Impossibility of distributed consensus with one faulty process
Journal of the ACM (JACM)
SIAM Journal on Control and Optimization
Minimax Rendezvous on the Line
SIAM Journal on Control and Optimization
Asymmetric rendezvous on the plane
Proceedings of the fourteenth annual symposium on Computational geometry
Distributed Anonymous Mobile Robots: Formation of Geometric Patterns
SIAM Journal on Computing
Agent Rendezvous: A Dynamic Symmetry-Breaking Problem
ICALP '96 Proceedings of the 23rd International Colloquium on Automata, Languages and Programming
Gathering of Asynchronous Oblivious Robots with Limited Visibility
STACS '01 Proceedings of the 18th Annual Symposium on Theoretical Aspects of Computer Science
Two Dimensional Rendezvous Search
Operations Research
Mobile Agent Rendezvous in a Ring
ICDCS '03 Proceedings of the 23rd International Conference on Distributed Computing Systems
Convergence Properties of the Gravitational Algorithm in Asynchronous Robot Systems
SIAM Journal on Computing
Fault-Tolerant Gathering Algorithms for Autonomous Mobile Robots
SIAM Journal on Computing
Asynchronous deterministic rendezvous in graphs
Theoretical Computer Science
Networks
Deterministic Rendezvous in Graphs
Algorithmica
Deterministic rendezvous, treasure hunts and strongly universal exploration sequences
SODA '07 Proceedings of the eighteenth annual ACM-SIAM symposium on Discrete algorithms
Convergence of Autonomous Mobile Robots with Inaccurate Sensors and Movements
SIAM Journal on Computing
Solving the robots gathering problem
ICALP'03 Proceedings of the 30th international conference on Automata, languages and programming
Characterizing geometric patterns formable by oblivious anonymous mobile robots
Theoretical Computer Science
Tell me where i am so i can meet you sooner: asynchronous rendezvous with location information
ICALP'10 Proceedings of the 37th international colloquium conference on Automata, languages and programming: Part II
Almost optimal asynchronous rendezvous in infinite multidimensional grids
DISC'10 Proceedings of the 24th international conference on Distributed computing
An agent exploration in unknown undirected graphs with whiteboards
Proceedings of the Third International Workshop on Reliability, Availability, and Security
Proceedings of the twenty-third annual ACM-SIAM symposium on Discrete Algorithms
How to meet in anonymous network
SIROCCO'06 Proceedings of the 13th international conference on Structural Information and Communication Complexity
Optimal deterministic ring exploration with oblivious asynchronous robots
SIROCCO'10 Proceedings of the 17th international conference on Structural Information and Communication Complexity
Asynchronous rendezvous of anonymous agents in arbitrary graphs
OPODIS'11 Proceedings of the 15th international conference on Principles of Distributed Systems
The Gathering Problem for Two Oblivious Robots with Unreliable Compasses
SIAM Journal on Computing
How to meet asynchronously (almost) everywhere
ACM Transactions on Algorithms (TALG)
How to gather asynchronous oblivious robots on anonymous rings
DISC'12 Proceedings of the 26th international conference on Distributed Computing
Linear time and space gathering of anonymous mobile agents in asynchronous trees
Theoretical Computer Science
How to meet asynchronously at polynomial cost
Proceedings of the 2013 ACM symposium on Principles of distributed computing
Deterministic polynomial approach in the plane
ICALP'13 Proceedings of the 40th international conference on Automata, Languages, and Programming - Volume Part II
Hi-index | 5.23 |
Asynchrony is one of the main challenges in distributed computing. Some tasks, such as distributed Byzantine consensus, are impossible in the asynchronous setting, while they can be carried out synchronously. For other tasks, such as rendezvous in arbitrary graphs, the best known synchronous algorithm has cost much lower than the best asynchronous one. Various degrees of asynchrony and synchrony and comparisons between them in terms of feasibility of distributed tasks have been particularly intensely studied in the context of mobile agents computing. However, somewhat surprisingly, there are no results showing a provable difference of cost between the synchronous and asynchronous versions of a task executed by mobile agents. The aim of this paper is to fill up this gap. We show for the first time that for some natural task executed by mobile agents in a network, the optimal cost of its deterministic solution in the asynchronous setting has higher order of magnitude than that in the synchronous scenario. The task for which we show this difference is well-studied: that of rendezvous of two agents in an infinite oriented grid. More precisely, we consider two agents with distinct integer labels starting at a distance D in the infinite oriented grid. Each agent knows D and its own label but not the label of the other agent and it does not know the position of the other agent relative to its own. Agents do not have any global system of coordinates. They have to meet in a node or inside an edge of the grid, and the cost of a rendezvous algorithm is the number of edge traversals by both agents until the meeting. We show that in the synchronous scenario rendezvous can be performed at cost O(D@?), where @? is the length of the (binary representation of the) smaller label, while cost @W(D^2+D@?) is needed for asynchronous completion of rendezvous. Hence, for instances with @?=o(D), the optimal cost of asynchronous rendezvous is asymptotically larger than that of synchronous rendezvous.