Conway–Guttman asymptotics conjecture for occurrences of length-four patterns

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Let Sn,r(q)S_{n,r}(q) denote the set of permutations of length nn with rr copies of the pattern qq, and let Sn(q)S_n(q) denote the set of permutations of length nn avoiding qq. For a pattern qq, write ∣Sn,r(q)∣|S_{n,r}(q)| and ∣Sn(q)∣|S_n(q)| for their cardinalities.

Conway–Guttman conjecture. For q∈{4321,4312}q \in \{4321,4312\}, there is a constant KK such that

∣Sn,r(q)∣∼K∣Sn(q)∣.|S_{n,r}(q)| \sim K|S_n(q)|.

For q∈{4123,3412,4231,4213,3142}q\in \{4123,3412,4231,4213,3142\}, there is a constant KK such that

∣Sn,r(q)∣∼Knr∣Sn(q)∣.|S_{n,r}(q)| \sim Kn^r|S_n(q)|.

This conjecture concerns the seven effective Wilf classes of patterns of length four and is supported by substantial numerical evidence. The paper proves asymptotic results for some of these patterns, but the stated general asymptotics remain conjectural.

References

Primary source

Michael Waite, “Permutations with a fixed number of occurrences of a pattern: A case generalizing 231”, arXiv:2603.21625 (2026).

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