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OP-12040OpenCombinatorics

Stanley–Wilf limit for the permutation pattern 13241324 (C30C_{30})

Stanley–Wilf limit for the permutation pattern 13241324: determine C30C_{30} or improve its bounds; the repository records 10.27 (lower) and 13.5 (upper).

Editorial MSC2020 classification. Original article codes and source evidence are recorded in the literature directory.

Licensed source statementAs of Repository table at commit 2c1968c (2026-09-26); open while the recorded lower and upper bounds differSource & evidence ↓

Problem statement

Let Avn(1324)\mathrm{Av}_n(1324) be the set of permutations of {1,2,…,n}\{1,2,\dots,n\} that avoid the permutation pattern 13241324, and let

Sn(1324):=∣Avn(1324)∣.S_n(1324) := |\mathrm{Av}_n(1324)|.

[CJS12-def-Sn]

The Stanley–Wilf limit (growth constant) for the pattern 13241324 is

C30  :=  lim⁡n→∞(Sn(1324))1/n.C_{30} \;:=\; \lim_{n\to\infty} \bigl(S_n(1324)\bigr)^{1/n}.

[CJS12-def-Ltau]

Equivalently, C30=gr(Av(1324))C_{30} = \mathrm{gr}(\mathrm{Av}(1324)), the growth rate of the permutation class avoiding 13241324.

[BBEPP2017-def-gr]

This limit is known to exist (and to be finite) for every fixed pattern, as a consequence of Marcus–Tardos and Arratia.

[CJS12-mt-expbound] [CJS12-arratia-exists]

Lean 4

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Background

  • Determining the exact value of C30C_{30} remains open. [BBEPP2017-open]

  • The best current rigorous bounds are 10.27≤C30≤13.510.27 \le C_{30} \le 13.5. [BBEPP2017-t1-thiswork]

  • Claesson, Jelínek and Steingrímsson conjectured a statement about 13241324-avoiding permutations with a fixed number of inversions, which (if true) would imply the improved upper bound

C30≤eπ2/3≈13.001954;C_{30} \le e^{\pi \sqrt{2/3}} \approx 13.001954;

see [CJS12] (and [BBEPP2017] for a brief summary). [CJS12-cond-ub] [BBEPP2017-cond-ub]

  • Conway, Guttmann and Zinn-Justin have analysed the series for the number of 13241324-avoiding permutations in SnS_n and give a numerical estimate for C30C_{30} of 11.600±0.00311.600 \pm 0.003. They also conjecture that ∣Avn(1324)∣|\mathrm{Av}_n(1324)| behaves asymptotically as
A⋅μn⋅λn⋅nα(n→∞)A\cdot \mu^n \cdot \lambda^{\sqrt{n}} \cdot n^\alpha \qquad (n\to\infty)

for certain estimated constants A,λ,αA,\lambda,\alpha; see [BBEPP2017] for a summary. [BBEPP2017-estimate] [BBEPP2017-asymptotic]

References (from the repository page)

  • [BBEPP2017] Bevan, David; Brignall, Robert; Elvey Price, Andrew; Pantone, Jay. A structural characterisation of Av(1324) and new bounds on its growth rate. Preprint (2017), last revised 2019. Google Scholar. arXiv PDF. Publisher entry

  • [BBEPP2017-open] loc: arXiv v3 PDF p.1, Section 1 (Introduction). quote: “In contrast, even the exponential growth rate of Av(1324)\mathrm{Av}(1324) remains to be determined exactly.”

  • [BBEPP2017-def-gr] loc: arXiv v3 PDF p.2, Section 1 (Introduction). quote: “The exponential growth rate of the class Av(π)\mathrm{Av}(\pi) is gr(Av(π))=lim sup⁡n→∞∣Avn(π)∣1/n\mathrm{gr}(\mathrm{Av}(\pi)) = \limsup_{n\to\infty} |\mathrm{Av}_n(\pi)|^{1/n}, where Avn(π)\mathrm{Av}_n(\pi) denotes the set of permutations of length nn that avoid π\pi. This limit is known to exist as a consequence of the resolution of the Stanley-Wilf conjecture by Marcus and Tardos [26].”

