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Dynamic Leader-Follower Consensus with Adversaries: A Multi-Hop Relay Approach

Yuan, Liwei, Ishii, Hideaki

arXiv.org Artificial Intelligence

Within this area, resilient consensus problems have gained substantial attention across the disciplines of systems control, distributed computing, and robotics (Vaidya et al. (2012); Sundaram and Gharesifard (2018); Yu et al. (2022)). Here, the objective for the nonfaulty, normal agents is to reach consensus despite misbehaviors of adversarial agents. Existing resilient consensus algorithms are designed to ensure that normal agents reach consensus on a value within the convex hull of their initial states, e.g., Yuan and Ishii (2021, 2023); Yu et al. (2022). Meanwhile, numerous formation control and reliable broadcast problems require agents to reach consensus on a predetermined reference value, which may lie inside or outside that convex hull (Bullo et al. This work was supported in part by the National Natural Science Foundation of China under Grant 62403188 and in part by JSPS under Grants-in-Aid for Scientific Research Grant No. 22H01508 and 24K00844. The material in this paper was not presented at any conference.


Homotopy Smoothing for Non-Smooth Problems with Lower Complexity than O(1/\epsilon)

Neural Information Processing Systems

In this paper, we develop a novel {\bf ho}moto{\bf p}y {\bf s}moothing (HOPS) algorithm for solving a family of non-smooth problems that is composed of a non-smooth term with an explicit max-structure and a smooth term or a simple non-smooth term whose proximal mapping is easy to compute. The best known iteration complexity for solving such non-smooth optimization problems is $O(1/\epsilon)$ without any assumption on the strong convexity. In this work, we will show that the proposed HOPS achieved a lower iteration complexity of $\tilde O(1/\epsilon^{1-\theta})$ with $\theta\in(0,1]$ capturing the local sharpness of the objective function around the optimal solutions. To the best of our knowledge, this is the lowest iteration complexity achieved so far for the considered non-smooth optimization problems without strong convexity assumption. The HOPS algorithm employs Nesterov's smoothing technique and Nesterov's accelerated gradient method and runs in stages, which gradually decreases the smoothing parameter in a stage-wise manner until it yields a sufficiently good approximation of the original function. We show that HOPS enjoys a linear convergence for many well-known non-smooth problems (e.g., empirical risk minimization with a piece-wise linear loss function and $\ell_1$ norm regularizer, finding a point in a polyhedron, cone programming, etc). Experimental results verify the effectiveness of HOPS in comparison with Nesterov's smoothing algorithm and the primal-dual style of first-order methods.



Appendices for Baleen A Data Details

Neural Information Processing Systems

Table 6: Sizes of the splits of the datasets used in this work. It contains approximately 5M passages (1.5 GiB uncompressed). We implement Baleen using Python 3.7 and PyTorch 1.6 and rely extensively on the HuggingFace We train and test with automatic mixed precision that is built into PyTorch. To train the single-hop retriever used to initiate the supervision procedure of 3.2, we follow the training strategy of Khattab et al. ColBERT model to create training triples, and then we train our retriever (in this case, FLIPR for first-hop) with these triples.



Adaptive Cooperative Transmission Design for Ultra-Reliable Low-Latency Communications via Deep Reinforcement Learning

Yu, Hyemin, Yang, Hong-Chuan

arXiv.org Artificial Intelligence

Next-generation wireless communication systems must support ultra-reliable low-latency communication (URLLC) service for mission-critical applications. Meeting stringent URLLC requirements is challenging, especially for two-hop cooperative communication. In this paper, we develop an adaptive transmission design for a two-hop relaying communication system. Each hop transmission adaptively configures its transmission parameters separately, including numerology, mini-slot size, and modulation and coding scheme, for reliable packet transmission within a strict latency constraint. We formulate the hop-specific transceiver configuration as a Markov decision process (MDP) and propose a dual-agent reinforcement learning-based cooperative latency-aware transmission (DRL-CoLA) algorithm to learn latency-aware transmission policies in a distributed manner. Simulation results verify that the proposed algorithm achieves the near-optimal reliability while satisfying strict latency requirements.



