Casas-Alvero conjecture

In mathematics, the Casas-Alvero conjecture is an open problem about polynomials which have factors in common with their derivatives, proposed by Eduardo Casas-Alvero in 2001.
Formal statement
Let f be a polynomial of degree d defined over a field K of characteristic zero. If f has a factor in common with each of its derivatives f(i), i = 1, ..., d − 1, then the conjecture predicts that f must be a power of a linear polynomial.
Analogue in non-zero characteristic
The conjecture is false over a field of characteristic p: any inseparable polynomial f(Xp) without constant term satisfies the condition since all derivatives are zero. Another, separable, counterexample is Xp+1 − Xp
Special cases
The conjecture is known to hold in characteristic zero for degrees of the form pk or 2pk where p is prime and k is a positive integer. Similarly, it is known for degrees of the form 3pk where p ≠ 2, for degrees of the form 4pk where p ≠ 3, 5, 7, and for degrees of the form 5pk where p ≠ 2, 3, 7, 11, 131, 193, 599, 3541, 8009. Similar results are available for degrees of the form 6pk and 7pk. It has recently been established for d = 12, making d = 20 the smallest open degree.
References
- Casas-Alvero, Eduardo (2001). "Higher order polar germs". J. Algebra 240 (1): 326–337. doi:10.1006/jabr.2000.8727. ISSN 0021-8693.
- Diaz-Toca, Gema M.; Gonzalez-Vega, Laureano (2006). "On analyzing a conjecture about univariate polynomials and their roots by using Maple". in Kotsireas, Ilias. Maple conference 2006. Proceedings of the conference, Waterloo, Ontario, Canada, July 23–26, 2006. Waterloo: Maplesoft. pp. 81–98. ISBN 1-897310-13-7.
- Graf von Bothmer, Hans-Christian; Labs, Oliver; Schicho, Josef; van de Woestijne, Christiaan (2007). "The Casas-Alvero conjecture for infinitely many degrees". J. Algebra 316 (1): 224–230. doi:10.1016/j.jalgebra.2007.06.017.
- Draisma, Jan; de Jong, Johan P. (2011). "On the Casas-Alvero conjecture". Eur. Math. Soc. Newsl. 80: 29–33. ISSN 1027-488X. Archived from the original on 2016-03-04. https://web.archive.org/web/20160304090949/http://www.ems-ph.org/journals/newsletter/pdf/2011-06-80.pdf.
- Castryck, Wouter; Laterveer, Robert; Ounaïes, Myriam (2012). "Constraints on counterexamples to the Casas-Alvero conjecture, and a verification in degree 12". arXiv:1208.5404 [math.AG].
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