Van der Waerden number

Last updated July 10, 2024

Van der Waerden's theorem states that for any positive integers r and k there exists a positive integer N such that if the integers {1, 2, ..., N} are colored, each with one of r different colors, then there are at least k integers in arithmetic progression all of the same color. The smallest such N is the van der Waerden numberW(r, k).

Tables of Van der Waerden numbers

There are two cases in which the van der Waerden number W(r, k) is easy to compute: first, when the number of colors r is equal to 1, one has W(1, k) = k for any integer k, since one color produces only trivial colorings RRRRR...RRR (for the single color denoted R). Second, when the length k of the forced arithmetic progression is 2, one has W(r, 2) = r + 1, since one may construct a coloring that avoids arithmetic progressions of length 2 by using each color at most once, but using any color twice creates a length-2 arithmetic progression. (For example, for r = 3, the longest coloring that avoids an arithmetic progression of length 2 is RGB.) There are only seven other van der Waerden numbers that are known exactly. The table below gives exact values and bounds for values of W(r, k); values are taken from Rabung and Lotts except where otherwise noted.^[1]

k\r	2 colors	3 colors	4 colors	5 colors	6 colors
3	9^[2]	27^[2]	76^[3]	>170	>225
4	35^[2]	293^[4]	>1,048	>2,254	>9,778
5	178^[5]	>2,173	>17,705	>98,741^[6]	>98,748
6	1,132^[7]	>11,191	>157,209^[8]	>786,740^[8]	>1,555,549^[8]
7	>3,703	>48,811	>2,284,751^[8]	>15,993,257^[8]	>111,952,799^[8]
8	>11,495	>238,400	>12,288,155^[8]	>86,017,085^[8]	>602,119,595^[8]
9	>41,265	>932,745	>139,847,085^[8]	>978,929,595^[8]	>6,852,507,165^[8]
10	>103,474	>4,173,724	>1,189,640,578^[8]	>8,327,484,046^[8]	>58,292,388,322^[8]
11	>193,941	>18,603,731	>3,464,368,083^[8]	>38,108,048,913^[8]	>419,188,538,043 ^[8]

Some lower bound colorings computed using SAT approach by Marijn J.H. Heule ^[6] can be found on github project page.

Van der Waerden numbers with r ≥ 2 are bounded above by

W(r,k)\leq 2^{2^{r^{2^{2^{k+9}}}}}

as proved by Gowers.^[9]

For a prime number p, the 2-color van der Waerden number is bounded below by

p\cdot 2^{p}\leq W(2,p+1),

as proved by Berlekamp.^[10]

One sometimes also writes w(r; k₁, k₂, ..., k_r) to mean the smallest number w such that any coloring of the integers {1, 2, ..., w} with r colors contains a progression of length k_i of color i, for some i. Such numbers are called off-diagonal van der Waerden numbers. Thus W(r, k) = w(r; k, k, ..., k). Following is a list of some known van der Waerden numbers:

Known van der Waerden numbers
w(r;k₁, k₂, …, k_r)	Value	Reference
w(2; 3,3)	9	Chvátal ^[2]
w(2; 3,4)	18	Chvátal ^[2]
w(2; 3,5)	22	Chvátal ^[2]
w(2; 3,6)	32	Chvátal ^[2]
w(2; 3,7)	46	Chvátal ^[2]
w(2; 3,8)	58	Beeler and O'Neil ^[3]
w(2; 3,9)	77	Beeler and O'Neil ^[3]
w(2; 3,10)	97	Beeler and O'Neil ^[3]
w(2; 3,11)	114	Landman, Robertson, and Culver ^[11]
w(2; 3,12)	135	Landman, Robertson, and Culver ^[11]
w(2; 3,13)	160	Landman, Robertson, and Culver ^[11]
w(2; 3,14)	186	Kouril ^[12]
w(2; 3,15)	218	Kouril ^[12]
w(2; 3,16)	238	Kouril ^[12]
w(2; 3,17)	279	Ahmed ^[13]
w(2; 3,18)	312	Ahmed ^[13]
w(2; 3,19)	349	Ahmed, Kullmann, and Snevily ^[14]
w(2; 3,20)	389	Ahmed, Kullmann, and Snevily ^[14] (conjectured); Kouril ^[15] (verified)
w(2; 4,4)	35	Chvátal ^[2]
w(2; 4,5)	55	Chvátal ^[2]
w(2; 4,6)	73	Beeler and O'Neil ^[3]
w(2; 4,7)	109	Beeler ^[16]
w(2; 4,8)	146	Kouril ^[12]
w(2; 4,9)	309	Ahmed ^[17]
w(2; 5,5)	178	Stevens and Shantaram ^[5]
w(2; 5,6)	206	Kouril ^[12]
w(2; 5,7)	260	Ahmed ^[18]
w(2; 6,6)	1132	Kouril and Paul ^[7]
w(3; 2, 3, 3)	14	Brown ^[19]
w(3; 2, 3, 4)	21	Brown ^[19]
w(3; 2, 3, 5)	32	Brown ^[19]
w(3; 2, 3, 6)	40	Brown ^[19]
w(3; 2, 3, 7)	55	Landman, Robertson, and Culver ^[11]
w(3; 2, 3, 8)	72	Kouril ^[12]
w(3; 2, 3, 9)	90	Ahmed ^[20]
w(3; 2, 3, 10)	108	Ahmed ^[20]
w(3; 2, 3, 11)	129	Ahmed ^[20]
w(3; 2, 3, 12)	150	Ahmed ^[20]
w(3; 2, 3, 13)	171	Ahmed ^[20]
w(3; 2, 3, 14)	202	Kouril ^[4]
w(3; 2, 4, 4)	40	Brown ^[19]
w(3; 2, 4, 5)	71	Brown ^[19]
w(3; 2, 4, 6)	83	Landman, Robertson, and Culver ^[11]
w(3; 2, 4, 7)	119	Kouril ^[12]
w(3; 2, 4, 8)	157	Kouril ^[4]
w(3; 2, 5, 5)	180	Ahmed ^[20]
w(3; 2, 5, 6)	246	Kouril ^[4]
w(3; 3, 3, 3)	27	Chvátal ^[2]
w(3; 3, 3, 4)	51	Beeler and O'Neil ^[3]
w(3; 3, 3, 5)	80	Landman, Robertson, and Culver ^[11]
w(3; 3, 3, 6)	107	Ahmed ^[17]
w(3; 3, 4, 4)	89	Landman, Robertson, and Culver ^[11]
w(3; 4, 4, 4)	293	Kouril ^[4]
w(4; 2, 2, 3, 3)	17	Brown ^[19]
w(4; 2, 2, 3, 4)	25	Brown ^[19]
w(4; 2, 2, 3, 5)	43	Brown ^[19]
w(4; 2, 2, 3, 6)	48	Landman, Robertson, and Culver ^[11]
w(4; 2, 2, 3, 7)	65	Landman, Robertson, and Culver ^[11]
w(4; 2, 2, 3, 8)	83	Ahmed ^[20]
w(4; 2, 2, 3, 9)	99	Ahmed ^[20]
w(4; 2, 2, 3, 10)	119	Ahmed ^[20]
w(4; 2, 2, 3, 11)	141	Schweitzer ^[21]
w(4; 2, 2, 3, 12)	163	Kouril ^[15]
w(4; 2, 2, 4, 4)	53	Brown ^[19]
w(4; 2, 2, 4, 5)	75	Ahmed ^[20]
w(4; 2, 2, 4, 6)	93	Ahmed ^[20]
w(4; 2, 2, 4, 7)	143	Kouril ^[4]
w(4; 2, 3, 3, 3)	40	Brown ^[19]
w(4; 2, 3, 3, 4)	60	Landman, Robertson, and Culver ^[11]
w(4; 2, 3, 3, 5)	86	Ahmed ^[20]
w(4; 2, 3, 3, 6)	115	Kouril ^[15]
w(4; 3, 3, 3, 3)	76	Beeler and O'Neil ^[3]