Universal Dynamics with Globally Controlled Analog Quantum Simulators

Hu, Hong-Ye, Gomez, Abigail McClain, Chen, Liyuan, Trowbridge, Aaron, Goldschmidt, Andy J., Manchester, Zachary, Chong, Frederic T., Jaffe, Arthur, Yelin, Susanne F.

arXiv.org Artificial Intelligence

Analog quantum simulators with global control fields have emerged as powerful platforms for exploring complex quantum phenomena. Recent breakthroughs, such as the coherent control of thousands of atoms, highlight the growing potential for quantum applications at scale. Despite these advances, a fundamental theoretical question remains unresolved: to what extent can such systems realize universal quantum dynamics under global control? Here we establish a necessary and sufficient condition for universal quantum computation using only global pulse control, proving that a broad class of analog quantum simulators is, in fact, universal. We further extend this framework to fermionic and bosonic systems, including modern platforms such as ultracold atoms in optical superlattices. Crucially, to connect the theoretical possibility with experimental reality, we introduce a new control technique into the experiment - direct quantum optimal control. This method enables the synthesis of complex effective Hamiltonians and allows us to incorporate realistic hardware constraints. To show its practical power, we experimentally engineer three-body interactions outside the blockade regime and demonstrate topological dynamics on a Rydberg atom array. Using the new control framework, we overcome key experimental challenges, including hardware limitations and atom position fluctuations in the non-blockade regime, by identifying smooth, short-duration pulses that achieve high-fidelity dynamics. Experimental measurements reveal dynamical signatures of symmetry-protected-topological edge modes, confirming both the expressivity and feasibility of our approach. Our work opens a new avenue for quantum simulation beyond native hardware Hamiltonians, enabling the engineering of effective multi-body interactions and advancing the frontier of quantum information processing with globally-controlled analog platforms.


A Fano-Style Accuracy Upper Bound for LLM Single-Pass Reasoning in Multi-Hop QA

Wan, Kaiyang, Gao, Lang, Mu, Honglin, Nakov, Preslav, Wang, Yuxia, Chen, Xiuying

arXiv.org Artificial Intelligence

Multi-Hop Question Answering (MHQA) requires integrating dispersed, interdependent evidence through sequential reasoning under noise. This task is challenging for LLMs as they have a finite per-pass output capacity, beyond which the integration of task-relevant evidence proves unreliable. Consequently, the single-pass reasoning paradigm is inherently vulnerable to this capacity overflow. To formalize this bottleneck, our analysis establishes a Fano-style accuracy upper bound, defining a theoretical performance ceiling for single-pass LLMs. This bound reveals that accuracy inevitably collapses once task complexity exceeds model capacity, providing general principles for capacity-aware representation and structuring of MHQA in LLMs. Building on these principles, we introduce a proof-of-concept multi-call framework for MHQA, InfoQA. It ensures high per-step accuracy by combining capacity-aware task decomposition with active pruning of prior reasoning traces, keeping the information load within the single-pass limit. It further achieves robustness by a dependency-explicit workflow that enables precise control over the reasoning path. We construct a stringent and noise-rich benchmark to validate our theory and framework. Experimental results show that model behavior aligns with our predicted capacity curves while InfoQA achieves consistent performance improvements. We hope our work inspires more LLM multi-step reasoning methods: \faGithub \href{https://github.com/KaiyangWan/InfoQA}{InfoQA}.


Appendices for Baleen A Data Details

Neural Information Processing Systems

Table 6: Sizes of the splits of the datasets used in this work. It contains approximately 5M passages (1.5 GiB uncompressed). We implement Baleen using Python 3.7 and PyTorch 1.6 and rely extensively on the HuggingFace We train and test with automatic mixed precision that is built into PyTorch. To train the single-hop retriever used to initiate the supervision procedure of 3.2, we follow the training strategy of Khattab et al. ColBERT model to create training triples, and then we train our retriever (in this case, FLIPR for first-hop) with these triples.