Abstract
We consider the Embedded Pattern Formation (epf) problem introduced in Fujinaga et al. (SIAM J Comput 44(3):740–785, 2015). Given a set F of distinct points in the Euclidean plane (called here fixed-points) and a set R of robots such that \(|R|=|F|\), the problem asks for a distributed algorithm that moves robots so as to occupy all points in F. Initially, each robot occupies a distinct position. When active, a robot operates in standard Look-Compute-Move cycles. In one cycle, a robot perceives the current configuration in terms of the robots’ positions and the fixed-points (Look) according to its own coordinate system, decides whether to move toward some direction (Compute), and in the positive case it moves (Move). Cycles are performed asynchronously for each robot. Robots are oblivious, anonymous, silent and execute the same deterministic algorithm. In the mentioned paper, the problem has been investigated by endowing robots with chirality, that is they share a common left-right orientation. Here we consider epf without chirality, and we fully characterize when it can be solved by designing a deterministic distributed algorithm that works for all configurations but those identified as unsolvable. The algorithm has been designed according to a rigorous approach, characterized by the use of logical predicates associated to each move used by the robots. This induces a greater level of detail that provides us rigorous bases to state the correctness of the algorithm.
Similar content being viewed by others
Notes
We can assume \(t_i = i\) for all \(i = 0,1,\ldots \) since the information relevant in the definition of execution is the order in which the different snapshots occur and not the exact time in which each snapshots is taken.
Here the term ‘phase’ is informally used to denote a generic part of an algorithm and hence it is not referred to the definition of phase provided in Sect. 2.
By Corollary 2, axes with only fixed-points cannot exist as the initial configuration was solvable and the moves performed from the initial configuration until the current step guarantee to not create such kind of axes.
\(\sphericalangle (\ell _1,\ell _2)\) is the smallest angle defined by the half-lines \(\ell _1\) and \(\ell _2\).
References
Agmon, N., Peleg, D.: Fault-tolerant gathering algorithms for autonomous mobile robots. SIAM J. Comput. 36(1), 56–82 (2006)
Bérard, B., Lafourcade, P., Millet, L., Potop-Butucaru, M., Thierry-Mieg, Y., Tixeuil, S.: Formal verification of mobile robot protocols. Distrib. Comput. 29(6), 459–487 (2016)
Bhagat, S., Chaudhuri, S.G., Mukhopadhyaya, K.: Formation of general position by asynchronous mobile robots under one-axis agreement. In: Proceeding of 10th International ’l WS on Algorithms and Computation (WALCOM), LNCS, vol. 9627, pp. 80–91. Springer (2016)
Bramas, Q., Tixeuil, S.: Brief Announcement: Probabilistic asynchronous arbitrary pattern formation. In: Proceedings of 35th ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing (PODC) (2016)
Cicerone, S., Di Stefano, G., Navarra, A.: Asynchronous embedded pattern formation without orientation. In: Proceedings of 30th International ’l Symposium on Distributed Computing (DISC), LNCS, vol. 9888, pp. 85–98. Springer (2016)
Cicerone, S., Di Stefano, G., Navarra, A.: Asynchronous arbitrary pattern formation: the effects of a rigorous approach. Distrib. Comput. (2018). https://doi.org/10.1007/s00446-018-0325-7
Cicerone, S., Di Stefano, G., Navarra, A.: Gathering of robots on meeting-points: feasibility and optimal resolution algorithms. Distrib. Comput. 31(1), 1–50 (2018)
