NeurIPS 2026 Papers

Multi-modal image fusion is crucial for comprehensive scene representation, yet real-world degradations compromise its efficacy, necessitating degradation-robust fusion paradigms. Existing degradation-robust multi-modal image fusion methods are often hindered by cascaded sub-optimal solution or black-box opacity. To address these challenges, we propose a theory-inspired mutual-promoting deep unfolding framework. It reformulates degradation-robust image fusion as a joint optimization problem, utilizing the degradation model and modality generation mechanism to explicitly model both single-task priors and cross-task dependencies. By decomposing the complex multi-task optimization problem into task-related iterative subproblems, the framework establishes a bidirectional reciprocal information flow between restoration and fusion. This process is further unfolded into a multi-stage deep neural network, where each component explicitly corresponds to a specific mathematical operation. In our framework, the fused cross-modal prior actively regularizes the ill-posed restoration, while the purified modality features continuously refine the fusion output. It ensures a transparent architecture that combines the merits of both model-based and data-driven methodologies. Extensive experiments demonstrate that our paradigm achieves state-of-the-art performance while providing superior interpretability.

Multi-objective Bayesian optimization (MOBO) traditionally aims to approximate the entire Pareto front, but real-world deployment is often limited to a small, representative subset of solutions due to resource constraints. Current two-stage methods first approximate the full front before selecting solutions, wasting evaluation budget. We formalize this problem as Multi-objective Bayesian Optimization with Cardinality-aware Pareto Selection (MOBO-CAPS), where the goal is to identify a set of exactly $M$ solutions with high hypervolume. We propose two practical cardinality-aware acquisition strategies: REHVI, a replacement-aware approximation to expected hypervolume improvement, and CHO-UCB, which constructs an optimistic $M$-point set by optimizing a collective UCB-based hypervolume objective. We prove a sublinear simple regret bound for the batched version of CHO-UCB, and empirically show that cardinality-aware acquisition design improves over standard MOBO followed by post-hoc subset selection across nine benchmarks.

Multimodal large language models (MLLMs) provide a promising alternative by taking object detection as a sequence generation task. However, applying MLLMs to multimodal object detection poses challenges in visual cross-modal (RGB-Infrared) fusion and coordinate prediction under Cross-Entropy supervision. In this paper, we propose a novel MLLM-based object detection framework that addresses these challenges through improving visual cross-modal token alignment and coordinate generation. Specifically, we formulate RGB-IR fusion as pre-decoding token-space modality routing, implemented by the Cross-Modal Complementary Adapters and the Visual Token-wise Router. We further reformulate coordinate-token learning as scale-adaptive neighborhood likelihood maximization through our proposed Geometry-Aware Loss, bridging discrete token prediction and continuous geometric localization. Extensive experiments show that our method achieves state-of-the-art performance, reaching 67.81\% mAP@0.5 under in-distribution scenarios, outperforming existing baselines by over 8\%, while also exhibiting strong generalization to out-of-distribution and referring object detection tasks.

Multi-server MCP agents create an information-flow control problem: faithful tool composition can turn individually benign read/write permissions into cross-boundary credential propagation---a structural side effect of workflow topology, not necessarily malicious model behavior. We present MCPHunt, to our knowledge the first controlled benchmark that isolates non-adversarial, verbatim credential propagation across multi-server MCP trust boundaries, with three methodological contributions: (1) canary-based taint tracking that reduces propagation detection to objective string matching; (2) an environment-controlled coverage design with risky, benign, and hard-negative conditions that validates pipeline soundness and controls for credential-format confounds; (3) completion-requires-secret (CRS) stratification that disentangles task-mandated propagation (faithful execution of verbatim-transfer instructions) from policy-violating propagation (credentials included despite the option to redact). Across 3,615 main-benchmark traces from 5 models spanning 147 tasks and 9 mechanism families, policy-violating propagation rates reach 11.5--41.3% across all models. This propagation is pathway-specific (25x cross-mechanism range) and concentrated in browser-mediated data flows; hard-negative controls provide evidence that production-format credentials are not necessary---prompt-directed cross-boundary data flow is sufficient. A prompt-mitigation study across 3 models reduces policy-violating propagation by up to 97% while preserving 80.5% utility, but effectiveness varies with instruction-following capability---suggesting that prompt-level defenses alone may not suffice. Code, traces, and labeling pipeline are released under MIT and CC BY 4.0.