  • [BBEPP2017-t1-ub-288] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2004: Bóna [5] 288288 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-lb-9] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2005: Bóna [6] 99 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-lb-9.47] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2006: Albert et al. [1] 9.479.47 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-ub-16] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2012: Claesson, Jelínek and Steingrímsson [13] 1616 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-ub-13.93] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2014: Bóna [8] 13.9313.93 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-lb-9.81] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2015: Bevan [3] 9.819.81 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-ub-13.74] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper 2015: Bóna [9] 13.7413.74 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-t1-thiswork] loc: arXiv v3 PDF p.2, Section 1 (Introduction), Table 1. quote: “Lower Upper This work 10.2710.27 13.513.5 Table 1: A chronology of lower and upper bounds for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324))”

  • [BBEPP2017-cond-ub] loc: arXiv v3 PDF p.2, Section 1 (Introduction). quote: “In addition to these, Claesson, Jelínek and Steingrímsson [13] make a conjecture regarding the number of 13241324-avoiders of each length that have a fixed number of inversions, which if proven would yield an improved upper bound of eπ2/3≈13.002e^{\pi\sqrt{2/3}} \approx 13.002.”

  • [BBEPP2017-estimate] loc: arXiv v3 PDF p.2, Section 1 (Introduction). quote: “Conway, Guttmann and Zinn-Justin [14, 15] have analysed the numbers and give a numerical estimate for gr(Av(1324))\mathrm{gr}(\mathrm{Av}(1324)) of μ≈11.600±0.003\mu \approx 11.600 \pm 0.003.”

  • [BBEPP2017-asymptotic] loc: arXiv v3 PDF p.2, Section 1 (Introduction). quote: “They also conjecture that ∣Avn(1324)∣|\mathrm{Av}_n(1324)| behaves asymptotically as A⋅μn⋅λn⋅nαA\cdot \mu^n \cdot \lambda^{\sqrt{n}} \cdot n^\alpha, for certain estimated constants AA, λ\lambda and α\alpha.”

  • [B04] Bóna, Miklós. A simple proof for the exponential upper bound for some tenacious patterns. Advances in Applied Mathematics 33 (2004), no. 1, 192–198. DOI: 10.1016/j.aam.2003.07.003. Google Scholar

  • [B05] Bóna, Miklós. The limit of a Stanley–Wilf sequence is not always rational, and layered patterns beat monotone patterns. J. Combin. Theory Ser. A 110 (2005), no. 2, 223–235. DOI: 10.1016/j.jcta.2004.07.014. Google Scholar. arXiv PDF

  • [AERWZ] Albert, M. H.; Elder, M.; Rechnitzer, A.; Westcott, P.; Zabrocki, M. On the Stanley–Wilf limit of 4231-avoiding permutations and a conjecture of Arratia. Adv. Appl. Math. 36 (2006), no. 2, 96–105. DOI: 10.1016/j.aam.2005.05.007. Google Scholar. arXiv PDF

  • [CJS12] Claesson, A.; Jelínek, V.; Steingrímsson, E. Upper bounds for the Stanley–Wilf limit of 1324 and other layered patterns. J. Combin. Theory Ser. A 119 (2012), no. 8, 1680–1691. DOI: 10.1016/j.jcta.2012.05.006. Google Scholar. arXiv PDF

  • [CJS12-def-Sn] loc: arXiv v1 PDF p.1, Section 1 (Introduction). quote: “For a permutation pattern τ\tau, let Sn(τ)S_n(\tau) be the set of permutations of length nn avoiding τ\tau, and let Sn(τ)S_n(\tau) be the cardinality of Sn(τ)S_n(\tau).”

