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The Multi-agent Path Finding (MAPF) problem consists in all agents having to move to their own destinations while avoiding collisions. In practical applications to the problem, such as for navigation in an automated warehouse, MAPF must be solved iteratively. We present here a novel approach to iterative MAPF, that we call Priority Inheritance with Backtracking (PIBT). PIBT gives a unique priority to each agent every timestep, so that all movements are prioritized. Priority inheritance, which aims at dealing effectively with priority inversion in path adjustment within a small time window, can be applied iteratively and a backtracking protocol prevents agents from being stuck. We prove that, regardless of their number, all agents are guaranteed to reach their destination within finite time, when the environment is a graph such that all pairs of adjacent nodes belong to a simple cycle of length 3 or more (e.g., biconnected). Our implementation of PIBT can be fully decentralized without global communication. Experimental results over various scenarios confirm that PIBT is adequate both for finding paths in large environments with many agents, as well as for conveying packages in an automated warehouse.

We present the Kilogrid, an open-source virtualization environment and data logging manager for the Kilobot robot, Kilobot for short. The Kilogrid has been designed to extend the sensory-motor abilities of the Kilobot, to simplify the task of collecting data during experiments, and to provide researchers with a tool to fine-control the experimental setup and its parameters. Based on the design of the Kilobot and compatible with existing hardware, the Kilogrid is a modular system composed of a grid of computing nodes, or modules, that provides a bidirectional communication channel between the Kilobots and a remote workstation. In this paper, we describe the hardware and software architecture of the Kilogrid system as well as its functioning to accompany its release as a new open-hardware tool for the swarm robotics community. We demonstrate the capabilities of the Kilogrid using a 200-module Kilogrid, swarms of up to 100 Kilobots, and four different case studies: exploration and obstacle avoidance, site selection based on multiple gradients, plant watering, and pheromone-based foraging. Through this set of case studies, we

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AlCl 3 catalyzes addition reactions of hydrooligosilanes (H(SiMe 2 ) n R; n = 2-4, R = H, Me, Ph) with 1-decyne and other alkynes under mild conditions. In most reactions the Si-Si bonds remain intact to form anticipated products in fair to excellent yields, although Si-Ph bonds appear to be cleaved partially under the conditions. Arylethynes tend to form abnormal products due to Si-Si bond scission, but at a low temperature, the addition reaction proceeds normally. The reaction of 1,2-dihydrotetramethyldisilane with 1-decyne furnishes 1,2-didecenyldisilane, 1,3-didecenyltrisilane, and other byproducts at 0 °C, while the reaction run at a lower temperature proceeds cleanly. 1,3-Dihydrohexamethyltrisilane reacts more cleanly even at 0 °C. The reaction of pentamethyldisilane with 1,6-heptadiyne proceeds in a different direction, leading to cyclization. 1,7-Octadiyne reacts with 1,3-dihydrohexamethyltrisilane to give a polymeric material. The reaction of 1,2,3-trihydropentamethyltrisilane or poly(phenylsilylene) with 1-dectyne proceeds cleanly without perceptible Si-Si bond cleavage. IntroductionHydrosilylation is a long-known reaction and is an indispensable tool to create a silicon-to-carbon bond. 1 The majority of precedents deal with reactions with hydromonosilanes such as trichlorosilane, phenyldimethylsilane, trimethoxysilane, and diphenylsilane. As far as transition metal-catalyzed hydrosilylation is concerned, the reaction with a hydrooligosilane, H(SiMe 2 ) n R, has been believed to be a rather tough and intricate task due to the Si-Si bond cleavage, 2 although very few successful examples have been encountered incidentally. 3 For instance, Urenovitch and West reported long ago that attempted platinum-catalyzed reaction of 1-octene with pentamethyldisilane gave trimethylsilane and a trace of octyltrimethylsilane. 4 Besides transition metal complexes, Lewis acids are also known to catalyze the hydrosilylation with hydromonosilanes. 5 Rosenberg and co-workers have reported Lewis acid-catalyzed reactions of thiobenzophenone, thiols, phenols, thiophenols, aldehydes, and R-diketones with hydrodisilanes. 6 However, Lewis acid-catalyzed reactions of hydrooligo-and hydropolysilanes with unsaturated carbon linkages have not been documented. 7 This article discloses that AlCl 3 is a capable catalyst to promote the addition of hydrooligosilanes and hydropolysilanes to alkynes without deterioration of the silicon chain under carefully tuned conditions. A possible side reaction, which we have to keep in mind beforehand, is skeletal rearrangement of Si-Si chains. 8 In the present study, such a † Part of the Dietmar Seyferth Festschrift.