Acoustic sensing is a promising technique for human-computer interaction, but existing learning-based systems still depend heavily on large task-specific labeled datasets. Compared with visual data, acoustic signals are difficult to interpret and annotate, making supervision costly and hard to scale. Meanwhile, existing unsupervised representation learning methods, particularly contrastive learning, are largely designed for natural images and rely on data augmentation to form positive pairs. Such strategies can destroy the temporal-physical structure of acoustic signals, causing shortcut learning rather than meaningful representation learning. To address this issue, we propose MCAS, a signal-processing-based multi-view contrastive learning framework for acoustic sensing. Instead of relying on artificial augmentations, MCAS constructs structure-preserving positive pairs from complementary representations derived from different signal processing pipelines of the same acoustic event. Moreover, MCAS is designed to address the heterogeneity of acoustic representations through progressive cross-view interaction enabled by Hierarchical Shared-Token Fusion and a multi-level pretraining objective with physical consistency regularization. Extensive experiments on two typical acoustic sensing tasks demonstrate the effectiveness of the proposed framework. Under low-label settings, MCAS consistently outperforms both supervised baselines and generic self-supervised baselines, while also showing strong cross-task transferability and robustness to corruptions and noise.

Deep clustering struggles when coarse-grained and fine-grained semantics coexist in the same dataset, as a unified partitioning strategy tends to either over-separate coarse categories or miss subtle fine-grained differences. To address this problem, we propose the adaptive multi-granularity clustering framework in a hyperspherical space (MC-H). The framework combines Dynamic Prototype-Center Assignment (DPCA), a Hyperspherical Determinantal Point Process (H-DPP) module that adaptively regulates repulsion according to local structure and promotes stronger separation in dense regions while preserving flexibility in sparse ones, and a Semantic Subspace Denoising (SSD) module that suppresses non-semantic variations and improves cluster compactness. Extensive experiments across datasets with different semantic granularities show that our method consistently outperforms existing approaches and effectively unifies clustering across the full granularity spectrum.

Large language models now produce text indistinguishable from human writing, which increases the need for reliable provenance tracing. Multi-bit watermarking can embed identifiers into generated text, but existing methods struggle to keep both text quality and watermark strength while carrying long messages. We propose MC$^2$Mark, a distortion-free multi-bit watermarking framework designed for reliable embedding and decoding of long messages. Our key technical idea is Multi-Channel Colored Reweighting, which encodes bits through structured token reweighting while keeping the token distribution unbiased, together with Multi-Layer Sequential Reweighting to strengthen the watermark signal and an evidence-accumulation detector for message recovery. Experiments show that MC$^2$Mark improves detectability and robustness over prior multi-bit watermarking methods while preserving generation quality, achieving near-perfect accuracy for short messages and exceeding the second-best method by nearly 30% for long messages.

Multi-objective optimization (MOO) underlies many machine learning problems, yet MOO solvers across the loss-balancing, gradient-balancing, and Pareto-based families almost universally hand their reconciled directions to Adam~\cite{kingma2015adam}. We show this coupling introduces two systematic gaps between the solver's intent and the optimizer's execution. The first is a \emph{weighting mismatch}: Adam's second-moment denominator entangles the time-varying preference vector with gradient statistics, marginalizing the preference into a history average and collapsing distinct Pareto trade-offs toward a near-uniform mixture. The second is a \emph{geometric mismatch}: Adam's adaptive metric distorts the Euclidean geometry MOO solvers assume, turning aligned objectives into apparent conflicts. To resolve both jointly, we introduce \textbf{MAdam} (Metric-Aware Multi-Objective Adam), a drop-in wrapper that leaves both solver and optimizer unchanged. MAdam preconditions the reconciled direction by the preference-conditioned curvature of the scalarized objective; on this whitened input, Adam's second moment collapses to identity, so the realized update is governed by the preference-conditioned metric. Across multi-task learning, Pareto-front recovery, physics-informed neural networks, and medical imaging, MAdam consistently improves over Adam for every solver family.