  • [CJS12-def-Ltau] loc: arXiv v1 PDF p.1, Section 1 (Introduction). quote: “The limit L(τ)=lim⁡n→∞Sn(τ)1/nL(\tau) = \lim_{n\to\infty} S_n(\tau)^{1/n} is called the Stanley-Wilf limit for τ\tau.”

  • [CJS12-mt-expbound] loc: arXiv v1 PDF p.1, Section 1 (Introduction). quote: “In 2004, Marcus and Tardos [15] proved the Stanley-Wilf conjecture, stating that, for any pattern τ\tau, Sn(τ)<CnS_n(\tau) < C^n for some constant CC depending only on τ\tau.”

  • [CJS12-arratia-exists] loc: arXiv v1 PDF p.1, Section 1 (Introduction). quote: “Arratia [3] has shown that this limit exists for any pattern τ\tau.”

  • [CJS12-cond-ub] loc: arXiv v1 PDF p.1, Abstract. quote: “We also conjecture that, for any k≥0k \ge 0, the set of 13241324-avoiding permutations with kk inversions contains at least as many permutations of length n+1n+1 as those of length nn. We show that if this is true then the Stanley-Wilf limit for 13241324 is at most eπ2/3≃13.001954e^{\pi\sqrt{2/3}} \simeq 13.001954.”

  • [B14a] Bóna, Miklós. A new upper bound for 1324-avoiding permutations. Combinatorics, Probability and Computing 23 (2014), no. 5, 717–724. DOI: 10.1017/S0963548314000091. Google Scholar. arXiv PDF

  • [B14b] Bóna, Miklós. A new record for 1324-avoiding permutations. European J. Math. 1 (2015), no. 1, 198–206. DOI: 10.1007/s40879-014-0020-6. Google Scholar. arXiv PDF

  • [Bev] Bevan, David. Permutations avoiding 1324 and patterns in Łukasiewicz paths. J. London Math. Soc. 92 (2015), no. 1, 105–122. DOI: 10.1112/jlms/jdv020. Google Scholar. arXiv PDF

Progress & source assessment

Repository table (commit 2c1968c, 26 September 2026): best known lower bound 10.27; best known upper bound 13.5. Values marked with an asterisk have minimal verification.

Known upper bounds

Bound Reference Comments
288288 [B04] Upper bound recorded in Table 1 of [BBEPP2017]. [BBEPP2017-t1-ub-288]
1616 [CJS12] Upper bound recorded in Table 1 of [BBEPP2017]. [BBEPP2017-t1-ub-16]
13.9313.93 [B14a] Upper bound recorded in Table 1 of [BBEPP2017]. [BBEPP2017-t1-ub-13.93]
13.7413.74 [B14b] Upper bound recorded in Table 1 of [BBEPP2017]. [BBEPP2017-t1-ub-13.74]
13.513.5 [BBEPP2017] Current best rigorous upper bound. [BBEPP2017-t1-thiswork]

Known lower bounds

Bound Reference Comments
99 [B05] Lower bound recorded in Table 1 of BBEPP2017. [BBEPP2017-t1-lb-9]
9.479.47 [AERWZ] Lower bound recorded in Table 1 of BBEPP2017. [BBEPP2017-t1-lb-9.47]
9.819.81 [Bev] Lower bound recorded in Table 1 of BBEPP2017. [BBEPP2017-t1-lb-9.81]
10.2710.27 [BBEPP2017] Current best rigorous lower bound. [BBEPP2017-t1-thiswork]
References
  1. [1]Davis, Damek; Ivanisvili, Paata; Tao, Terence (maintainers). Optimization Constants in Mathematics, github.com/teorth/optimizationproblems (commit 2c1968c, 26 September 2026). — Stanley–Wilf limit for the permutation pattern $1324$ ($C_{30}$) linkApache-2.0 (repository license); constant pages reproduced with attribution; repository references retained.

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