recent works have sought to close this gap by targeting the MAP with diffusion-model scores. We show this is problematic in practice: learned scores do not match the true ones, so MAP-targeting iterations converge to cartoon-like images rather than realistic ones, and better results are obtained by stopping short of convergence. We turn this observation into a design principle and introduce $\texttt{ProxiMAP}$, an iterative MAP approximation whose noise schedule keeps the iterate's residual noise matched to the denoiser's training noise. This keeps the denoiser in-distribution where its score is reliable, and yields implicit early stopping that avoids the failure mode above. $\texttt{ProxiMAP}$ is a modular drop-in replacement for MMSE denoisers in standard PnP algorithms and consistently sharpens reconstructions across deblurring, inpainting, super-resolution, and phase retrieval. Building on the same principle, we propose a hybrid variant that applies $\texttt{ProxiMAP}$ only in the late iterations of PnP, where the denoiser is most reliable—matching or exceeding the full-replacement variant at a fraction of the cost.

Poster
Beyond Local Neighborhoods: Fractional Diffusion with Levy Flights on Simplicial Complexes for Link Prediction

Jaidev Goel, Yuzhou Chen, Konstantin Avrachenkov, Yulia Gel

展开摘要

Owing to enhanced capabilities to capture a broad range of higher-order interactions, simplicial neural networks (SNNs) have emerged as a new powerful methodology for graph learning. However, prevailing SNNs are often limited in efficient exploration of heterogeneous graphs, thereby restricting the SNN utility on downstream tasks. To address this challenge, we introduce the concept of L\'{e}vy flights over simplices, offering a new efficient alternative to learning higher-order graph (sub)structures under heterogeneous scenarios. Specifically, we develop a new Fractional Hodge Laplacian Simplicial Neural Network (FHL-SNN), a novel approach leveraging fractional powers of the Hodge-Laplacian and allowing for a more efficient exploration of the underlying higher-order graph organization in conjunction with the link prediction. We establish a theoretical connection between a fractional diffusion process and graph exploration over simplices. In particular, we prove that the L\'{e}vy flight over simplices yields a lower mixing time than that of its non-fractional counterpart. Our extensive experiments on both directed and undirected link prediction tasks illuminate the power of non-local search of graph space via fractional dynamics, yielding relative gains of up to 9\%. Finally, we show that the idea of L\'{e}vy flights over simplices is versatile and that the integration of fractional dynamics to existing SNNs has the potential to further boost the model performance.

Poster
Beyond Generation: Unlocking Discriminative Representations from Diffusion Models

Haowen Cui, Ge Wu, Shuo Chen, Yikai Ge, Ge Gao, Xiang Li, Jun Li, Jian Yang

展开摘要

Recent advancements in generative models have increasingly leveraged self-supervised visual representations to guide the synthesis process, significantly improving generation quality and semantic consistency. However, the reverse paradigm of harnessing the generative process to enhance visual representations remains largely underexplored. In this paper, we investigate the semantic properties of class tokens synthesized by generative models. We observe that generative models equipped with representation entanglement can generate class tokens that exhibit stronger discriminative capabilities than those extracted from the original pretrained visual models. Motivated by this observation, we propose a completely new Generation-to-Perception Knowledge Distillation (GPKD) framework, where our method generates class tokens as teacher signals to instill global semantics into the student model. To prevent the degradation of local details, we further incorporate a new masked patch-level distillation objective. This dual distillation strategy enhances global representations while mitigating the forgetting of local details, thereby producing more robust representations. Extensive experiments demonstrate that GPKD obtains consistent improvements across various downstream tasks compared with the base visual encoder, achieving a gain of more than 2\% in $k$-NN accuracy on ImageNet-1K.

Poster
Beyond Distribution Matching: Self-Supervised Representation Forcing for Few-Step Video Generation

Junyi Chen, Haiyu Zhang, Zhoujie Fu, Tengfei Wang, Chunchao Guo

展开摘要

Few-step distillation is essential for deploying modern video diffusion models, and Distribution Matching Distillation (DMD) has emerged as a leading paradigm due to its strong output-space fidelity and its flexibility in supporting both bidirectional and causal student architectures. We find, however, that DMD has a structural blind spot: its objective lives entirely in the output space and provides no signal pushing the student to form a structured internal representation. As the step count shrinks, this output-only supervision becomes too coarse, and the distilled student degrades on both fine spatial structure and coherent temporal dynamics. To close this gap, we introduce Representation-Forcing, which adds a predictive representation loss on top of DMD without changing its output objective. By feeding the student and an EMA teacher with heterogeneous noise levels, we create an information asymmetry that forces the student to predict the teacher's representation from a more corrupted view --- explicitly bringing "representation compression" to distribution matching. Experiments show that Representation-Forcing consistently improves both spatial fidelity and temporal coherence. The mechanism is paradigm-agnostic across bidirectional and causal student architectures, requires no external feature extractor, and adds negligible cost.