w(5; 2, 2, 2, 3, 3)	20	Landman, Robertson, and Culver ^[11]
w(5; 2, 2, 2, 3, 4)	29	Ahmed ^[20]
w(5; 2, 2, 2, 3, 5)	44	Ahmed ^[20]
w(5; 2, 2, 2, 3, 6)	56	Ahmed ^[20]
w(5; 2, 2, 2, 3, 7)	72	Ahmed ^[20]
w(5; 2, 2, 2, 3, 8)	88	Ahmed ^[20]
w(5; 2, 2, 2, 3, 9)	107	Kouril ^[4]
w(5; 2, 2, 2, 4, 4)	54	Ahmed ^[20]
w(5; 2, 2, 2, 4, 5)	79	Ahmed ^[20]
w(5; 2, 2, 2, 4, 6)	101	Kouril ^[4]
w(5; 2, 2, 3, 3, 3)	41	Landman, Robertson, and Culver ^[11]
w(5; 2, 2, 3, 3, 4)	63	Ahmed ^[20]
w(5; 2, 2, 3, 3, 5)	95	Kouril ^[15]
w(6; 2, 2, 2, 2, 3, 3)	21	Ahmed ^[20]
w(6; 2, 2, 2, 2, 3, 4)	33	Ahmed ^[20]
w(6; 2, 2, 2, 2, 3, 5)	50	Ahmed ^[20]
w(6; 2, 2, 2, 2, 3, 6)	60	Ahmed ^[20]
w(6; 2, 2, 2, 2, 4, 4)	56	Ahmed ^[20]
w(6; 2, 2, 2, 3, 3, 3)	42	Ahmed ^[20]
w(7; 2, 2, 2, 2, 2, 3, 3)	24	Ahmed ^[20]
w(7; 2, 2, 2, 2, 2, 3, 4)	36	Ahmed ^[20]
w(7; 2, 2, 2, 2, 2, 3, 5)	55	Ahmed ^[17]
w(7; 2, 2, 2, 2, 2, 3, 6)	65	Ahmed ^[18]
w(7; 2, 2, 2, 2, 2, 4, 4)	66	Ahmed ^[18]
w(7; 2, 2, 2, 2, 3, 3, 3)	45	Ahmed ^[18]
w(8; 2, 2, 2, 2, 2, 2, 3, 3)	25	Ahmed ^[20]
w(8; 2, 2, 2, 2, 2, 2, 3, 4)	40	Ahmed ^[17]
w(8; 2, 2, 2, 2, 2, 2, 3, 5)	61	Ahmed ^[18]
w(8; 2, 2, 2, 2, 2, 2, 3, 6)	71	Ahmed ^[18]
w(8; 2, 2, 2, 2, 2, 2, 4, 4)	67	Ahmed ^[18]
w(8; 2, 2, 2, 2, 2, 3, 3, 3)	49	Ahmed ^[18]
w(9; 2, 2, 2, 2, 2, 2, 2, 3, 3)	28	Ahmed ^[20]
w(9; 2, 2, 2, 2, 2, 2, 2, 3, 4)	42	Ahmed ^[18]
w(9; 2, 2, 2, 2, 2, 2, 2, 3, 5)	65	Ahmed ^[18]
w(9; 2, 2, 2, 2, 2, 2, 3, 3, 3)	52	Ahmed ^[18]
w(10; 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	31	Ahmed ^[18]
w(10; 2, 2, 2, 2, 2, 2, 2, 2, 3, 4)	45	Ahmed ^[18]
w(10; 2, 2, 2, 2, 2, 2, 2, 2, 3, 5)	70	Ahmed ^[18]
w(11; 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	33	Ahmed ^[18]
w(11; 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 4)	48	Ahmed ^[18]
w(12; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	35	Ahmed ^[18]
w(12; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 4)	52	Ahmed ^[18]
w(13; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	37	Ahmed ^[18]
w(13; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 4)	55	Ahmed ^[18]
w(14; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	39	Ahmed ^[18]
w(15; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	42	Ahmed ^[18]
w(16; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	44	Ahmed ^[18]
w(17; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	46	Ahmed ^[18]
w(18; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	48	Ahmed ^[18]
w(19; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	50	Ahmed ^[18]
w(20; 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3)	51	Ahmed ^[18]

