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 Learning Graphical Models


(SP)$^2$-Net: A Neural Spatial Spectrum Method for DOA Estimation

arXiv.org Machine Learning

We consider the problem of estimating the directions of arrival (DOAs) of multiple sources from a single snapshot of an antenna array, a task with many practical applications. In such settings, the classical Bartlett beamformer is commonly used, as maximum likelihood estimation becomes impractical when the number of sources is unknown or large, and spectral methods based on the sample covariance are not applicable due to the lack of multiple snapshots. However, the accuracy and resolution of the Bartlett beamformer are fundamentally limited by the array aperture. In this paper, we propose a deep learning technique, comprising a novel architecture and training strategy, for generating a high-resolution spatial spectrum from a single snapshot. Specifically, we train a deep neural network that takes the measurements and a hypothesis angle as input and learns to output a score consistent with the capabilities of a much wider array. At inference time, a heatmap can be produced by scanning an arbitrary set of angles. We demonstrate the advantages of our trained model, named (SP)$^2$-Net, over the Bartlett beamformer and sparsity-based DOA estimation methods.


Accelerating Atomic Fine Structure Determination with Graph Reinforcement Learning

arXiv.org Artificial Intelligence

Atomic data determined by analysis of observed atomic spectra are essential for plasma diagnostics. For each low-ionisation open d- and f-subshell atomic species, around $10^3$ fine structure level energies can be determined through years of analysis of $10^4$ observable spectral lines. We propose the automation of this task by casting the analysis procedure as a Markov decision process and solving it by graph reinforcement learning using reward functions learned on historical human decisions. In our evaluations on existing spectral line lists and theoretical calculations for Co II and Nd II-III, hundreds of level energies were computed within hours, agreeing with published values in 95% of cases for Co II and 54-87% for Nd II-III. As the current efficiency in atomic fine structure determination struggles to meet growing atomic data demands from astronomy and fusion science, our new artificial intelligence approach sets the stage for closing this gap.


Automated Cyber Defense with Generalizable Graph-based Reinforcement Learning Agents

arXiv.org Artificial Intelligence

Deep reinforcement learning (RL) is emerging as a viable strategy for automated cyber defense (ACD). The traditional RL approach represents networks as a list of computers in various states of safety or threat. Unfortunately, these models are forced to overfit to specific network topologies, rendering them ineffective when faced with even small environmental perturbations. In this work, we frame ACD as a two-player context-based partially observable Markov decision problem with observations represented as attributed graphs. This approach allows our agents to reason through the lens of relational inductive bias. Agents learn how to reason about hosts interacting with other system entities in a more general manner, and their actions are understood as edits to the graph representing the environment. By introducing this bias, we will show that our agents can better reason about the states of networks and zero-shot adapt to new ones. We show that this approach outperforms the state-of-the-art by a wide margin, and makes our agents capable of defending never-before-seen networks against a wide range of adversaries in a variety of complex, and multi-agent environments.


Quantum Reinforcement Learning with Dynamic-Circuit Qubit Reuse and Grover-Based Trajectory Optimization

arXiv.org Artificial Intelligence

A fully quantum reinforcement learning framework is developed that integrates a quantum Markov decision process, dynamic circuit-based qubit reuse, and Grover's algorithm for trajectory optimization. The framework encodes states, actions, rewards, and transitions entirely within the quantum domain, enabling parallel exploration of state-action sequences through superposition and eliminating classical subroutines. Dynamic circuit operations, including mid-circuit measurement and reset, allow reuse of the same physical qubits across multiple agent-environment interactions, reducing qubit requirements from 7*T to 7 for T time steps while preserving logical continuity. Quantum arithmetic computes trajectory returns, and Grover's search is applied to the superposition of these evaluated trajectories to amplify the probability of measuring those with the highest return, thereby accelerating the identification of the optimal policy. Simulations demonstrate that the dynamic-circuit-based implementation preserves trajectory fidelity while reducing qubit usage by 66 percent relative to the static design. Experimental deployment on IBM Heron-class quantum hardware confirms that the framework operates within the constraints of current quantum processors and validates the feasibility of fully quantum multi-step reinforcement learning under noisy intermediate-scale quantum conditions. This framework advances the scalability and practical application of quantum reinforcement learning for large-scale sequential decision-making tasks.


