Completeness theorems for non-cryptographic fault-tolerant distributed computation
STOC '88 Proceedings of the twentieth annual ACM symposium on Theory of computing
Impossibility of distributed consensus with one faulty process
Journal of the ACM (JACM)
A N algorithm for mutual exclusion in decentralized systems
ACM Transactions on Computer Systems (TOCS)
The art of computer programming, volume 3: (2nd ed.) sorting and searching
The art of computer programming, volume 3: (2nd ed.) sorting and searching
The Byzantine Generals Problem
ACM Transactions on Programming Languages and Systems (TOPLAS)
A Distributed Algorithm for Minimum-Weight Spanning Trees
ACM Transactions on Programming Languages and Systems (TOPLAS)
On the optimal search problem: the case when the target distribution is unknown
SCCC '97 Proceedings of the 17th International Conference of the Chilean Computer Science Society
Capture of an intruder by mobile agents
Proceedings of the fourteenth annual ACM symposium on Parallel algorithms and architectures
Randomised Mutual Search for k2 Agents
DISC '01 Proceedings of the 15th International Conference on Distributed Computing
Developing and Refining an Adaptive Token-Passing Strategy
ICDCS '01 Proceedings of the The 21st International Conference on Distributed Computing Systems
Mobile agent rendezvous: a survey
SIROCCO'06 Proceedings of the 13th international conference on Structural Information and Communication Complexity
Finding short right-hand-on-the-wall walks in graphs
SIROCCO'05 Proceedings of the 12th international conference on Structural Information and Communication Complexity
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We introduce a search problem called “mutual search” where k agents, arbitrarily distributed over n sites, are required to locate one another by posing queries of the form “Anybody at site i?”. We ask for the least number of queries that is necessary and sufficient. For the case of two agents using deterministic protocols, we obtain the following worst-case results: In an oblivious setting (where all pre-planned queries are executed), there is no savings: n−1 queries are required and are sufficient. In a nonoblivious setting, we can exploit the paradigm of “no news is also news” to obtain significant savings: in the synchronous case 0.586n queries are required; in the asynchronous case 0.896n queries suffice and a fortiori 0.536n queries are required; for on agents using a synchronous deterministic protocol less than n queries suffice; there is a simple randomized protocol for two agents with worst-case expected 0.5n queries and all radomized protocols require at least 0.25n worst-case expected queries. The graph-theoretic framework we formulate for expressing and analyzing algorithms for this problem may be of independent interest.