PreprintCC0arXiv
Very sharp distance and range transitions for random walk bridges on Ramanujan graphs
Abstract
For vertex-transitive Ramanujan graphs with logarithmic girth, a simple random walk bridge of length of order log N, where N is the size of the graph, has a maximum distance that changes from order √(log N) to order log N in a bounded critical window. We prove this by separating bridges whose lifts to the regular tree close from those whose lifts do not. A uniform two-term return estimate determines the probabilities of these two cases and the real-valued critical center. In the same O(1) window, the normalized range has a two-point limiting law whose mixture weights vary nontrivially across the window.
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BibTeX
@misc{benjamini2026very,
title = {{Very sharp distance and range transitions for random walk bridges on Ramanujan graphs}},
author = {Itai Benjamini},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.35213},
eprint = {2609.35213},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.35213},
note = {CC0},
}
RIS
TY - UNPB
TI - Very sharp distance and range transitions for random walk bridges on Ramanujan graphs
AU - Itai Benjamini
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.35213
UR - https://arxiv.org/abs/2609.35213
AB - For vertex-transitive Ramanujan graphs with logarithmic girth, a simple random walk bridge of length of order log N, where N is the size of the graph, has a maximum distance that changes from order √(log N) to order log N in a bounded critical window. We prove this by separating bridges whose lifts to the regular tree close from those whose lifts do not. A uniform two-term return estimate determines the probabilities of these two cases and the real-valued critical center. In the same O(1) window, the normalized range has a two-point limiting law whose mixture weights vary nontrivially across the window.
ER -