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Irreducibility and Galois groups of truncated binomial polynomials. (English) Zbl 07872254

Summary: For positive integers \(n \geq m\), let \(P_{n, m}(x) := \sum_{j = 0}^{m} \binom{n}{j} x^{j} = \binom{n}{0} + \binom{n}{1}x + \dots + \binom{n}{m}x^{m}\) be the truncated binomial expansion of \((1 + x)^{n}\) consisting of all terms of degree \(\leq m\). It is conjectured that for \(n > m + 1\), the polynomial \(P_{n, m}(x)\) is irreducible. We confirm this conjecture when \(2m \leq n < (m + 1)^{10}\). Also we show for any \(r \geq 10\) and \(2m \leq n < (m + 1)^{r + 1}\), the polynomial \(P_{n, m}(x)\) is irreducible when \(m \geq \max\{10^{6}, 2r^{3}\}\). Under the explicit abc-conjecture, for a fixed \(m\), we give an explicit \(n_{0}\), \(n_{1}\) depending only on \(m\) such that \(\forall n \geq n_{0}\), the polynomial \(P_{n, m}(x)\) is irreducible. Further \(\forall n \geq n_{1}\), the Galois group associated to \(P_{n, m}(x)\) is the symmetric group \(S_{m}\).

MSC:

11R32 Galois theory
11R09 Polynomials (irreducibility, etc.)
Full Text: DOI

References:

[1] Baker, A., Experiments on the abc-conjecture, Publ. Math. Debrecen65 (2004) 253-260. · Zbl 1064.11050
[2] Borisov, A., Filaseta, M., Lam, T. Y. and Trifonov, O., Classes of polynomials having only one non-cyclotomic irreducible factor, Acta Arith.90 (1999) 121-153. · Zbl 0935.11039
[3] Dubickas, A. and Šiurys, J., Some irreducibility and indecomposability results for truncated binomial polynomials of small degree, Proc. Indian Acad. Sci. Math. Sci.127 (2017) 45-57. · Zbl 1405.12001
[4] Dumas, G., Sur quelques cas d’irréductibilité des polynômes á coefficients rationnels, J. Math. Pure Appl.2 (1906) 191-258. · JFM 37.0096.01
[5] P. Dusart, Autour de la fonction qui compte le nombre de nombres premiers, Ph.D thesis, Université de Limoges (1998).
[6] Filaseta, M., Kumchev, A. and Pasechnik, D., On the irreducibility of a truncated binomial expansion, Rocky Mt. J. Math.37 (2007) 455-464. · Zbl 1211.12004
[7] Filaseta, M. and Moy, R., On the Galois group over \(\Bbb Q\) of a truncated binomial expansion, Colloq. Math.154 (2018) 295-308. · Zbl 1446.11193
[8] Hajir, F., On the Galois group of generalized Laguerre polynomials, J. Théor. Nombres Bordeaux17 (2005) 517-525. · Zbl 1094.11042
[9] Jakhar, A. and Sangwan, N., Some results for the irreducibility of truncated binomial expansions, J. Number Theory192 (2018) 143-149. · Zbl 1448.11065
[10] Khanduja, S. K., Khassa, R. and Laishram, S., Some irreducibility results for truncated binomial expansions, J. Number Theory131(2) (2011) 300-308. · Zbl 1213.11185
[11] Klahn, B. and Technau, M., Galois groups of \(\left(\substack{ n \\ 0}\right)+\left(\substack{ n \\ 1}\right)X+\ldots+\left(\substack{ n \\ 6}\right) X^6\), Int. J. Number Theory19 (2023) 2443-2450. · Zbl 1536.11173
[12] Laishram, S. and Shorey, T. N., Baker’s explicit abc-conjecture and applications, Acta Arith.155 (2012) 419-429. · Zbl 1276.11048
[13] Laishram, S. and Shorey, T. N., The equation \(n(n+d)\cdots(n+(k-1)d)=b y^2\) with \(\omega(d)\leq6\) or \(d\leq1 0^{1 0}\), Acta Arith.129 (2007) 249-305. · Zbl 1140.11020
[14] Lehmer, D. H., On a problem of Störmer, Illinois J. Math.8(1) (1964) 57-79. · Zbl 0124.27202
[15] Luca, F. and Najman, F., On the largest prime factor of \(x^2-1\), Math. Comput.80 (2011) 429-435. · Zbl 1221.11080
[16] Mukhopadhyay, A. and Shorey, T. N., Square free part of products of consecutive integers, Publ. Math. Debrecen64 (2004) 79-99. · Zbl 1049.11037
[17] Saradha, N. and Shorey, T. N., Almost squares and factorisations in consecutive integers, Compos. Math.138 (2003) 113-124. · Zbl 1038.11020
[18] I. Scherbak, Intersections of schubert varieties and highest weight vectors in tensor products \(s l_{N + 1}\)- representations, preprint (2005), arXiv:math.RT/0409329.
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