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 okumura


db-LaCAM: Fast and Scalable Multi-Robot Kinodynamic Motion Planning with Discontinuity-Bounded Search and Lightweight MAPF

Moldagalieva, Akmaral, Okumura, Keisuke, Prorok, Amanda, Hönig, Wolfgang

arXiv.org Artificial Intelligence

State-of-the-art multi-robot kinodynamic motion planners struggle to handle more than a few robots due to high computational burden, which limits their scalability and results in slow planning time. In this work, we combine the scalability and speed of modern multi-agent path finding (MAPF) algorithms with the dynamic-awareness of kinodynamic planners to address these limitations. To this end, we propose discontinuity-Bounded LaCAM (db-LaCAM), a planner that utilizes a precomputed set of motion primitives that respect robot dynamics to generate horizon-length motion sequences, while allowing a user-defined discontinuity between successive motions. The planner db-LaCAM is resolution-complete with respect to motion primitives and supports arbitrary robot dynamics. Extensive experiments demonstrate that db-LaCAM scales efficiently to scenarios with up to 50 robots, achieving up to ten times faster runtime compared to state-of-the-art planners, while maintaining comparable solution quality. The approach is validated in both 2D and 3D environments with dynamics such as the unicycle and 3D double integrator. We demonstrate the safe execution of trajectories planned with db-LaCAM in two distinct physical experiments involving teams of flying robots and car-with-trailer robots.


Graph Attention-Guided Search for Dense Multi-Agent Pathfinding

Jain, Rishabh, Okumura, Keisuke, Amir, Michael, Prorok, Amanda

arXiv.org Artificial Intelligence

Finding near-optimal solutions for dense multi-agent pathfinding (MAPF) problems in real-time remains challenging even for state-of-the-art planners. To this end, we develop a hybrid framework that integrates a learned heuristic derived from MAGAT, a neural MAPF policy with a graph attention scheme, into a leading search-based algorithm, LaCAM. While prior work has explored learning-guided search in MAPF, such methods have historically underperformed. In contrast, our approach, termed LaGAT, outperforms both purely search-based and purely learning-based methods in dense scenarios. This is achieved through an enhanced MAGAT architecture, a pre-train-then-fine-tune strategy on maps of interest, and a deadlock detection scheme to account for imperfect neural guidance. Our results demonstrate that, when carefully designed, hybrid search offers a powerful solution for tightly coupled, challenging multi-agent coordination problems.


Pathfinding with Lazy Successor Generation

Okumura, Keisuke

arXiv.org Artificial Intelligence

We study a pathfinding problem where only locations (i.e., vertices) are given, and edges are implicitly defined by an oracle answering the connectivity of two locations. Despite its simple structure, this problem becomes non-trivial with a massive number of locations, due to posing a huge branching factor for search algorithms. Limiting the number of successors, such as with nearest neighbors, can reduce search efforts but compromises completeness. Instead, we propose a novel LaCAS* algorithm, which does not generate successors all at once but gradually generates successors as the search progresses. This scheme is implemented with k-nearest neighbors search on a k-d tree. LaCAS* is a complete and anytime algorithm that eventually converges to the optima. Extensive evaluations demonstrate the efficacy of LaCAS*, e.g., solving complex pathfinding instances quickly, where conventional methods falter.


InstructCMP: Length Control in Sentence Compression through Instruction-based Large Language Models

Juseon-Do, null, Kwon, Jingun, Kamigaito, Hidetaka, Okumura, Manabu

arXiv.org Artificial Intelligence

Extractive summarization can produce faithful summaries but often requires additional constraints such as a desired summary length. Traditional sentence compression models do not typically consider the constraints because of their restricted model abilities, which require model modifications for coping with them. To bridge this gap, we propose Instruction-based Compression (InstructCMP), an approach to the sentence compression task that can consider the length constraint through instructions by leveraging the zero-shot task-solving abilities of Large Language Models (LLMs). For this purpose, we created new evaluation datasets by transforming traditional sentence compression datasets into an instruction format. By using the datasets, we first reveal that the current LLMs still face challenges in accurately controlling the length for a compressed text. To address this issue, we propose an approach named "length priming," that incorporates additional length information into the instructions without external resources. While the length priming effectively works in a zero-shot setting, a training dataset with the instructions would further improve the ability of length control. Thus, we additionally created a training dataset in an instruction format to fine-tune the model on it. Experimental results and analysis show that applying the length priming significantly improves performances of InstructCMP in both zero-shot and fine-tuning settings without the need of any model modifications.


Improving LaCAM for Scalable Eventually Optimal Multi-Agent Pathfinding

Okumura, Keisuke

arXiv.org Artificial Intelligence

This study extends the recently-developed LaCAM algorithm for multi-agent pathfinding (MAPF). LaCAM is a sub-optimal search-based algorithm that uses lazy successor generation to dramatically reduce the planning effort. We present two enhancements. First, we propose its anytime version, called LaCAM*, which eventually converges to optima, provided that solution costs are accumulated transition costs. Second, we improve the successor generation to quickly obtain initial solutions. Exhaustive experiments demonstrate their utility. For instance, LaCAM* sub-optimally solved 99% of the instances retrieved from the MAPF benchmark, where the number of agents varied up to a thousand, within ten seconds on a standard desktop PC, while ensuring eventual convergence to optima; developing a new horizon of MAPF algorithms.


La veille de la cybersécurité

#artificialintelligence

Artificial intelligence and cutting-edge data analysis software mean that underwriters can now make predictions about the weather, natural disasters and senile dementia that previously "only god knew about", the president of one of Japan's biggest insurance companies has claimed. The bold assertion by Mikio Okumura, head of Sompo Holdings, comes as the company prepares to roll out Japan's first dementia prevention insurance package -- a product designed for the world's oldest society and based on analysis of the heartbeats, appetite and sleeping patterns of thousands of nursing home residents. The move by Sompo marks the latest insurance industry escalation of a battle to secure an advantage through tech. Okumura said this was an area of competition that would decide the survivability of individual companies as they moved away from their conventional business areas. The "god" claim follows Sompo's $500mn investment two years ago in Palantir, the US specialist in big data analysis, and its taking of a 22 per cent stake in a Japanese AI start-up, Abeja.


Who scams the scammers? Meet the scambaiters

The Guardian

For the past two years, the LA-based voice actor has run a sort of reverse call centre, deliberately ringing the people most of us hang up on – scammers who pose as tax agencies or tech-support companies or inform you that you've recently been in a car accident you somehow don't recall. When Okumura gets a scammer on the line, she will pretend to be an old lady, or a six-year-old girl, or do an uncanny impression of Apple's virtual assistant Siri. Once, she successfully fooled a fake customer service representative into believing that she was Britney Spears. "I waste their time," she explains, "and now they're not stealing from someone's grandma." Okumura is a "scambaiter" – a type of vigilante who disrupts, exposes or even scams the world's scammers.