Poster
Better Source, Better Flow: Learning Condition-Dependent Source Distribution for Flow Matching

Junwan Kim, Jiho Park, Seonghu Jeon, Seungryong Kim

展开摘要

Flow matching has recently emerged as a promising alternative to diffusion-based generative models, particularly for text-to-image generation. Although flow matching places no restriction on the source distribution, most existing systems still inherit a standard Gaussian from diffusion models, and the source is rarely treated as an optimization target at this scale. Recent works have begun to revisit this choice through condition-dependent or learned sources, yet evidence that such designs are effective in modern text-to-image systems—with high-dimensional latents and tightly integrated conditioning—remains limited. In this work, we study condition-dependent source distributions for flow matching along three axes: _why_ source learning helps, through the lens of the intrinsic variance term in the flow-matching objective; _how_ to make it work in modern text-to-image systems, where variance-only regularization and directional source—target alignment are critical for stable end-to-end training; and _when_ it is most beneficial, by connecting source design to recent representational advances in generative modeling and identifying target representation regimes in which learning the source yields the largest gains. Extensive experiments across multiple text-to-image benchmarks, backbones, and scales demonstrate that principled source design yields consistent and robust improvements—including up to $\mathbf{3.01\times}$ faster convergence in FID and $\mathbf{2.48\times}$ in CLIP score—and outperforms representative prior conditioned-source and condition-aware coupling methods.

Poster
Best-of-$N$ Guidance for Test-time Diffusion Alignment

Richard Lee Kim, Yeongmin Kim, Gyuwon Sim, Taekyu Kim, Minsang Park, Il-chul Moon

展开摘要

Diffusion models achieve strong generative performance but often struggle to align generated samples with human preferences measured by a reward model. A simple yet effective algorithm for test-time alignment is Best-of-$N$ (BoN) sampling, which draws $N$ i.i.d. samples from a pre-trained diffusion model and outputs the single highest-reward sample. Despite its empirical success, this procedure is inherently post hoc: reward information is used only for selection after generation, not for improving the reverse diffusion process itself. Consequently, BoN sampling does not improve the average alignment of generated samples and is primarily suited to single-output settings. We propose Best-of-$N$ Guidance (BoNG), a novel method that integrates the principle of BoN sampling directly into the reverse diffusion process. BoNG performs online BoN selection over denoising particles and adjusts the reverse diffusion process to steer the particle population toward higher-reward regions during generation. Specifically, by introducing an asymmetric guidance interaction among denoising particles, BoNG uses the current BoN particle as a guidance signal to the rest of the particle population. This particle-level interaction reshapes the sampling process toward higher-reward regions, enabling BoNG to improve not only the final best sample beyond Vanilla BoN sampling, but also the average quality of generated samples. Over 36 empirical comparisons, BoNG achieves the best performance in 29 cases, ranking first in 80.56\% of the comparisons against SMC and Vanilla BoN sampling. BoNG also supports multi-output capability, showing 1.3$\times$ ImageReward score than the latest sample-based guidance method with 1.6$\times$ speedup.

Poster
Bernoulli Flow Models: Self-Consistent Generative Modeling for Binary Data