Aligning large language models (LLMs) with diverse and multifaceted user preferences is a fundamental challenge in personalized AI systems. Existing multi-objective alignment methods either rely on costly training or require pre-trained reward models for each preference, making it difficult for them to adapt to evolving preferences. Prompt-based personalization offers a training-free alternative, but prompting alone often provides limited steerability, as LLMs may overemphasize or overlook certain preferences and fail to give users reliable control over the relative importance of different objectives when conflicts arise, leading to suboptimal alignment. In this paper, we introduce MATO, a training-free framework for Multi-objective personalized Alignment with Test-time Optimization. MATO formulates personalization as a test-time optimization problem that steers the relative importance of multiple objectives through controllable weights during decoding, without modifying model parameters or requiring external reward models. Specifically, a reward discovery module recovers preference rewards directly from the backbone LLM for diverse objectives specified in natural language, while a weight optimization module dynamically adjusts objective weights based on the user's initial preferences and the partially generated response to balance competing objectives during generation. The resulting rewards and weights jointly guide an online optimization procedure over the token distribution, enabling better alignment with the target objectives. Extensive experiments across multiple datasets and backbone LLMs show that MATO consistently outperforms strong baselines, achieving Pareto-improving multi-objective alignment and stronger steerability. These results highlight test-time optimization as a promising direction for scalable, controllable, and model-agnostic personalized alignment.

We introduce **MANGO** (Multi-Angle Neural Gated Operator), a spectral neural operator for chirp-perturbed PDEs whose solutions exhibit a local spectral content that rotates continuously with position. MANGO maintains multiple fractional Fourier transform (FRFT) branches whose angles are learnable parameters, optimized jointly with the spectral weights and a position-dependent softmax gate that combines branches at every spatial location. The architecture is matched to the structure of the problem class: the FRFT at angle $\alpha_0$ diagonalizes the chirp-perturbed PDE whose intrinsic angle is $\alpha_0$, and MANGO's learnable angles let the architecture discover $\alpha_0$ from data when it is unknown or varies across the domain—neither of which classical FRFT methods accommodate. We further introduce a Mihlin–Hörmander regularizer on the spectral weights of each non-Fourier branch, encouraging each branch to act as a bounded operator on $L^p$ for $1 < p < \infty$. We construct four chirp-perturbed PDE benchmarks with closed-form ground truth, positioned as identifiability tests. On these benchmarks, MANGO recovers the intrinsic spectral structure of each PDE from supervised solution data alone and achieves state-of-the-art performance against six neural-operator baselines.

Electroencephalography (EEG) data plays an important role in understanding human brain activity, with various major applications. While current approaches, which largely build on EEG foundation models, have demonstrated strong performance across datasets and tasks, they typically rely on a fixed temporal scale. This design choice limits their ability to capture characteristics of neural dynamic behavior, often spanning across multiple timescales, which are naturally captured in EEG recordings. To address this limitation, we propose MAGE (**Multi-timescale Adaptive Generalization for EEG**), a foundation model that dynamically adapts to capture and integrate information across different timescales. Specifically, MAGE combines two key mechanisms: (i) a novel multi-timescale attention mechanism, capable of learning representations across multiple temporal scales, and (ii) a trainable aggregation module that dynamically identifies and adapts to the most informative timescale of the input signal. Experimental results across seven datasets demonstrate that MAGE consistently outperforms existing EEG foundation models while using substantially fewer parameters. Moreover, our results support the hypothesis that different downstream tasks benefit from distinct temporal scales. All source code will be released.

