Signal Processing
WaveC2R: Wavelet-Driven Coarse-to-Refined Hierarchical Learning for Radar Retrieval
Chunlei Shi, Han Xu, Yinghao Li et al. (+4 more)
Satellite-based radar
retrieval methods are widely employed to fill coverage gaps in ground-based radar systems, especially in remote areas affected by terrain blockage and limited detection range. Existing methods predominantly rely on overly simplistic spatial-domain architectures constructed from a single data source, limiting their ability to accurately capture complex precipitation patterns and sharply defined meteorological boundaries. To address these limitations, we propose WaveC2R, a novel wavelet-driven coarse-to-refined framework for radar
retrieval. WaveC2R integrates complementary multi-source data and leverages frequency-domain decomposition to separately model low-frequency components for capturing precipitation patterns and high-frequency components for delineating sharply defined meteorological boundaries. Specifically, WaveC2R consists of two stages (i)Intensity-Boundary Decoupled Learning, which leverages wavelet decomposition and frequency-specific loss functions to separately optimize low-frequency intensity and high-frequency boundaries; and (ii)Detail-Enhanced
Diffusion Refinement, which employs frequency-aware conditional priors and multi-source data to progressively enhance fine-scale precipitation structures while preserving coarse-scale meteorological consistency. Experimental results on the publicly available SEVIR
dataset demonstrate that WaveC2R achieves state-of-the-art performance in satellite-based radar
retrieval, particularly excelling at preserving high-intensity precipitation features and sharply defined meteorological boundaries.
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All authors Chunlei Shi, Han Xu, Yinghao Li, Yi-Lin Wei, Yongchao Feng, Yecheng Zhang, Dan Niu
Image and Video Processing · Cross-listed from physics.ins-det
PlatonSPAD: A novel SPAD sensor for large-scale high-resolution particle detectors
Kodai Kaneyasu, Till Dieminger, Matthew Franks et al. (+3 more)
High-resolution 3D tracking with sub-nanosecond timing is required for the detection of elementary particles, such as
neutrinos. Conventional detectors, which utilize analog silicon photomultipliers, face challenges in balancing spatial resolution and scalability. To address this issue, a CMOS single-
photon avalanche diode (SPAD)-based high-resolution particle detector is being developed. This work presents a study on SPAD layout optimization and a 4x4 SPAD macropixel module, fabricated in 110 nm CIS technology. Measurement results confirm that high-fill-factor designs improve
photon detection efficiency without significant noise degradation. Furthermore, event-driven
photon mapping and time stamping, enabled by time-to-digital converters and dedicated pixel
circuits integrated into the 4x4 SPAD macropixel, were successfully demonstrated. This work is an essential step towards a sensor that detects probabilistic particle interactions and it lays the groundwork for the development of future large-scale SPAD-based particle detectors.
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All authors Kodai Kaneyasu, Till Dieminger, Matthew Franks, Davide Sgalaberna, Claudio Bruschini, Edoardo Charbon
Systems and Control
Deep reinforcement learning-based spacecraft attitude control with pointing keep-out constraint
Juntang Yang and Mohamed Khalil Ben-Larbi
This paper implements deep reinforcement learning (DRL) for spacecraft reorientation control with a single pointing keep-out zone. The Soft Actor-Critic (SAC)
algorithm is adopted to handle continuous state and action space. A new state representation is designed to explicitly include a compact representation of the attitude constraint zone. The reward function is formulated to achieve the control objective while enforcing the attitude constraint. A curriculum learning approach is used for the
agent training. Simulation results demonstrate the effectiveness of the proposed DRL-based method for spacecraft pointing-constrained attitude control.
