OpenFrontiers
← Back to the index

Erdős #529 · geometry / probability

Let dk(n)d_k(n) be the expected distance from the origin after taking nn random steps from the origin in Zk\mathbb{Z}^k (conditional on no self intersections) - that is, a [self-avoiding walk](<https://en.wikipedia.org/wik…

Source reports OPENAs of 2026-09-08Source & evidence ↓

Problem statement

Let dk(n)d_k(n) be the expected distance from the origin after taking nn random steps from the origin in Zk\mathbb{Z}^k (conditional on no self intersections) - that is, a self-avoiding walk. Is it true that

lim⁡n→∞d2(n)n1/2=∞?\lim_{n\to \infty}\frac{d_2(n)}{n^{1/2}}= \infty?

Is it true that

dk(n)≪n1/2d_k(n)\ll n^{1/2}

for k≥3k\geq 3?

Lean 4

Not yet attached

No Lean statement or proof is attached yet. Have a formalization? Share its source to add it to this problem.

Background

Slade [Sl87] proved that, for kk sufficiently large, dk(n)∼Dn1/2d_k(n)\sim Dn^{1/2} for some constant D>0D>0 (independent of kk). Hara and Slade ([HaSl91] and [HaSl92]) proved this for all k≥5k\geq 5.

For k=2k=2 Duminil-Copin and Hammond [DuHa13] have proved that d2(n)=o(n)d_2(n)=o(n).

It is now conjectured that dk(n)≪n1/2d_k(n)\ll n^{1/2} is false for k=3k=3 and k=4k=4, and more precisely (see for example Section 1.4 of [MaSl93]) that d2(n)∼Dn3/4d_2(n)\sim Dn^{3/4}, d3(n)∼nνd_3(n)\sim n^{\nu} where ν≈0.59\nu\approx 0.59, and d4(n)∼D(log⁡n)1/8n1/2d_4(n)\sim D(\log n)^{1/8}n^{1/2}.

Madras and Slade [MaSl93] have a monograph on the topic of self-avoiding walks.

See also [528].

Progress & source assessment

The source labels this entry OPEN in the 2026-09-08 snapshot. Editorial progress notes are reproduced as source commentary, not independently verified results. Prize amounts and Lean badges at the source are not local awards or verification.

References
  1. [1]Thomas Bloom (ed.), Erdős Problems #529 link

Recorded progress

Add yours →

Nothing recorded yet. A pointer to a paper the entry is missing counts.

Machine attempts

0 recorded

Attempts run against the statement below and are recorded in full, including the failures. The point is to stop the next model — and the next person — from re-walking a road that is already known to end. Each attempt costs 25 credits.

No machine attempts recorded.

Sign in to run an attempt. New accounts start with enough credits for ten.

Discussion

0 notes

Notes are for clarifying the statement, flagging a missing reference, or recording why an approach fails. Claimed solutions belong in a submission, where they can be reviewed.

No notes yet.

Sign in to add a note.