Tanbir Ahmed, Ph. D.

Research

PublicationsThesesInteger SequencesReviews
Publications • Back to top
023. A Note on the Rado numbers \(R_k(3,c)\)
Tanbir Ahmed, Robert Malo, Daniel Schaal, Submitted to a journal.
Ramsey Theory on the Integers
022. On the \(3\)-color off-diagonal generalized Schur numbers \(S(3; 2, k_1, k_2)\)
Tanbir Ahmed, Luis Boza, Maria P. Revuelta, and Maria I. Sanz, Submitted to a journal.
Ramsey Theory on the Integers SAT-Solving
021. On the \(3\)-color off-diagonal generalized Schur numbers \(S(3; 2,2,k)\)
Tanbir Ahmed, Luis Boza, Maria P. Revuelta, and Maria I. Sanz, Submitted to a journal.
Ramsey Theory on the Integers SAT-Solving
020. Establishing lower bounds and exact values of the \(2\)-color off-diagonal generalized weak Schur numbers \(WS(2; k_1, k_2)\)
Tanbir Ahmed, Luis Boza, Maria P. Revuelta, and Maria I. Sanz, Submitted to a journal.
Ramsey Theory on the Integers SAT-Solving
019. Lower bounds and exact values of the \(2\)-color off-diagonal generalized weak Schur numbers \(WS(2; k_1, k_2)\) conference
Tanbir Ahmed, Luis Boza, Maria P. Revuelta, and Maria I. Sanz, Procedia Computer Science, 223 (2023), 403-405. XII LAGOS, 2023.
Ramsey Theory on the Integers SAT-Solving
018. Exact values and lower bounds on the \(n\)-color weak Schur numbers for \(n = 2, 3\). journal
Tanbir Ahmed, Luis Boza, Maria P. Revuelta, and Maria I. Sanz, The Ramanujan Journal, 62 (2) (2023), 347-363. , Open access, (2023).
Ramsey Theory on the Integers SAT-Solving
017. Thue-Morse substitution and self similar groups and algebras journal
Laurent Bartholdi, José M. R. Caballero, and Tanbir Ahmed, Algebra and Discrete Mathematics, 34 (1) (2022), 1-14.
Self-Similar Algebra
016. A Family of doubly stochastic matrices involving Chebyshev polynomials. journal
Tanbir Ahmed and José M. R. Caballero, Algebra and Discrete Mathematics, 27 (2) (2019), 155-164. MR3982300.
Self-Similar Algebra
015. Power Sum Polynomials as Relaxed EGZ Polynomials. journal
Tanbir Ahmed, Arie Bialostocki, Thang Pham, and Le Anh Vinh, Integers 19 (2019), A49. MR4017190.
Zero-Sum Ramsey Theory
014. On Generalized Schur Numbers journal
Tanbir Ahmed and Daniel Schaal, Experimental Mathematics, 25 (2) (2016), 213-218. MR3463569. (PDF)
Ramsey Theory on the Integers SAT-Solving
013. On Colouring Integers without t-AP distance sets journal
Tanbir Ahmed, Algebra and Discrete Mathematics, 22 (1) (2016), 1-10. MR3573541. (PDF)
Ramsey Theory on the Integers SAT-Solving
012. On Distance Sets in the Triangular Lattice journal
Tanbir Ahmed and David Wildstrom, Bull. Inst. Combin. Appl. 75 (2015), 118-127. MR3444619. (PDF)
Combinatorial Geometry
011. Remembering Hunter Snevily journal
Tanbir Ahmed, André Kézdy, and Douglas B. West, Bull. Inst. Combin. Appl., 73 (2015), 7-17. MR3331369. (PDF)
Research Memoir
010. On the van der Waerden numbers \(w(2; 3, t)\) journal
Tanbir Ahmed, Oliver Kullmann, and Hunter Snevily, Discrete Applied Mathematics, 174 (2014), 27-51. MR3215454.
Ramsey Theory on the Integers SAT-Solving
--- The paper got a citation in D. E. Knuth's Volume 4, Fascicle 6: Chapter on Satisfiability