Hao Mo, Liying Yang, Shumin Yao, Xinxing Yu, Ajian Liu, Xudong Mao, Yanyan Liang

展开摘要

Binary diffusion models typically require a massive number of function evaluations (NFEs) to generate high-quality samples, making practical inference computationally expensive. Reducing NFEs while preserving sample quality without relying on distillation or additional training remains a significant challenge. However, existing binary diffusion models sequentially define a discrete one-step forward path and subsequently derive the reverse posterior. In low-NFE scenarios that require cross-step sampling, these models incorrectly approximate the true multi-step likelihood using a single-step likelihood formulation, which severely degrades sample quality. To address this fundamental limitation and completely decouple the generative dynamics from fixed discrete time steps, we propose Bernoulli Flow Models (BFM). Rather than building upon sequential one-step Markov diffusion chains, we predefine a unified continuous global Bernoulli probability flow path between data distributions and pure noise, from which we derive analytical closed-form posterior transitions over arbitrary time intervals. Consequently, reducing the inference NFE in BFM is no longer an approximation of skipped discrete steps; it simply requires re-evaluating the analytical posterior on the new time intervals. This eliminates the structural training-inference mismatch inherent to discrete chains, yielding strictly self-consistent low-NFE sampling. Experimental results show that BFM is highly robust to aggressive NFE reduction. On the LSUN Churches 256x256 dataset, a 256-step-trained BFM achieves an FID of 9.31 when sampled with only 16 steps, whereas the state-of-the-art discrete baseline severely degrades to 204.10. BFM also remains competitive with both continuous and discrete generative baselines under standard full-step inference. Ultimately, these results establish BFM as a theoretically rigorous, self-consistent, and practically effective framework for fast binary data generation.

Poster
Bernini: Latent Semantic Planning for Video Diffusion

Chenchen Liu, Junyi Chen, Lei Li, Lu Chi, Mingzhen Sun, Zhuoying Li, Yi Fu, Ruoyu Guo, Yiheng Wu, Ge Bai, Zehuan Yuan

展开摘要

Multimodal large language models (MLLMs) and diffusion models have each reached remarkable maturity: MLLMs excel at reasoning over heterogeneous multimodal inputs with strong semantic grounding, while diffusion models synthesize images and videos with photorealistic fidelity. We argue that these two families can be unified through a simple division of labor: MLLMs perform semantic planning, while diffusion models render pixels from high-level semantic guidance and low-level visual features. Building on this idea, we propose \textbf{Bernini}, a unified framework for video generation and editing. An MLLM-based \textbf{planner} predicts the target semantic representation directly in the ViT embedding space, and a DiT-based \textbf{renderer} synthesizes pixels conditioned on this plan, augmented by text features and, for editing, source VAE features for detail preservation. Because semantics serve as the interface, the planner and renderer can be trained separately and only lightly co-trained, preserving the pretrained strengths of both components while keeping training efficient. To better handle multiple visual inputs, we introduce Segment-Aware 3D Rotary Positional Embedding (SA-3D RoPE), and further incorporate chain-of-thought reasoning in the planner to better transfer understanding into generation. Bernini achieves state-of-the-art performance across a wide range of video generation and editing benchmarks, with the MLLM's pretrained understanding translating into strong generalization on challenging editing tasks.

Poster
Beckmann Transport Models: From Autonomous Flows to One-Step Maps

Lee Kit, Florentin Coeurdoux, Peter Potaptchik, Yilun Du, Michael Albergo, Eric Vanden-Eijnden

展开摘要

We propose an instantiation of flow matching that relies on a time-independent velocity field (an \emph{autonomous flow}) to exactly map between two distributions, so long as the target is singular, i.e.\ supported on a lower-dimensional data manifold. We also show that the one-step generative map associated with this flow is the unique solution of a simple conservation equation, which can be used to learn the map directly from samples. These autonomous flows and maps give a dynamical meaning to the flux constraint of Beckmann's transportation problem. Their construction provides a unifying framework that recovers, for instance, the closed-form Poisson-flow generative model and equilibrium matching with a quadratic flow-matching regression loss. We illustrate how this theory corrects inconsistencies in existing methods and improves their performance on large-scale image generation.

Poster
Baton: Explicit Semantic Blueprints for Joint Video-Audio Generation

Shuyuan Tu, Qi Tian, Zihan Yang, Yue Wu, Xintong Han, Weijie Kong, Jiangfeng Xiong, Jian-Wei Zhang, Zhao Zhong, Liefeng Bo, Zuxuan Wu, Yu-Gang Jiang

展开摘要

Current open-source diffusion models struggle to generate stable and synchronized audio-visual content, particularly in scenarios demanding complex semantic reasoning. The root cause is that existing methods rely on coarse text embeddings from off-the-shelf encoders to guide audio-video denoising, which discards fine-grained semantics and, critically, lacks a shared long-horizon plan, leading to uncoordinated denoising trajectories and fragile cross-modal alignment. We propose Baton, the first framework that introduces explicit semantic planning into joint video-audio generation. Our key insight is that complementing coarse text guidance with semantically rich, modality-aware planned tokens, jointly reasoned and mutually aligned before denoising, can simultaneously restore fine-grained semantic detail and establish a shared blueprint that coordinates both audio and video denoising trajectories. Concretely, Baton first introduces the VA-Planner, a multimodal language model equipped with dual semantic alignment towers, where learnable queries cross-attend to both video and audio features to produce a pair of semantically aligned video and audio planning tokens as keyframe-level blueprints. These planning tokens are injected into the diffusion backbone via cross-attention layers, providing temporally grounded guidance complementary to coarse text embeddings. Since planning tokens do not share one-to-one spatial-temporal correspondence with diffusion latents, we further propose Relative Semantic RoPE, a relative positional encoding that maps planning tokens and latents into a shared spatial-temporal coordinate frame, enabling each latent to accurately attend to its positionally corresponding semantic cues. Experiments on benchmarks show the effectiveness of Baton both qualitatively and quantitatively.