Van der Waerden numbers are primitive recursive, as proved by Shelah;^[22] in fact he proved that they are (at most) on the fifth level ${\mathcal {E}}^{5}$ of the Grzegorczyk hierarchy.

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References

↑ Rabung, John; Lotts, Mark (2012). "Improving the use of cyclic zippers in finding lower bounds for van der Waerden numbers". Electron. J. Combin. 19 (2). doi: 10.37236/2363 . MR 2928650.
1 2 3 4 5 6 7 8 9 10 11 Chvátal, Vašek (1970). "Some unknown van der Waerden numbers". In Guy, Richard; Hanani, Haim; Sauer, Norbert; et al. (eds.). Combinatorial Structures and Their Applications. New York: Gordon and Breach. pp. 31–33. MR 0266891.
1 2 3 4 5 6 7 Beeler, Michael D.; O'Neil, Patrick E. (1979). "Some new van der Waerden numbers". Discrete Mathematics . 28 (2): 135–146. doi: 10.1016/0012-365x(79)90090-6 . MR 0546646.
1 2 3 4 5 6 7 8 Kouril, Michal (2012). "Computing the van der Waerden number W(3,4)=293". Integers. 12: A46. MR 3083419.
1 2 Stevens, Richard S.; Shantaram, R. (1978). "Computer-generated van der Waerden partitions". Mathematics of Computation . 32 (142): 635–636. doi: 10.1090/s0025-5718-1978-0491468-x . MR 0491468.
1 2 Heule, MarijnJ (2017). "Avoiding triples in arithmetic progression" (PDF). Journal of Combinatorics. 8: 391–422.
1 2 Kouril, Michal; Paul, Jerome L. (2008). "The Van der Waerden Number W(2,6) is 1132". Experimental Mathematics . 17 (1): 53–61. doi:10.1080/10586458.2008.10129025. MR 2410115. S2CID 1696473.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Monroe, Daniel (2019). "New Lower Bounds for van der Waerden Numbers Using Distributed Computing". arXiv: 1603.03301 [math.CO].
↑ Gowers, Timothy (2001). "A new proof of Szemerédi's theorem" (PDF). Geom. Funct. Anal. 11 (3): 465–588. doi:10.1007/s00039-001-0332-9. MR 1844079. S2CID 124324198.
↑ Berlekamp, E. (1968). "A construction for partitions which avoid long arithmetic progressions". Canadian Mathematical Bulletin . 11 (3): 409–414. doi: 10.4153/CMB-1968-047-7 . MR 0232743.
1 2 3 4 5 6 7 8 9 10 11 12 Landman, Bruce; Robertson, Aaron; Culver, Clay (2005). "Some New Exact van der Waerden Numbers" (PDF). Integers. 5 (2): A10. MR 2192088.
1 2 3 4 5 6 7 Kouril, Michal (2006). A Backtracking Framework for Beowulf Clusters with an Extension to Multi-Cluster Computation and Sat Benchmark Problem Implementation (Ph.D. thesis). University of Cincinnati.
1 2 Ahmed, Tanbir (2010). "Two new van der Waerden numbers w(2;3,17) and w(2;3,18)". Integers. 10 (4): 369–377. doi:10.1515/integ.2010.032. MR 2684128. S2CID 124272560.
1 2 Ahmed, Tanbir; Kullmann, Oliver; Snevily, Hunter (2014). "On the van der Waerden numbers w(2;3,t)". Discrete Applied Mathematics . 174 (2014): 27–51. arXiv: 1102.5433 . doi: 10.1016/j.dam.2014.05.007 . MR 3215454.
1 2 3 4 Kouril, Michal (2015). "Leveraging FPGA clusters for SAT computations". Parallel Computing: On the Road to Exascale: 525–532.
↑ Beeler, Michael D. (1983). "A new van der Waerden number". Discrete Applied Mathematics . 6 (2): 207. doi: 10.1016/0166-218x(83)90073-2 . MR 0707027.
1 2 3 4 Ahmed, Tanbir (2012). "On computation of exact van der Waerden numbers". Integers. 12 (3): 417–425. doi:10.1515/integ.2011.112. MR 2955523. S2CID 11811448.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Ahmed, Tanbir (2013). "Some More Van der Waerden numbers". Journal of Integer Sequences. 16 (4): 13.4.4. MR 3056628.
1 2 3 4 5 6 7 8 9 10 11 Brown, T. C. (1974). "Some new van der Waerden numbers (preliminary report)". Notices of the American Mathematical Society. 21: A-432.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Ahmed, Tanbir (2009). "Some new van der Waerden numbers and some van der Waerden-type numbers". Integers. 9: A6. doi:10.1515/integ.2009.007. MR 2506138. S2CID 122129059.
↑ Schweitzer, Pascal (2009). Problems of Unknown Complexity, Graph isomorphism and Ramsey theoretic numbers (Ph.D. thesis). U. des Saarlandes.
↑ Shelah, Saharon (1988). "Primitive recursive bounds for van der Waerden numbers". Journal of the American Mathematical Society . 1 (3): 683–697. doi: 10.2307/1990952 . JSTOR 1990952. MR 0929498.

