Non-local Probes Do Not Help with Many Graph Problems
- Cite this paper as:
- Göös M., Hirvonen J., Levi R., Medina M., Suomela J. (2016) Non-local Probes Do Not Help with Many Graph Problems. In: Gavoille C., Ilcinkas D. (eds) Distributed Computing. DISC 2016. Lecture Notes in Computer Science, vol 9888. Springer, Berlin, Heidelberg
This work bridges the gap between distributed and centralised models of computing in the context of sublinear-time graph algorithms. A priori, typical centralised models of computing (e.g., parallel decision trees or centralised local algorithms) seem to be much more powerful than distributed message-passing algorithms: centralised algorithms can directly probe any part of the input, while in distributed algorithms nodes can only communicate with their immediate neighbours. We show that for a large class of graph problems, this extra freedom does not help centralised algorithms at all: efficient stateless deterministic centralised local algorithms can be simulated with efficient distributed message-passing algorithms. In particular, this enables us to transfer existing lower bound results from distributed algorithms to centralised local algorithms.