Poster
B[FM]$^2$: Brain Foundation Model via Flow Matching with SplitUNet

Jaedong Hwang, Kathleen Zhang, David Dai, Konstantinos Kontras, Maarten De Vos, Ila Fiete, Paul Liang

展开摘要

EEG foundation models can learn generalizable representations from large-scale EEG corpora to enable single-backbone transfer across diverse clinical and brain-computer interface tasks. Existing models typically discretize the continuous multi-channel EEG waveform into patches or codebook tokens and train a transformer with masked self-supervision. Recognizing that this discretization fragments continuous brain rhythms and obscures fine-grained temporal dynamics, we present B[FM]$^2$ (Brain Foundation Model via Flow Matching), which drops discretization and pretrains directly on the raw signal using continuous-time flow matching without patches, tokenization, or masking. However, multi-channel EEG signals pose an architectural challenge for flow matching: time is densely sampled and highly autocorrelated (thousands of timepoints), while the electrode axis is short (tens of channels) at distinct scalp positions. To address this time-electrode asymmetry, we introduce SplitUNet, a velocity network that factorizes each block into separate 1D temporal and 1D electrode convolutions and downsamples only along time, preserving electrode topology throughout the hierarchy. B[FM]$^2$ sets a new state of the art on $7$ of $9$ standard downstream EEG classification tasks, using a pretraining budget of only $36{,}895$ segments ($\approx 307$\,h), a fraction ($\approx 3.3$\%) of that required by existing EEG foundation models. It also produces synthetic EEGs that two board-certified neurologists cannot distinguish from real EEGs (Cohen's $\kappa = -0.096$).

Poster
AudioCALM: Continuous Autoregressive Language Modeling for Universal Audio Generation

Huadai Liu, Kaicheng Luo, Wen Wang, Qian Chen, Bin Ma, Xiangang Li, Wei Xue

展开摘要

Unifying speech, sound, and music generation in one model is hindered by tradeoffs between fidelity, end-to-end training, in-context conditioning, and variable-length synthesis that no current paradigm fully resolves. To address this challenge, we present **AudioCALM**, a universal audio generation framework that extends autoregressive (AR) next-token prediction from discrete tokens to continuous audio latents: a thin flow-matching head replaces the softmax to predict rectified-flow velocities at each position, and a block-causal AR-Flow attention pattern produces arbitrary-length output. Joint training of multiple audio generation tasks faces an asymmetric text--audio mismatch: speech transcripts align to specific time spans and demand \textit{tight, time-aligned} attention, whereas sound and music captions describe only overall semantics and rely on diffuse, holistic attention; mixing the two disproportionately degrades sound and music generation. We address this asymmetry at two levels: a \textbf{data reformulation} strategy that unifies all three tasks under a single description-style conditioning interface, and a novel architecture Asymmetric Mixture-of-Modality-Experts (A-MoME), which adds a dedicated residual expert for speech while sound and music share the backbone, incurring no inference overhead on non-speech inputs. Experimental results demonstrate that AudioCALM matches modality-specific state-of-the-art and outperforms prior unified baselines on speech, sound, and music generation benchmarks.

Poster
Attention-Discounted Adaptive Sampler for Masked Diffusion Language Models