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Systems and Control
A Deep Learning Density Shaping Model Predictive Gust Load Alleviation Control of a Compliant Wing Subjected to Atmospheric Turbulence
Seid H. Pourtakdoust and Amir H. Khodabakhsh
This study presents a novel deep learning approach aimed at enhancing
stochastic Gust Load Alleviation (GLA) specifically for compliant wings. The approach incorporates the concept of smooth wing camber variation, where the camber of the wing's chord is actively adjusted during flight using a control signal to achieve the desired aerodynamic loading. The proposed method employs a deep learning-based model predictive controller designed for probability density shaping. This controller effectively solves the probability density
evolution equation through a custom Physics-Informed Neural Network (PINN) and utilizes Automatic Differentiation for Model Predictive Control (MPC) optimization. Comprehensive numerical simulations were conducted on a compliant wing (CW) model, evaluating performance of the proposed approach against
stochastic gust profiles. The evaluation involved
stochastic aerodynamic loads generated from Band-Limited White Noise (BLWN) and Dryden gust models. The evaluation were conducted for two distinct Compliant Chord Fractions (CCF). The results demonstrate the effectiveness of the proposed probability density shaping model predictive control in alleviating
stochastic gust load and reducing wing tip deflection.
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Image and Video Processing · Cross-listed from cs.CV
Toward bilipshiz geometric models
Yonatan Sverdlov, Eitan Rosen and Nadav Dym
Many neural networks for point clouds are, by design, invariant to the
symmetries of this datatype: permutations and rigid motions. The purpose of this paper is to examine whether such networks preserve natural
symmetry aware distances on the point cloud spaces, through the notion of bi-Lipschitz equivalence. This inquiry is motivated by recent work in the Equivariant learning literature which highlights the advantages of bi-Lipschitz models in other scenarios. We consider two
symmetry aware metrics on point clouds: (a) The Procrustes Matching (PM) metric and (b) Hard Gromov Wasserstien distances. We show that these two distances themselves are not bi-Lipschitz equivalent, and as a corollary deduce that popular invariant networks for point clouds are not bi-Lipschitz with respect to the PM metric. We then show how these networks can be modified so that they do obtain bi-Lipschitz guarantees. Finally, we provide initial experiments showing the advantage of the proposed bi-Lipschitz model over standard invariant models, for the tasks of finding correspondences between 3D point clouds.
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Systems and Control · Cross-listed from cs.LG
Fast 3D Surrogate Modeling for Data Center Thermal Management
Soumyendu Sarkar, Antonio Guillen-Perez, Zachariah J Carmichael et al. (+6 more)
Reducing energy consumption and carbon emissions in data centers by enabling real-time temperature prediction is critical for sustainability and operational efficiency. Achieving this requires accurate modeling of the 3D temperature field to capture airflow dynamics and thermal interactions under varying operating conditions. Traditional thermal CFD solvers, while accurate, are computationally expensive and require expert-crafted meshes and boundary conditions, making them impractical for real-time use. To address these limitations, we develop a
vision-based surrogate modeling framework that operates directly on a 3D voxelized representation of the data center, incorporating server workloads, fan speeds, and HVAC temperature set points. We evaluate multiple architectures, including 3D CNN U-Net variants, a 3D
Fourier Neural Operator, and 3D
vision transformers, to map these thermal inputs to high-fidelity heat maps. Our results show that the surrogate models generalize across data center configurations and significantly speed up computations (20,000x), from hundreds of milliseconds to hours. This fast and accurate estimation of hot spots and temperature distribution enables real-time cooling control and workload redistribution, leading to substantial energy savings (7%) and reduced carbon footprint.
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All authors Soumyendu Sarkar, Antonio Guillen-Perez, Zachariah J Carmichael, Avisek Naug, Refik Mert Cam, Vineet Gundecha, Ashwin Ramesh Babu, Sahand Ghorbanpour, Ricardo Luna Gutierrez
Systems and Control
Adaptive Digital Twin of Sheet Metal Forming via Proper Orthogonal Decomposition-Based Koopman Operator with Model Predictive Control
Yi-Ping Chen, Derick Suarez, Ying-Kuan Tsai et al. (+6 more)
Digital Twin (DT) technologies are transforming manufacturing by enabling real-time prediction, monitoring, and control of complex processes. Yet, applying DT to deformation-based metal forming remains challenging because of the strongly coupled spatial-temporal behavior and the nonlinear relationship between toolpath and material response. For instance, sheet-metal forming by the English wheel, a highly flexible but artisan-dependent process, still lacks digital counterparts that can autonomously plan and adapt forming strategies. This study presents an adaptive DT framework that integrates Proper Orthogonal Decomposition (POD) for physics-aware dimensionality reduction with a Koopman operator for representing nonlinear system in a linear lifted space for the real-time decision-making via model predictive control (MPC). To accommodate evolving process conditions or material states, an online Recursive Least Squares (RLS)
algorithm is introduced to update the operator coefficients in real time, enabling continuous adaptation of the DT model as new deformation data become available. The proposed framework is experimentally demonstrated on a robotic English Wheel sheet metal forming system, where deformation fields are measured and modeled under varying toolpaths. Results show that the adaptive DT is capable of controlling the forming process to achieve the given target shape by effectively capturing non-stationary process behaviors. Beyond this case study, the proposed framework establishes a generalizable approach for interpretable, adaptive, and computationally-efficient DT of nonlinear manufacturing systems, bridging reduced-order physics representations with data-driven adaptability to support autonomous process control and optimization.