Cieliebak, M., Flocchini, P., Prencipe, G., Santoro, N.: Distributed computing by mobile robots: gathering. SIAM J. Comput. 41(4), 829–879 (2012)
Courtieu, P., Rieg, L., Tixeuil, S., Urbain, X.: Impossibility of gathering, a certification. Inf. Process. Lett. 115(3), 447–452 (2015)
Courtieu, P., Rieg, L., Tixeuil, S., Urbain, X.: Brief Announcement: Certified universal gathering in \(R^2\) for oblivious mobile robots. In: Proceedings of 35th ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing (PODC) (2016)
D’Angelo, G., Di Stefano, G., Klasing, R., Navarra, A.: Gathering of robots on anonymous grids and trees without multiplicity detection. Theor. Comput. Sci. 610, 158–168 (2016)
D’Angelo, G., Di Stefano, G., Navarra, A.: Gathering on rings under the look-compute-move model. Distrib. Comput. 27(4), 255–285 (2014)
D’Angelo, G., Di Stefano, G., Navarra, A., Nisse, N., Suchan, K.: Computing on rings by oblivious robots: a unified approach for different tasks. Algorithmica 72(4), 1055–1096 (2015)
D’Angelo, G., Navarra, A., Nisse, N.: A unified approach for gathering and exclusive searching on rings under weak assumptions. Distrib. Comput. 30(1), 17–48 (2017)
Das, S., Flocchini, P., Santoro, N., Yamashita, M.: Forming sequences of geometric patterns with oblivious mobile robots. Distrib. Comput. 28(2), 131–145 (2015)
D’Emidio, M., Frigioni, D., Navarra, A.: Characterizing the computational power of anonymous mobile robots. In: Proceedings of 36th IEEE International ’l Conference on Distributed Computing Systems, (ICDCS), pp. 293–302. IEEE (2016)
Di Stefano, G., Navarra, A.: Gathering of oblivious robots on infinite grids with minimum traveled distance. Inf. Comput. 254, 377–391 (2017)
Di Stefano, G., Navarra, A.: Optimal gathering of oblivious robots in anonymous graphs and its application on trees and rings. Distrib. Comput. 30(2), 75–86 (2017)
Dieudonné, Y., Labbani-Igbida, O., Petit, F.: Circle formation of weak mobile robots. TAAS 3(4), 16:1–16:20 (2008)
Doan, H.T.T., Bonnet, F., Ogata, K.: Model checking of a mobile robots perpetual exploration algorithm. In: Proceedings of 6th International ’l Work on Structured Object-Oriented Formal Language and Method (SOFL+MSVL), Lecture Notes in Computer Science, vol. 10189, pp. 201–219 (2017)
Donald, B.R., Jennings, J.S., Rus, D.: Information invariants for distributed manipulation. I. J. Robotics Res. 16(5), 673–702 (1997)
Flocchini, P., Prencipe, G., Santoro, N.: Distributed Computing by Oblivious Mobile Robots. Synthesis Lectures on Distributed Computing Theory. Morgan & Claypool Publishers, (2012)
Flocchini, P., Prencipe, G., Santoro, N., Viglietta, G.: Distributed computing by mobile robots: uniform circle formation. Distrib. Comput. 30, 413–457 (2017)
Flocchini, P., Prencipe, G., Santoro, N., Widmayer, P.: Gathering of asynchronous robots with limited visibility. Theor. Comput. Sci. 337, 147–168 (2005)
Flocchini, P., Prencipe, G., Santoro, N., Widmayer, P.: Arbitrary pattern formation by asynchronous, anonymous, oblivious robots. Theor. Comput. Sci. 407(1–3), 412–447 (2008)
Fujinaga, N., Ono, H., Kijima, S., Yamashita, M.: Pattern formation through optimum matching by oblivious corda robots. In: Proceedings of 14th International ’l Conference on Principles of Distributed Systems (OPODIS), LNCS, vol. 6490, pp. 1–15. Springer (2010)
Fujinaga, N., Yamauchi, Y., Kijima, S., Yamashita, M.: Asynchronous pattern formation by anonymous oblivious mobile robots. In: Proceedings of 26th International ’l Symposium on Distributed Computing (DISC), LNCS, vol. 7611, pp. 312–325. Springer (2012)