Yusuf Sahin, Ahmed R Saikia, Volkan Cevher, Paolo Favaro

展开摘要

Masked diffusion language models can reduce inference steps by revealing multiple tokens per denoising iteration, but this parallelism is fragile: positions that are individually confident may be unsafe to commit together when their predictions are coupled. Existing training-free samplers such as Top-\(k\), Fast-dLLM, and EB-Sampler mainly control how many tokens to reveal, while often ranking candidates by token-wise scores that ignore interactions within the selected set. We propose ADAS, a training-free reranking rule for parallel masked diffusion decoding. ADAS leaves the base sampler's stopping rule unchanged and modifies only subset construction: it greedily discounts a candidate when it attends strongly to already selected positions whose predictions remain uncertain. Unlike graph-constrained methods that turn attention into hard compatibility constraints, ADAS keeps attention continuous and uses it as a soft marginal penalty. Across LLaDA-8B-Base and Dream-7B-Base on GSM8K, MATH500, HumanEval, and MBPP, plugging ADAS into Top-\(k\), Fast-dLLM, and EB-Sampler improves low-NFE performance at matched denoiser evaluations by \(9.11\) and \(10.46\) percentage points on average, respectively, with \(3.1\%\) per-forward runtime overhead. These results show that soft attention-discounted reranking is a simple and modular way to improve quality in highly parallel decoding for masked diffusion language models.

Poster
Attention-Based Sampler for Diffusion Language Models

Yuyan Zhou, Kai Syun Hou, Weiyu Chen, James Kwok

展开摘要

Auto-regressive models (ARMs) have established a dominant paradigm in language modeling. However, their strictly sequential sampling paradigm imposes fundamental constraints on both inference efficiency and modeling flexibility. To address these limitations, diffusion-based large language models (dLLMs) have been proposed, offering the potential for parallel sampling and flexible language modeling. Despite these advantages, current dLLMs sampling strategies rely primarily on token level information, which fails to account for global sequence structure and often yields suboptimal results. In this paper, we study the sampling order selection problem from the perspective of log-likelihood maximization. We show that this problem is NP-hard and propose an optimal sampling-rank-based approximation that makes the objective computationally tractable. We further prove that the tractable objective is optimized by sampling tokens in descending order of their attention-matrix column sums. This finding provides a principled justification for attention-guided sampling and offers a theoretically grounded alternative to greedy search. We instantiate this theoretical insight in a new training-free sampling algorithm, termed Attn-Sampler, and further propose dynamic attention thresholding for practical acceleration. Extensive experiments across multiple benchmarks validate the effectiveness of our proposed method, demonstrating that it achieves superior generation quality while enhancing the sampling parallelism.

Poster
Attend Locally, Remember Linearly: Linear Attention as Cross-Frame Memory for Autoregressive Video Diffusion

Kunyang Li, Mubarak Shah, Yuzhang Shang

展开摘要

Autoregressive (AR) video diffusion is a powerful paradigm for streaming and interactive video generation. However, its reliance on softmax self-attention leads to quadratic compute complexity in sequence length and increasing memory usage due to key-value caching, which fundamentally limits its scalability to long video horizons. Existing remedies (e.g., sparse attention and KV-cache compression) reduce per-step cost but still rely on a linearly growing cache or irreversibly discard past context, and thus fail to simultaneously address linear memory growth and streaming context management. To address this scalability bottleneck, we propose ARL$^2$ (Attend Locally, Remember Linearly), a hybrid attention module that replaces quadratic cross-frame attention with a fixed-size recurrent state. Specifically, we decompose self-attention into two branches: an intra-frame softmax branch for spatial detail and local dependencies, and an inter-frame gated recurrent linear branch that maintains a fixed-size state for streaming context. Our key insight is that softmax attention captures fine-grained local interactions, while a recurrent state provides a controllable mechanism for long-range memory. This design achieves linear-time scaling with constant memory while improving temporal consistency over the full-softmax model. To prevent noisy intermediate states from corrupting long-range memory, we update the recurrent state only after the denoised pass. To avoid within-frame information asymmetry, all tokens share the same pre-update state rather than sequential updates. To the best of our knowledge, this is the first work to convert a pretrained AR video diffusion model into a hybrid linear attention architecture, through an efficient two-stage training scheme adapted to the AR video setting. With 75% of layers replaced by hybrid linear attention, the model achieves up to $2.26\times$ wall-clock speedup and 54% memory reduction, while maintaining comparable quality with improving temporal consistency.

Poster
AtlasVid: Efficient Ultra-High-Resolution Long Video Generation via Decoupled Global-Local Modeling