We study online scheduling in a shared-resource system where tasks of different types arrive sequentially and compete for limited resources. Each task is modeled as an $H$-stage episodic Markov decision process, which captures the sequential resource-allocation decisions made within the task. At the system level, the learner must coordinate resource sharing across tasks to maximize the long-term ratio of cumulative reward to cumulative cost over $K$ tasks, without knowledge of the task distribution. The key challenges are coupled intra-task Markovian dynamics and inter-task ratio maximization, further complicated by unknown models and large or continuous state spaces. To address these challenges, we propose Contextual Optimistic Lyapunov Decomposition (COLD), a Lyapunov-driven optimistic learning algorithm. COLD converts the long-term ratio objective into a queue-adjusted per-task surrogate, thereby decoupling reward-cost optimization from statistical value estimation. It uses double-optimistic least-squares value iteration to estimate reward and cost values under linear function approximation, and a softmax policy to smooth the greedy update with only a controlled approximation error. We prove a regret bound of $\tilde{\mathcal{O}}(\sqrt{Md^3H^3T})$, where $M$ is the number of task types, $d$ is the feature dimension, $H$ is the episode horizon, and $T=KH$ is the number of interaction steps. The $\sqrt{T}$ dependence is order-optimal up to logarithmic factors, and the bound scales with the feature dimension rather than the size of the state space. Experiments on synthetic environments and an empirical KuaiRand-based MDP demonstrate the effectiveness of the proposed method.

Multi-objective reinforcement learning (MORL) aims at optimising several, often conflicting goals to improve the flexibility and reliability of RL in practical tasks. This is typically achieved by finding a set of diverse, non-dominated policies that form a Pareto front in the performance space. However, constructing such a policy set remains computationally demanding, as it requires finding not a single optimal policy, but a set of policies to cover a wide range of trade-offs among the objectives. We introduce LLE-MORL, an approach that traces policy manifolds by utilising the local relationship between the high-dimensional policy parameter space and the performance space. This structured representation enables an efficient search within contiguous solution domains via locally linear extrapolation, allowing for the rapid generation of high-quality solutions without extensive retraining. We also provide a theoretical analysis of the policy manifold structure in order to specify the applicability of the method. Experiments across diverse continuous control domains demonstrate that LLE-MORL consistently achieves higher Pareto front quality and efficiency than state-of-the-art approaches.

Phylogenetic inference, the task of reconstructing how related sequences evolved from common ancestors, is a central objective in evolutionary genomics. The current state-of-the-art methods exploit probabilistic models of sequence evolution along phylogenetic trees, by searching for the tree maximizing the likelihood of observed sequences, or by estimating the posterior of the tree given the sequences in a Bayesian framework. Both approaches typically require to compute likelihoods, which is only feasible under simplifying assumptions such as independence of the evolution at the different positions of the sequence, and even then remains a costly operation. Here we present the first likelihood-free inference method for posterior distributions over phylogenies. It exploits a novel expressive encoding for pairs of sequences, and a parameterized probability distribution factorized over a succession of subtree merges. The resulting network provides well-calibrated estimates of the posterior distribution leading to more accurate tree topologies than existing methods, even under models amenable to likelihood computation. We further show that its edge against likelihood-based methods dramatically increases under models of sequence evolution with intractable likelihoods.