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All authors Yi-Ping Chen, Derick Suarez, Ying-Kuan Tsai, Vispi Karkaria, Guanzhong Hu, Zihan Chen, Ping Guo, Jian Cao, Wei Chen
Systems and Control
Tissue Activation Calculation in Dual-lead Deep Brain Stimulation
Anna Franziska Frigge and Alexander Medvedev
Deep
Brain Stimulation (DBS) is a well-established neurosurgical treatment aiming at symptom alleviation in a range of neurological and psychiatric diseases. Computational models of DBS are widely used to investigate the effects of stimulation on neural tissue, to explore stimulation targets and sweetspots, and ultimately, to aid clinicians in the DBS programming by calculating the stimulation parameters. Commonly, DBS is performed bilaterally, i.e. with one lead in each
brain hemisphere, where computational models are solved independently for one lead at a time. This paper treats scenarios where multiple DBS leads are implanted in close proximity to one another, resulting in interacting electrical fields and, therefore, potentially overlapping stimulation spreads. In particular, a global dual-lead model is compared to approximations derived from single-lead approaches in a cohort of twelve multiple sclerosis (MS) tremor patients. It is concluded that simple superposition of volumes of tissue activated (VTAs) underestimates activation, while superposition of electric fields or activating functions leads to overestimation. It is concluded that given close proximity of DBS leads, the VTA cannot be computed individually as stimulation fields exhibit significant and complex interaction. The approach is extended to modeling two obsessive compulsive disorder patients with medially placed leads, where similar VTA discrepancies as in the MS patient cohort are observed.
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Image and Video Processing
From Attention to Frequency: Integration of Vision Transformer and FFT-ReLU for Enhanced Image Deblurring
Syed Mumtahin Mahmud, Mahdi Mohd Hossain Noki, Prothito Shovon Majumder et al. (+3 more)
Image deblurring is vital in computer
vision, aiming to recover sharp images from blurry ones caused by motion or camera shake. While deep learning approaches such as CNNs and
Vision Transformers (ViTs) have advanced this field, they often struggle with complex or high-resolution blur and computational demands. We propose a new dual-domain architecture that unifies
Vision Transformers with a frequency-domain FFT-ReLU module, explicitly bridging spatial
attention modeling and frequency sparsity. In this structure, the ViT backbone captures local and global dependencies, while the FFT-ReLU component enforces frequency-domain sparsity to suppress blur-related artifacts and preserve fine details. Extensive experiments on
benchmark datasets demonstrate that this architecture achieves superior PSNR, SSIM, and perceptual quality compared to state-of-the-art models. Both quantitative metrics, qualitative comparisons, and human preference evaluations confirm its effectiveness, establishing a practical and generalizable paradigm for real-world image restoration.
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All authors Syed Mumtahin Mahmud, Mahdi Mohd Hossain Noki, Prothito Shovon Majumder, Abdul Mohaimen Al Radi, Md. Haider Ali, Md. Mosaddek Khan
Systems and Control
Semantic Property Maps for Driving Applications
Marcus Greiff, Ray Zhang, Takeru Shirasawa et al. (+1 more)
We consider the problem of estimating the parameters of a vehicle dynamics model for predictive control in driving applications. Instead of solely using the instantaneous parameters estimated from the vehicle signals, we combine this with cameras and update a probabilistic map with parameter estimates and semantic information using
Bayesian moment matching. Key to this approach is the map representation, which is constructed with conjugate priors to the measurement likelihoods and defined in the same path coordinates as the vehicle controller, such that the map can be externalized to provide a local representation of the parameter likelihoods that vary in space. The result is a spatial map of vehicle parameters adapted online to enhance the driving control system. We provide theoretical guarantees on the smoothness of relevant parameter likelihood statistics as a function of space, which is critical for their use in predictive control.