FloorSAM: SAM-Guided Floorplan Reconstruction with Semantic-Geometric Fusion

arXiv.org Artificial Intelligence

Abstract--Reconstructing building floor plans from point cloud data is a critical technology for indoor navigation, building information modeling (BIM), and highly accurate precise indoor measurement applications. Traditional methods, such as geometric algorithms and Mask R-CNN-based deep learning for mask segmentation, often suffer from sensitivity to noise, limited generalization, and loss of geometric details, severely impacting measurement accuracy. This study proposes an innovative framework, FloorSAM, that integrates room-height point cloud density maps with the guided segmentation capabilities of the Segment Anything Model (SAM) to enhance the precision of floor plan reconstruction from LiDAR point cloud data. By applying grid-based filtering to retain elevation point clouds near the ceiling of each region, combined with adaptive resolution projection and image enhancement techniques, a top-down density map is generated, improving the robustness and accuracy of spatial feature measurement. This framework leverages SAM's zero-shot learning to achieve high-fidelity room segmentation, remarkably enhancing reconstruction and measurement accuracy across diverse building layouts. Subsequently, leveraging SAM's zero-shot guided segmentation capabilities, high-quality room masks are generated based on adaptive prompt points, followed by a multistage filtering process to extract precise semantic masks for individual rooms. Through joint analysis of mask and point cloud modalities, contour extraction and regularization are performed, integrating semantic segmentation with geometric information to produce accurate room floor plans and recover topological relationships between rooms.


Nonconvex Regularization for Feature Selection in Reinforcement Learning

arXiv.org Artificial Intelligence

The primary objective of RL is for an agent to learn an optimal policy to control a system by minimizing a long-term loss, represented by the Q-function. This learning occurs through interactions with the environment, which is typically modeled as a Markov decision process (MDP). In most high-dimensional, real-world problems, explicitly representing the Q-function for all possible states and actions is impractical due to the "curse of dimensionality." A common solution is to approximate the Q-function using a parametric (functional) representation. This, however, introduces a fundamental trade-off between approximation accuracy and computational complexity: reducing the approximation error generally requires a large number of features in the parametric model, which in turn increases computational demands. Feature selection, achieved via a sparse representation over a large basis of functions, is an effective way to alleviate this tradeoff, mitigate overfitting, and improve sample efficiency.


Distribution Estimation for Global Data Association via Approximate Bayesian Inference

arXiv.org Artificial Intelligence

Abstract-- Global data association is an essential prerequisite for robot operation in environments seen at different times or by different robots. Repetitive or symmetric data creates significant challenges for existing methods, which typically rely on maximum likelihood estimation or maximum consensus to produce a single set of associations. However, in ambiguous scenarios, the distribution of solutions to global data association problems is often highly multimodal, and such single-solution approaches frequently fail. In this work, we introduce a data association framework that leverages approximate Bayesian inference to capture multiple solution modes to the data association problem, thereby avoiding premature commitment to a single solution under ambiguity. Our approach represents hypothetical solutions as particles that evolve according to a deterministic or randomized update rule to cover the modes of the underlying solution distribution. Furthermore, we show that our method can incorporate optimization constraints imposed by the data association formulation and directly benefit from GPU-parallelized optimization. Extensive simulated and real-world experiments with highly ambiguous data show that our method correctly estimates the distribution over transformations when registering point clouds or object maps. I. INTRODUCTION Data association is essential in many robotic applications, enabling key perception technologies such as dynamic object tracking [1]-[3] and simultaneous localization and mapping (SLAM) [4]-[6]. In these scenarios, robots must recognize when an object or feature they are currently observing is the same as something they (or another robot) may have seen from a different perspective. Without correct data association, the environment representation may be inconsistent, leading to undesirable behaviors in downstream tasks (e.g., incorrect associations in loop closure detection can lead to dramatically distorted maps [6]).