We study the sequential decision-making problem where at each time the learner selects an assortment of bounded size and receives a ranking of the selected items. Ranking feedback arises naturally when human evaluators or automated LLM judges compare multiple options simultaneously. It is often easier and more reliable than assigning absolute scores, which are typically poorly calibrated across evaluators, while yielding substantially more information than a single pairwise comparison. We focus on rankings that are constructed according to the random utility model with linear utilities, which includes the popular Plackett-Luce model as a special case. We show that improved regret minimisation is possible under full rank breaking with a refined analysis based on 1-factorisations and Baranyai's theorem that fully exploits independence in the pairwise comparisons. This gives a tighter confidence interval around the true utility parameter which is crucial in our analysis for regret that improves with maximum assortment size. Furthermore, it matches the regret lower bound for our model in case the learner is permitted to play multi-sets of the maximum bounded size. Our work gives a principled approach to learning from ranking feedback that shows consistent improvement with the maximum assortment size.

Learning permutations is fundamental to sorting, ranking, and matching, but existing differentiable methods based on entropy-regularized Sinkhorn produce a single softened solution and collapse under ambiguity. We present PermFlow, a conditional flow matching framework that operates directly on the affine subspace of matrices with unit row and column sums. A closed-form tangent-space projector preserves these constraints exactly along every trajectory, by construction rather than through iterative correction, and a nearest-target coupling routes distinct noisy initializations toward distinct valid permutations. The result is a model that captures multimodal permutation distributions rather than collapsing them to a single mode. On a visual sorting task with blended-digit ambiguity and a symmetric linear assignment problem, PermFlow achieves high accuracy on unambiguous inputs and recovers both valid permutations under ambiguity, where Sinkhorn-based baselines structurally fail.

LLM agents, which often comprise parallel inference tasks, are commonly adopted to solve real-world problems. When serving such task-parallel LLM agents in shared GPU servers, the scheduler is expected to attain fast agent completion with guaranteed worst-case performance. For that objective, our insight is to selectively pampering agents based on their completion order under idealized fair-sharing. We design Justitia, a fair and also efficient scheduler for task-parallel LLM agents. Noticing that memory is prevalently a bottleneck in LLM serving, Justitia quantifies the true agent cost in a memory-centric manner. It also adopts a light-weight yet accurate method to predict agent costs. Finally, Justitia adopts a virtual-time based fair queuing algorithm to reduce the overall performance with guaranteed worst-case delay. We have implemented Justitia atop vLLM, and experimental results involving diverse agents show that it can substantially enhance the scheduling efficiency with fairness preserved.

Many optimization problems require balancing multiple conflicting objectives. To generalize gradient descent, which is limited to single-objective optimization, we introduce Jacobian descent (JD) and its stochastic variants. This algorithm iteratively updates parameters using the Jacobian matrix of a vector-valued objective function, in which each row is the gradient of an individual objective. While several methods to combine gradients already exist in the literature, they generally struggle when the objectives conflict. In contrast, we propose projecting gradients to fully resolve conflict. We prove convergence to the Pareto front in the smooth convex case with this approach, a stronger guarantee than the usual convergence to a weakly Pareto stationary point. Our method also enables instance-wise risk minimization (IWRM), a novel learning paradigm in which the loss of each training example is considered a separate objective. Early experimentation on image classification shows promising results for IWRM. Lastly, we provide an efficient implementation of JD using the Gramian of the Jacobian matrix to drastically reduce memory requirements.

Mixed-precision quantization improves the accuracy-efficiency trade-off by assigning different bit-widths across a network. Since bit-width selection is a combinatorial problem, existing methods often optimize additive surrogate losses instead of directly evaluating task losses in all configurations. We show that these surrogates can suffer from surrogate-task mismatch, especially when many layers are changed simultaneously from a reference configuration. We further observe that, although allowing more layers to change improves the surrogate objective, the evaluated task loss can be minimized at an intermediate limit on the number of changed layers. Based on this observation, we propose Iterative Integer Linear Programming (I2LP), which iteratively refines a reference bit configuration. At each refinement step, I2LP solves multiple ILPs with different limits on how many layers may change from the current reference, and accepts the best candidate only when it reduces the task loss. I2LP applies to both post-training quantization and quantization-aware training, and consistently outperforms uniform-precision baselines and existing mixed-precision methods. Code will be released.