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All authors Marcus Greiff, Ray Zhang, Takeru Shirasawa, John Subosits
Audio and Speech Processing
Curved Worlds, Clear Boundaries: Generalizing Speech Deepfake Detection using Hyperbolic and Spherical Geometry Spaces
Farhan Sheth, Girish, Mohd Mujtaba Akhtar et al. (+1 more)
In this work, we address the challenge of generalizable audio deepfake detection (ADD) across diverse
speech synthesis paradigms-including conventional text-to-
speech (TTS) systems and modern
diffusion or flow-matching (FM) based generators. Prior work has mostly targeted individual synthesis families and often fails to generalize across paradigms due to overfitting to generation-specific artifacts. We hypothesize that synthetic
speech, irrespective of its generative origin, leaves behind shared structural distortions in the
embedding space that can be aligned through geometry-aware modeling. To this end, we propose RHYME, a unified detection framework that fuses utterance-level
embeddings from diverse pretrained
speech encoders using non-Euclidean projections. RHYME maps representations into
hyperbolic and spherical
manifolds-where
hyperbolic geometry excels at modeling hierarchical generator families, and spherical projections capture angular, energy-invariant cues such as periodic vocoder artifacts. The fused representation is obtained via Riemannian barycentric averaging, enabling synthesis-invariant
alignment. RHYME outperforms individual PTMs and homogeneous fusion baselines, achieving top performance and setting new state-of-the-art in cross-paradigm ADD.
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All authors Farhan Sheth, Girish, Mohd Mujtaba Akhtar, Muskaan Singh
Audio and Speech Processing
Towards Attribution of Generators and Emotional Manipulation in Cross-Lingual Synthetic Speech using Geometric Learning
Girish, Mohd Mujtaba Akhtar, Farhan Sheth et al. (+1 more)
In this work, we address the problem of finegrained traceback of emotional and manipulation characteristics from synthetically manipulated
speech. We hypothesize that combining semantic-prosodic cues captured by
Speech Foundation Models (SFMs) with fine-grained spectral dynamics from auditory representations can enable more precise tracing of both
emotion and manipulation source. To validate this hypothesis, we introduce MiCuNet, a novel multitask framework for fine-grained tracing of emotional and manipulation attributes in synthetically generated
speech. Our approach integrates SFM
embeddings with spectrogram-based auditory features through a mixed-
curvature projection mechanism that spans
Hyperbolic, Euclidean, and Spherical spaces guided by a learnable temporal gating mechanism. Our proposed method adopts a multitask learning setup to simultaneously predict original
emotions, manipulated
emotions, and manipulation sources on the EmoFake
dataset (EFD) across both English and Chinese subsets. MiCuNet yields consistent improvements, consistently surpassing conventional fusion strategies. To the best of our knowledge, this work presents the first study to explore a
curvature-adaptive framework specifically tailored for multitask tracking in synthetic
speech.
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All authors Girish, Mohd Mujtaba Akhtar, Farhan Sheth, Muskaan Singh
Systems and Control
Retail electricity costs and emissions incentives are misaligned for commercial and industrial power consumers
Fletcher T. Chapin, Akshay K. Rao, Adhithyan Sakthivelu et al. (+5 more)
Electrification is contributing to substantial growth in U.S. commercial and industrial loads, but the cost and Scope 2 carbon emission implications of this load growth are opaque for both power consumers and utilities. This work describes a unique spatiotemporally resolved data set of U.S. electricity costs and emissions and applies time series approximation methods to quantify the
alignment of electricity cost and emission incentives for large commercial and industrial consumers. We present a comprehensive spatiotemporal
dataset of U.S. price-based demand response (i.e., tariff) and incentive-based demand response programs, enabling direct comparison to previously published marginal emission factor, average emission factor, and day-ahead
market prices. We resolved the structural incompatibility and fragmentation of these
datasets by developing time series approximations of discrete data and unifying geospatially heterogeneous
datasets. Analysis of these
datasets reveals significant spatial and temporal heterogeneity in cost and carbon emissions incentives for demand-side energy flexibility, underscoring the importance of site selection as a key factor influencing power costs and Scope 2 emissions. Analysis also reveals broad misalignment of economic and emissions incentives under existing electricity tariff structures, meaning tariffs are incentivizing consumption of more carbon-intensive electricity, and highlighting potential barriers to electrification delivering carbon savings.