--- See Wikipedia entry of Van der Waerden numbers for my contributions in that list
--- Recently (2022), Ben Green in New Lower Bounds for van der Waerden Numbers, disproved the much-speculated conjecture \(w(2; 3, k)=\cal{O}(k^2)\) (originally formulated by Ron Graham in around 2004, and subsequently supported with data by others and ourselves) by constructing a red-blue coloring of \(1,2,\ldots,N\) with no blue arithmetic progression of length 3 and no red arithmetic progression of length \(e^{C(\log N)^{3/4}(\log\log N)^{1/4}}\), and consequently showing that \(w(2; 3, k)\) is bounded from below by \(k^{b(k)}\) where \(b(k) = c\left({\log{k}\over\log\log{k}}\right)^{1/3}\). See Erica Klarreich's Quanta Magazine article Mathematician Hurls Structure and Disorder Into Century-Old Problem.
009. The α-labeling number of comets is 2 journal
Tanbir Ahmed and Hunter Snevily, Bull. Inst. Combin. Appl., 72 (2014), 25-40. (PDF) MR3362514.
Graph Labeling
--- (See Joseph A. Gallian's A Dynamic Survey of Graph Labeling)
008. Sparse Distance Sets in the Triangular Lattice journal
Tanbir Ahmed and Hunter Snevily, Electronic Journal of Combinatorics, 20 (4) (2013), P33. MR3158272.
Combinatorial Geometry
007. Unique Sequences Containing No k-Term Arithmetic Progressions journal
Tanbir Ahmed, Janusz Dybizbański, and Hunter Snevily, Electronic Journal of Combinatorics, 20 (4) (2013), P29. MR3158268.
Combinatorics
006. Some properties of Roller Coaster Permutations journal
Tanbir Ahmed and Hunter Snevily, Bull. Inst. Combin. Appl., 68 (2013), 55-69. (PDF) MR3136863.
Combinatorics
--- (See Biedl et al., Rollercoasters: long sequences without short runs., SIAM J. Discrete Math. 33, No. 2, 845-861 (2019).
--- (See two conjectures in the Open Problems Garden)
--- (See William Adamczak A Note on the Structure of Roller Coaster Permutations, preprint, May 2016)
--- (See William Adamczak, Jacob Boni Roller Coaster Permutations and Partition Numbers, preprint, March 2017)
005. Strict Schur Numbers journal
Tanbir Ahmed, Michael G. Eldredge, Jonathan J. Marler, and Hunter Snevily, Integers, 13 (2013). A22. MR3083484.
Ramsey Theory on the Integers
004. Some more van der Waerden numbers journal
Tanbir Ahmed, Journal of Integer Sequences, 16 (2013), Article 13.4.4. MR3056628.
Ramsey Theory on the Integers SAT-Solving
003. On computation of exact van der Waerden numbers journal
Tanbir Ahmed, Integers, 12 (3) (2012), 417-425. Online version: 11 (2011), A71. MR2955523.
Ramsey Theory on the Integers SAT-Solving
002. Two new van der Waerden numbers: w(2; 3, 17) and w(2; 3, 18) journal
Tanbir Ahmed, Integers, 10 (2010), 369-377, A32. MR2684128.
Ramsey Theory on the Integers SAT-Solving
-- First applied DIVIDE-AND-CONQUER Distributed SAT-Solving to compute these numbers in around 2009.
001. Some new van der Waerden numbers and some van der Waerden-type numbers journal
Tanbir Ahmed, Integers, 9 (2009), 65-76, A06 MR2506138.
Ramsey Theory on the Integers SAT-Solving
--- (See tawSolver 1.0: an efficient implementation of the DPLL Algorithm.)
Theses • Back to top
Some Results in Extremal Combinatorics [PDF]
Ph.D. Thesis, 2013, Concordia University.
Advisor: Prof. Clement Lam
An Implementation of the DPLL Algorithm [PDF]
M. Comp. Sci. Thesis, 2009, Concordia University.
Advisor: Prof. Vašek Chvátal

Integer Sequences • Back to top
Van der Waerden numbers \(w(2; 3, n)\) for \(n \geqslant 3\). Only values for \(n=3,4,\ldots,19\) are known
A171081: 9, 18, 22, 32, 46, 58, 77, 97, 114, 135, 160, 186, 218, 238, 279, 312, 349
Van der Waerden numbers \(w(2; 4, n)\) for \(n \geqslant 4\). Only values for \(n=4,5,\ldots,9\) are known
A007784: 35, 55, 73, 109, 146, 309
Van der Waerden numbers \(w(2; 5, n)\) for \(n \geqslant 5\). Only values for \(n=5,6,7\) are known
A217037: 178, 206, 260
Van der Waerden numbers \(w(3; 3, 3, n)\) for \(n \geqslant 3\). Only values for \(n=3,4,5,6\) are known
A217235: 27, 51, 80, 107
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 3, 3)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217005: 9, 14, 17, 20, 21, 24, 25, 28, 31, 33, 35, 37, 39, 42, 44, 46, 48, 50, 51
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 3, 4)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217058: 18, 21, 25, 29, 33, 36, 40, 42, 45, 48, 52, 55
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 3, 5)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217059: 22, 32, 43, 44, 50, 55, 61, 65, 70
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 3, 6)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217060: 32, 40, 48, 56, 60, 65, 71
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 4, 4)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217007: 35, 40, 53, 54, 56, 66, 67
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 4, 5)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217236: 55, 71, 75, 79
Van der Waerden numbers \(w(j+2; t_0,t_1,...,t_{j-1}, 4, 6)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217237: 73, 83, 93, 101
Van der Waerden numbers \(w(j+3; t_0,t_1,...,t_{j-1}, 3, 3, 3)\) with \(t_0 = t_1 = ... = t_{j-1} = 2\).
A217008: 27, 40, 41, 42, 45, 49, 52

Reviews • Back to top
In Math. Reviews
MR3274878, MR3231981, MR3194752, MR3190574, MR3134264, MR3063975, MR3062784, MR3061011
In Computing Reviews
CR141762, CR141855, CR142155, CR142308, CR142738, CR142894
Referee services
American Mathematical Society (AMS) Mathematics of Computation • Bulletin of the Korean Mathematical Society (KMS) • Discrete Applied Mathematics • Integers • Rocky Mountain Journal of Mathematics • The Ramanujan Journal