Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
<mark>Journal publication date</mark> | 1/01/2022 |
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<mark>Journal</mark> | Combinatorics, Probability and Computing |
Issue number | 1 |
Volume | 31 |
Number of pages | 28 |
Pages (from-to) | 73-100 |
Publication Status | Published |
Early online date | 28/05/21 |
<mark>Original language</mark> | English |
We apply the power-of-two-choices paradigm to a random walk on a graph: rather than moving to a uniform random neighbour at each step, a controller is allowed to choose from two independent uniform random neighbours. We prove that this allows the controller to significantly accelerate the hitting and cover times in several natural graph classes. In particular, we show that the cover time becomes linear in the number n of vertices on discrete tori and bounded degree trees, of order O(n log log n) on bounded degree expanders, and of order O(n(log log n) 2) on the Erdős-Rényi random graph in a certain sparsely connected regime.We also consider the algorithmic question of computing an optimal strategy and prove a dichotomy in efficiency between computing strategies for hitting and cover times.