External links

O'Bryant, Kevin & Weisstein, Eric W. "Van der Waerden Number". MathWorld .
Klarreich, Erica (2021-12-15). "Mathematician Hurls Structure and Disorder Into Century-Old Problem". Quanta Magazine .

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[1] Rabung, John; Lotts, Mark (2012). "Improving the use of cyclic zippers in finding lower bounds for van der Waerden numbers". Electron. J. Combin. 19 (2). doi: 10.37236/2363 . MR 2928650.

[chvatal1970-2] 1 2 3 4 5 6 7 8 9 10 11 Chvátal, Vašek (1970). "Some unknown van der Waerden numbers". In Guy, Richard; Hanani, Haim; Sauer, Norbert; et al. (eds.). Combinatorial Structures and Their Applications. New York: Gordon and Breach. pp. 31–33. MR 0266891.

[beeleroneil1979-3] 1 2 3 4 5 6 7 Beeler, Michael D.; O'Neil, Patrick E. (1979). "Some new van der Waerden numbers". Discrete Mathematics . 28 (2): 135–146. doi: 10.1016/0012-365x(79)90090-6 . MR 0546646.

[kouril2012-4] 1 2 3 4 5 6 7 8 Kouril, Michal (2012). "Computing the van der Waerden number W(3,4)=293". Integers. 12: A46. MR 3083419.

[ss1978-5] 1 2 Stevens, Richard S.; Shantaram, R. (1978). "Computer-generated van der Waerden partitions". Mathematics of Computation . 32 (142): 635–636. doi: 10.1090/s0025-5718-1978-0491468-x . MR 0491468.

[heule2017-6] 1 2 Heule, MarijnJ (2017). "Avoiding triples in arithmetic progression" (PDF). Journal of Combinatorics. 8: 391–422.

[kp2006-7] 1 2 Kouril, Michal; Paul, Jerome L. (2008). "The Van der Waerden Number W(2,6) is 1132". Experimental Mathematics . 17 (1): 53–61. doi:10.1080/10586458.2008.10129025. MR 2410115. S2CID 1696473.

[monroe2019-8] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Monroe, Daniel (2019). "New Lower Bounds for van der Waerden Numbers Using Distributed Computing". arXiv: 1603.03301 [math.CO].

[9] Gowers, Timothy (2001). "A new proof of Szemerédi's theorem" (PDF). Geom. Funct. Anal. 11 (3): 465–588. doi:10.1007/s00039-001-0332-9. MR 1844079. S2CID 124324198.

[10] Berlekamp, E. (1968). "A construction for partitions which avoid long arithmetic progressions". Canadian Mathematical Bulletin . 11 (3): 409–414. doi: 10.4153/CMB-1968-047-7 . MR 0232743.

[lrc2005-11] 1 2 3 4 5 6 7 8 9 10 11 12 Landman, Bruce; Robertson, Aaron; Culver, Clay (2005). "Some New Exact van der Waerden Numbers" (PDF). Integers. 5 (2): A10. MR 2192088.

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Van der Waerden number

Contents

Tables of Van der Waerden numbers

See also

Related Research Articles

References

Further reading

External links