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Burnside Problem


The Burnside problem originated with Burnside (1902), who wrote, "A still undecided point in the theory of discontinuous groups is whether the group order of a group may be not finite, while the order of every operation it contains is finite." This question would now be phrased, "Can a finitely generated group be infinite while every group element has finite order?" (Vaughan-Lee 1993). This question was answered by Golod (1964) when he constructed finitely generated infinite p-groups. These groups, however, do not have a finite group exponent.

Let r and n be positive integers, let F_r be the free group on r group generators, and let N be the normal subgroup of F_r generated by all nth powers g^n with g in F_r. The quotient group B(r,n)=F_r/N is the r-generator Burnside group of group exponent n. Every group generated by at most r elements whose group exponent divides n is the image of B(r,n) under a surjective group homomorphism. The bounded-exponent Burnside problem asks for which r and n the group B(r,n) is a finite group.

An answer is known for the following values. For r=1, B(1,n) is a cyclic group of group order n. For n=1, B(r,1) is the trivial group. For n=2, B(r,2) is an elementary Abelian group of group order 2^r. For n=3, B(r,3) was proved to be finite by Burnside (1902). The group order of the B(r,3) groups was established by Levi and van der Waerden (1933), namely 3^a where

 a=r+(r; 2)+(r; 3).
(1)

Here (r; k) is a binomial coefficient. For n=4, B(r,4) was proved to be finite by Sanov (1940). For groups of exponent four, the precise nilpotency class and derived length are known, as are bounds for the group order. The known exact group orders for B(r,4) at r=1, 2, ..., 5 are summarized in the following table. The first few values for r=1, 2, ... are 4, 4096, 590295810358705651712, ... (OEIS A079682), corresponding to 2 to the powers 2, 12, 69, 422, 2728, ... (OEIS A116398).

r|B(r,4)|reference
12^2
22^(12)Tobin (1954)
32^(69)Bayes et al. (1974)
42^(422)Havas and Newman (1980)
52^(2728)Newman and O'Brien (1996)

The inequality |B(2,4)|<=2^(12) was proved by Burnside (1902), who also claimed equality. The result |B(3,4)|=2^(69) was proved with help from a computer after the inequality |B(3,4)|<=2^(69) had been obtained "by hand" by Gupta and Newman (1974).

For larger values of r the exact value is not yet known. For n=6, B(r,6) was proved to be finite by Hall (1957, 1958) with group order 2^a3^(b+(b; 2)+(b; 3)), where

a=1+(r-1)3^c
(2)
b=1+(r-1)2^r
(3)
c=r+(r; 2)+(r; 3).
(4)

These results give positive solutions for every finite number of group generators at group exponents 1, 2, 3, 4, and 6. For r>=2 and odd n>=4381, Novikov and Adjan (1968) proved that B(r,n) is infinite. Adian later reduced the threshold to odd n>=665 (Ivanov 1998, p. 67). Lysenok (1996) proved that B(r,n) is infinite for r>=2 and even n>=8000.

The restricted Burnside problem asks whether the group orders of all finite groups generated by at most r elements with group exponent dividing n have a bound depending only on r and n. The answer is affirmative (Vaughan-Lee 1993). E. Zelmanov was awarded a Fields medal in 1994 for his solution (International Mathematical Union 1994).


See also

Finitely Presented Group, Free Group, Group Exponent, Group Order, Normal Closure

Portions of this entry contributed by Beata Bajorska

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References

Bayes, A. J.; Kautsky, J.; and Wamsley, J. W. "Computation in Nilpotent Groups (Application)." In Proceedings of the Second International Conference on the Theory of Groups. Held at the Australian National University, Canberra, August 13-24, 1973 (Ed. M. F. Newman). New York: Springer-Verlag, pp. 82-89, 1974.Burnside, W. "On an Unsettled Question in the Theory of Discontinuous Groups." Quart. J. Pure Appl. Math. 33, 230-238, 1902.Golod, E. S. "On Nil-Algebras and Residually Finite p-Groups." Isv. Akad. Nauk SSSR Ser. Mat. 28, 273-276, 1964.Gupta, N. D. and Newman, M. F. "The Nilpotency Class of Finitely Generated Groups of Exponent Four." In Proceedings of the Second International Conference on the Theory of Groups. Held at the Australian National University, Canberra, August 13-24, 1973 (Ed. M. F. Newman). New York: Springer-Verlag, pp. 330-332, 1974.Hall, M. Jr. "Solution of the Burnside Problem for Exponent 6." Proc. Natl. Acad. Sci. USA 43, 751-753, 1957. https://doi.org/10.1073/pnas.43.8.751.Hall, M. "Solution of the Burnside Problem for Exponent Six." Ill. J. Math. 2, 764-786, 1958. https://doi.org/10.1215/ijm/1255448339.Havas, G. and Newman, M. F. "Application of Computers to Questions like Those of Burnside." In Burnside Groups. Proceedings of a Workshop Held at the University of Bielefeld, Bielefeld, June-July 1977. New York: Springer-Verlag, pp. 211-230, 1980.International Mathematical Union. "Fields Medals 1994." https://www.mathunion.org/imu-awards/fields-medal/fields-medals-1994.Ivanov, S. V. "On the Burnside Problem for Groups of Even Exponent." Doc. Math. Extra Volume ICM 1998, II, 67-75, 1998. https://ems.press/content/book-chapter-files/27136.Levi, F. and van der Waerden, B. L. "Über eine besondere Klasse von Gruppen." Abh. Math. Sem. Univ. Hamburg 9, 154-158, 1933.Lysenok, I. G. "Infinite Burnside Groups of Even Exponent." Izv. Math. 60, 453-654, 1996. https://doi.org/10.1070/IM1996v060n03ABEH000077.Newman, M. F. and O'Brien, E. A. "Application of Computers to Questions like Those of Burnside, II." Internat. J. Algebra Comput. 6, 593-605, 1996. https://doi.org/10.1142/S0218196796000337.Novikov, P. S. and Adjan, S. I. "Infinite Periodic Groups I, II, III." Izv. Akad. Nauk SSSR Ser. Mat. 32, 212-244, 251-524, and 709-731, 1968.Sanov, I. N. "Solution of Burnside's Problem for Exponent Four." Leningrad State Univ. Ann. Math. Ser. 10, 166-170, 1940.Sloane, N. J. A. Sequences A079682 and A116398 in "The On-Line Encyclopedia of Integer Sequences."Tobin, J. J. "On Groups with Exponent 4." Thesis. Manchester, England: University of Manchester, 1954.Vaughan-Lee, M. The Restricted Burnside Problem, 2nd ed. New York: Clarendon Press, 1993.

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Burnside Problem

Cite this as:

Weisstein, Eric W., with contributions by Beata Bajorska. "Burnside Problem." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BurnsideProblem.html

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