On the influence of edges in first-passage percolation on $\mathbb{Z}^d$

Abstract: We study first-passage percolation on $\mathbb Z^d$, $d\ge 2$, with independent weights whose common distribution is compactly supported in $(0,\infty)$ with a uniformly-positive density. Given $\epsilon>0$ and $v\in\mathbb Z^d$, which edges have probability at least $\epsilon$ to lie on the geodesic between the origin and $v$? It is expected that all such edges lie at distance at most some $r(\epsilon)$ from either the origin or $v$, but this remains open in dimensions $d\ge 3$. We establish the closely-related fact that the number of such edges is at most some $C(\epsilon)$, uniformly in $v$. In addition, we prove a quantitative bound, allowing $\epsilon$ to tend to zero as $|v|$ tends to infinity, showing that there are at most $O\big(\epsilon^{-\frac{2d}{d-1}}(\log |v|)^C\big)$ such edges, uniformly in $\epsilon$ and $v$. The latter result addresses a problem raised by Benjamin-Kalai-Schramm (2003). Our technique further yields a strengthened version of a lower bound on transversal fluctuations due to Licea-Newman-Piza (1996).