Strict Convexity of the First-Passage Percolation Limit Shape

OPENMajorConjectureProposed c. 1965 · Canonical special case

Canonical statement

Assign independent mean-one exponential passage times to the nearest-neighbor edges of Zd\mathbb Z^d, d2d\ge2. Let BRd\mathcal B\subset\mathbb R^d be the deterministic compact convex limit shape from the first-passage percolation shape theorem. Then B\mathcal B is strictly convex: its boundary contains no nontrivial line segment.
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Assign independent mean-one exponential passage times to the nearest-neighbor edges of \(\mathbb Z^d\), \(d\ge2\). Let \(\mathcal B\subset\mathbb R^d\) be the deterministic compact convex limit shape from the first-passage percolation shape theorem. Then \(\mathcal B\) is strictly convex: its boundary contains no nontrivial line segment.

The first-passage percolation shape theorem produces a deterministic convex limit body [HammersleyWelsh1965FPP]. Its boundary is expected to be curved for continuous iid weights, yet standard techniques do not prove even the absence of a line segment for exponential edge times. The modern monograph records this as a basic geometric gap [AuffingerDamronHanson2017FPP]. The entry fixes a canonical distribution so it is a precise problem rather than a vague universality claim.

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