Fujinaga, N., Yamauchi, Y., Ono, H., Kijima, S., Yamashita, M.: Pattern formation by oblivious asynchronous mobile robots. SIAM J. Comput. 44(3), 740–785 (2015)
Ghike, S., Mukhopadhyaya, K.: A distributed algorithm for pattern formation by autonomous robots, with no agreement on coordinate compass. In: Proceedings of 6th International ’l Conference on Distributed Computing and Internet Technology, (ICDCIT), LNCS, vol. 5966, pp. 157–169. Springer (2010)
Izumi, T., Katayama, Y., Inuzuka, N., Wada, K.: Gathering autonomous mobile robots with dynamic compasses: An optimal result. In: Proceedings of 21st International ’l Symposium on Distributed Computing (DISC), LNCS, vol. 4731, pp. 298–312. Springer (2007)
Klasing, R., Kosowski, A., Navarra, A.: Taking advantage of symmetries: gathering of many asynchronous oblivious robots on a ring. Theor. Comput. Sci. 411, 3235–3246 (2010)
Mamino, M., Viglietta, G.: Square formation by asynchronous oblivious robots. In: Proceedings of the 28th Canadian Conference on Computational Geometry (CCCG), pp. 1–6 (2016)
Millet, L., Potop-Butucaru, M., Sznajder, N., Tixeuil, S.: On the synthesis of mobile robots algorithms: The case of ring gathering. In: Proceedings of 16th International ’l Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS), LNCS, vol. 8756, pp. 237–251. Springer (2014)
Parker, L.E.: On the design of behavior-based multi-robot teams. Adv. Robot. 10(6), 547–578 (1995)
Prencipe, G.: The effect of synchronicity on the behavior of autonomous mobile robot. Theory Comput. Syst. 38, 539–558 (2005)
Romanishin, J., Gilpin, K., Rus, D.: M-blocks: Momentum-driven, magnetic modular robots. In: Proceedings of IEEE/RSJ International ’l Conference on Intelligent Robots and Systems, pp. 4288–4295. IEEE (2013)
Suzuki, I., Yamashita, M.: Distributed anonymous mobile robots: Formation of geometric patterns. SIAM J. Comput. 28(4), 1347–1363 (1999)
Yamashita, M., Suzuki, I.: Characterizing geometric patterns formable by oblivious anonymous mobile robots. Theor. Comput. Sci. 411(26–28), 2433–2453 (2010)
Yamauchi, Y., Uehara, T., Kijima, S., Yamashita, M.: Plane formation by synchronous mobile robots in the three dimensional euclidean space. In: Proceedings of 29th International ’l Symposium on Distributed Computing (DISC), LNCS, vol. 9363, pp. 92–106. Springer (2015)
Yamauchi, Y., Uehara, T., Yamashita, M.: Brief Announcement: Pattern formation problem for synchronous mobile robots in the three dimensional euclidean space. In: Proceedings of 35th ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing (PODC) (2016)
Yamauchi, Y., Yamashita, M.: Randomized pattern formation algorithm for asynchronous oblivious mobile robots. In: Proceedings of 28th International ’l Symposium on Distributed Computing, (DISC), LNCS, vol. 8784, pp. 137–151. Springer (2014)
Author information
Authors and Affiliations
Corresponding author
Additional information
Preliminary results appeared in the Proceedings of the 30th Int.’l Symp. on Distributed Computing (DISC) 2016 [5]. The work has been supported in part by the European project “Geospatial based Environment for Optimisation Systems Addressing Fire Emergencies” (GEO-SAFE), contract no. H2020-691161, and by the Italian National Group for Scientific Computation (GNCS-INdAM) research project 2018 “Anti-Social Networks”.
Rights and permissions
About this article
Cite this article
Cicerone, S., Di Stefano, G. & Navarra, A. Embedded pattern formation by asynchronous robots without chirality. Distrib. Comput. 32, 291–315 (2019). https://doi.org/10.1007/s00446-018-0333-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00446-018-0333-7