Monotonic growth-constant conjecture for 132-avoiding permutations with bounded adjacency

Let An(m)A_n^{(m)} be the class of permutations in SnS_n that avoid 132132 and satisfy ∣πi+1−πi∣≤m|\pi_{i+1}-\pi_i|\leq m, with mm fixed. Define the exponential growth constant, when the limit exists, by

αm=lim⁡n→∞(An(m))1/n.\alpha_m = \lim_{n\to\infty} (A_n^{(m)})^{1/n}.

Monotonic growth-constant conjecture. For fixed mm, the limit αm\alpha_m exists, and

1=α1<α2<α3<⋯<4.1=\alpha_1<\alpha_2<\alpha_3<\cdots<4.

Moreover,

lim⁡m→∞αm=4.\lim_{m\to\infty}\alpha_m=4.

The known cases include growth rate 11 for m=1m=1, growth constant approximately 1.465571.46557 for m=2m=2, and the Catalan growth rate 44 when the adjacency bound is at least n−1n-1. The strict monotonicity and limiting assertion remain conjectural in the source.

References

Primary source

Nathaniel Nadler, “On 132-Avoiding Permutations with an Adjacency Constraint”, arXiv:2604.22135 (2026).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.