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All authors Fletcher T. Chapin, Akshay K. Rao, Adhithyan Sakthivelu, Carson I. Tucker, Eres David, Casey S. Chen, Erin Musabandesu, Meagan S. Mauter
Systems and Control
Privacy protection under the exposure of systems' prior information
Le Liu, Yu Kawano and Ming Cao
For systems whose states implicate sensitive information, their
privacy is of great concern. While notions like differential
privacy have been successfully introduced to dynamical systems, it is still unclear how a system's
privacy can be properly protected when facing the challenging yet frequently-encountered scenario where an adversary possesses prior knowledge, e.g., the steady state, of the system. This paper presents a new systematic approach to protect the
privacy of a discrete-time linear time-invariant system against adversaries knowledgeable of the system's prior information. We employ a tailored pointwise maximal leakage (PML)
privacy criterion. PML characterizes the worst-case
privacy performance, which is sharply different from that of the better-known mutual-information
privacy. We derive necessary and sufficient conditions for PML
privacy and construct tractable design procedures. Furthermore, our analysis leads to insight into how PML
privacy, differential
privacy, and mutual-information
privacy are related. We then revisit Kalman filters from the perspective of PML
privacy and derive a lower bound on the steady-state estimation-error covariance in terms of the PML parameters. Finally, the derived results are illustrated in a case study of
privacy protection for distributed sensing in smart buildings.
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Audio and Speech Processing
Direction-of-Arrival and Noise Covariance Matrix joint estimation for beamforming
Vitor Gelsleichter Probst Curtarelli, Stephan Paul and Anderson Wedderhoff Spengler
We propose a joint estimation method for the Direction-of-Arrival (DoA) and the Noise Covariance
Matrix (NCM) tailored for beamforming applications. Building upon an existing NCM framework, our approach simplifies the estimation procedure by deriving an quasi-linear solution, instead of the traditional exhaustive search. Additionally, we introduce a novel DoA estimation technique that operates across all frequency bins, improving robustness in reverberant environments. Simulation results demonstrate that our method outperforms classical techniques, such as MUSIC, in mid- to high-angle scenarios, achieving lower angular errors and superior signal enhancement through beamforming. The proposed framework was also fared against other techniques for signal enhancement, having better noise rejection and interference canceling capabilities. These improvements are validated using both theoretical and empirical performance metrics.
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Systems and Control · Cross-listed from cs.RO
Optimizing the flight path for a scouting Uncrewed Aerial Vehicle
Raghav Adhikari, Sachet Khatiwada and Suman Poudel
Post-disaster situations pose unique
navigation challenges. One of those challenges is the unstructured nature of the environment, which makes it hard to layout paths for rescue vehicles. We propose the use of Uncrewed Aerial Vehicle (
UAV) in such scenario to perform reconnaissance across the environment. To accomplish this, we propose an optimization-based approach to plan a path for the
UAV at optimal height where the sensors of the
UAV can cover the most area and collect data with minimum uncertainty.