Ziyang Mai, Yuyao Zhang, Yu-wing Tai

展开摘要

Recent diffusion-based video generators have achieved remarkable visual fidelity and prompt controllability, yet scaling them to ultra-high-resolution (UHR) long videos remains prohibitively expensive. The difficulty is especially pronounced for long single-shot generation where a continuous scene must preserve global temporal coherence, and fine-grained spatial details without relying on clip transitions or autoregressive shot stitching. In this work, we revisit this challenge from the perspective of decoupled modeling. We argue that existing video diffusion models already encode strong local visual priors, while the main bottleneck lies in efficiently extending global spatiotemporal modeling as resolution and duration increase. Based on this insight, we propose AtlasVid, a decoupled global-local framework for efficient UHR long video generation. AtlasVid first generates a low-resolution and low-FPS global semantic proxy via temporally scaled RoPE, thereby extending the temporal horizon without increasing the training token count. Guided by this proxy, a high-resolution detail branch performs joint denoising with hierarchical locality-preserving attention. Reordered spatiotemporal windows preserve geometric locality and asymmetric global-local attention injects aligned semantic guidance and preserves the model's pretrained ability. This design enables resolution-agnostic training: the model is trained only at 720P with lightweight LoRA adaptation, yet generalizes directly to 4K and beyond for longer (>10s) video synthesis. Experiments show that AtlasVid substantially improves the efficiency of ultra-high-resolution long video generation, achieving high-quality UHR long video generation with $60.9\times$ speed up and significantly less training cost and even better performance than native 4K video generators.

Poster
AsymHP: Load-Balanced Sparse Attention for Video Diffusion Transformers

Xinwei Qiang, Yue Guan, Ruihan Zhu, Mihir Jagtap, Zaifeng Pan, Zhongkai Yu, Chang Chen, Zhengding Hu, Yufei Ding, Adnan Aziz

展开摘要

Video diffusion transformers rely on self-attention over long spatio-temporal token sequences, making inference expensive even when sparse attention reduces the number of computed blocks. This paper studies a systems bottleneck that appears in dynamic sparse video attention: per-head sparsity can vary widely across denoising steps, layers, and prompts, so equal-head parallel execution leaves some GPUs waiting for dense heads assigned to other GPUs. We propose AsymHP, a runtime system that uses the previous denoising step's per-head sparse density to place a non-uniform number of heads on each GPU. AsymHP combines this lightweight online density estimate, a cost model for mask construction and sparse attention computation, and an asymmetric head redistribution primitive that avoids padding variable-size head shards into symmetric collectives. In our evaluation on H100 GPUs, AsymHP improves sparse attention latency by up to $1.54\times$ without changing the underlying sparse-attention algorithm.

Poster
Are we really tilting? The mechanics of reward guidance in flow and diffusion models

Sanjit Dandapanthula, Nicholas Boffi

展开摘要

Reward guidance algorithms steer a learned generative process toward the reward-tilted measure at inference time. While empirically powerful, these methods are prone to reward hacking: the guided model over-optimizes the reward at the cost of fidelity to the learned distribution. Prior work has attributed this to the complexity of neural reward functions or implicit biases in diffusion training, but its fundamental origins remain poorly understood. We show that reward hacking arises from an approximation made in most practical implementations of reward-guided diffusion---finite-particle plug-in estimation of the Doob $h$-function---even in the simplest non-trivial settings of Gaussian and Gaussian mixture targets with quadratic rewards. In closed form, we isolate two distinct failure modes of the plug-in estimator: it leads to reward hacking within each mode and it cannot select high-reward modes. We propose a closed-form reward damping schedule that corrects the within-mode bias with no additional compute, and clarify the role of best-of-$n$ sampling in compensating for the mode selection failure. Experiments on Gaussian mixture targets, a 2D checkerboard, and FLUX.1 text-to-image generation confirm that our theoretical insights carry over to practical settings.

Poster
Arbitrarily Conditioned Hierarchical Flows for Spatiotemporal Events

Keyan Chen, Qiwei Yuan, Zhitong Xu, Bin Shen, Shandian Zhe

展开摘要

Events in spatiotemporal systems are ubiquitous, yet modeling their complex distributions remains challenging. Existing point process models often rely on strong structural assumptions and are typically limited to autoregressive, event-by-event prediction. As a result, they struggle to support broader inference tasks such as inverse inference, trajectory reconstruction, and recovery of missing event locations. We introduce Arbitrarily Conditioned Hierarchical Flows (ARCH), a hierarchical flow matching framework for spatiotemporal event modeling. ARCH is expressive enough to capture complex event distributions while enabling tractable and accurate computation of conditional intensities, which quantify instantaneous event risk. Built on a history-encoder-generative-decoder architecture, ARCH introduces a hybrid masking strategy for flexible conditioning on arbitrary observed events. This enables a unified treatment of forecasting, inverse inference, and partial trajectory recovery within a single framework. Experiments on synthetic and real-world datasets show that ARCH consistently outperforms existing baselines across both prediction and conditional inference tasks.

Poster