Universal Learning of Stochastic Dynamics for Exact Belief Propagation using Bernstein Normalizing Flows

arXiv.org Artificial Intelligence

Predicting the distribution of future states in a stochastic system, known as belief propagation, is fundamental to reasoning under uncertainty. However, nonlinear dynamics often make analytical belief propagation intractable, requiring approximate methods. When the system model is unknown and must be learned from data, a key question arises: can we learn a model that (i) universally approximates general nonlinear stochastic dynamics, and (ii) supports analytical belief propagation? This paper establishes the theoretical foundations for a class of models that satisfy both properties. The proposed approach combines the expressiveness of normalizing flows for density estimation with the analytical tractability of Bernstein polynomials. Empirical results show the efficacy of our learned model over state-of-the-art data-driven methods for belief propagation, especially for highly non-linear systems with non-additive, non-Gaussian noise.


Fully Decentralized Cooperative Multi-Agent Reinforcement Learning is A Context Modeling Problem

arXiv.org Artificial Intelligence

This paper studies fully decentralized cooperative multi-agent reinforcement learning, where each agent solely observes the states, its local actions, and the shared rewards. The inability to access other agents' actions often leads to non-stationarity during value function updates and relative overgeneralization during value function estimation, hindering effective cooperative policy learning. However, existing works fail to address both issues simultaneously, due to their inability to model the joint policy of other agents in a fully decentralized setting. To overcome this limitation, we propose a novel method named Dynamics-A ware Context (DAC), which formalizes the task, as locally perceived by each agent, as an Contextual Markov Decision Process, and further addresses both non-stationarity and relative overgeneralization through dynamics-aware context modeling. Specifically, DAC attributes the non-stationary local task dynamics of each agent to switches between unobserved contexts, each corresponding to a distinct joint policy. Then, DAC models the step-wise dynamics distribution using latent variables and refers to them as contexts. For each agent, DAC introduces a context-based value function to address the non-stationarity issue during value function update. For value function estimation, an optimistic marginal value is derived to promote the selection of cooperative actions, thereby addressing the relative overgeneralization issue. Experimentally, we evaluate DAC on various cooperative tasks (including matrix game, predator and prey, and SMAC), and its superior performance against multiple baselines validates its effectiveness.


Trust-Aware Embodied Bayesian Persuasion for Mixed-Autonomy

arXiv.org Artificial Intelligence

Safe and efficient interaction between autonomous vehicles (AVs) and human-driven vehicles (HVs) is a critical challenge for future transportation systems. While game-theoretic models capture how AVs influence HVs, they often suffer from a long-term decay of influence and can be perceived as manipulative, eroding the human's trust. This can paradoxically lead to riskier human driving behavior over repeated interactions. In this paper, we address this challenge by proposing the Trust-Aware Embodied Bayesian Persuasion (TA-EBP) framework. Our work makes three key contributions: First, we apply Bayesian persuasion to model communication at traffic intersections, offering a transparent alternative to traditional game-theoretic models. Second, we introduce a trust parameter to the persuasion framework, deriving a theorem for the minimum trust level required for influence. Finally, we ground the abstract signals of Bayesian persuasion theory into a continuous, physically meaningful action space, deriving a second theorem for the optimal signal magnitude, realized as an AV's forward nudge. Additionally, we validate our framework in a mixed-autonomy traffic simulation, demonstrating that TA-EBP successfully persuades HVs to drive more cautiously, eliminating collisions and improving traffic flow compared to baselines that either ignore trust or lack communication. Our work provides a transparent and non-strategic framework for influence in human-robot interaction, enhancing both safety and efficiency.