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Systems and Control
Artifacts Are Not Noise: Embodied Resonance and the 70% Signal Loss in Conventional EEG
Ahmed Gamal Eldin
Current AI systems excel at pattern recognition but fail at causal
reasoning. We argue this is not an engineering limitation but reveals something fundamental about the nature of understanding itself. We propose that causal cognition requires a specific physical architecture:
stochastic, coupled oscillators with whole-system coordination. To test this, we analyzed high-density
EEG (64 channels, 10 subjects, 500 plus trials) from a P300 target recognition task. We computed the Kuramoto Order Parameter (R) to measure global phase synchronization and compared it to standard voltage (ERP) and coherence (ITC) metrics. Four findings establish the framework. Phase and voltage are globally independent (r of 0.048) yet strongly trial-coupled (r of 0.590), proving R captures hidden cognitive structure. Voltage precedes phase by 293 ms, revealing sequential computation. Frequency decomposition shows Theta (169 ms), Alpha (286 ms), and Beta (777 ms) cascade. Our metric is distinct from standard ITC (r of 0.155). Then we tested the standard assumption. Conventional artifact rejection removes eye movements, muscle activity, and autonomic signals before analysis. The standard model assumes cognition is neural activity plus noise. We ran the identical analysis with and without rejection. Removing artifacts reduced the trial-level correlation threefold (from 0.590 to 0.195). Target discrimination reversed sign (from positive 0.6 percent to negative 0.4 percent). What we discard as noise is 70 percent of the signal. This falsifies the standard model. Cognition is not isolated neural computation. It is whole-body phase synchronization spanning neural, muscular, and autonomic systems. For AI, the implications are direct:
embodied sensorimotor integration is not optional. It is the substrate that makes understanding possible.
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Systems and Control
Safe Planning in Interactive Environments via Iterative Policy Updates and Adversarially Robust Conformal Prediction
Omid Mirzaeedodangeh, Eliot Shekhtman, Nikolai Matni et al. (+1 more)
Safe planning of an autonomous
agent in interactive environments – such as the control of a self-driving vehicle among pedestrians – poses a major challenge as the behavior of the environment is unknown and reactive to the behavior of the autonomous
agent. This coupling gives rise to interaction-driven distribution shifts where the autonomous
agent's control policy may change the environment's behavior, thereby invalidating safety guarantees in existing work. Indeed, recent works have used conformal prediction (CP) to generate distribution-free safety guarantees using observed data of the environment. However, CP's assumption on data exchangeability is violated in interactive settings due to a circular dependency where a control policy update changes the environment's behavior, and vice versa. To address this gap, we propose an iterative framework that robustly maintains safety guarantees across policy updates by quantifying the potential impact of a planned policy update on the environment's behavior. We realize this via adversarially robust CP where we perform a regular CP step in each episode using observed data under the current policy, but then transfer safety guarantees across policy updates by analytically adjusting the CP result to account for distribution shifts. This adjustment is performed based on a policy-to-trajectory sensitivity analysis, resulting in a safe, episodic open-loop planner. We further conduct a contraction analysis of the system providing conditions under which both the CP results and the policy updates are guaranteed to converge. We empirically demonstrate these safety and convergence guarantees on a two-dimensional car-pedestrian and a high-dimensional quadcopter case study. To the best of our knowledge, these are the first results that provide valid safety guarantees in such interactive settings.
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All authors Omid Mirzaeedodangeh, Eliot Shekhtman, Nikolai Matni, Lars Lindemann
Systems and Control · Cross-listed from cs.LG
Differentiable Filtering for Learning Hidden Markov Models
Reginald Zhiyan Chen, Heng-Sheng Chang and Prashant G. Mehta
Hidden Markov Models (HMMs) are fundamental for modeling sequential data, yet learning their parameters from observations remains challenging. Classical methods like the Baum-Welch
algorithm are computationally intensive and prone to local optima, while modern spectral
algorithms offer provable guarantees but may produce probability outputs outside valid ranges. This work introduces Belief Net, a differentiable filtering framework that learns HMM parameters by formulating the forward filter as a structured neural network and optimizing it with
stochastic gradient descent. This architecture recursively updates the belief state, which represents the posterior probability distribution over hidden states based on the observation history. Unlike black-box
transformer models, Belief Net's learnable weights are explicitly the logits of the initial distribution, transition
matrix, and emission
matrix, ensuring full interpretability. The model processes observation sequences using a decoder-only (causal) architecture and is trained end-to-end with standard autoregressive next-observation prediction loss. On synthetic HMM data, Belief Net achieves faster convergence than Baum-Welch while successfully recovering parameters in both undercomplete and overcomplete settings, whereas spectral methods prove ineffective in the latter. Comparisons with
transformer-based models are also presented on real-world
language data.
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