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Cyclic Sieving Phenomenon


Let a cyclic group C=<rho> of group order N act on a finite set X, and let f(q)=sum_(x in X)q^(stat(x)) be a generating polynomial for a statistic on X. The triple (X,C,f(q)) exhibits the cyclic sieving phenomenon if, for every divisor d of N and every primitive dth root of unity omega,

 f(omega)=#{x in X:rho^(N/d)x=x}.

Thus evaluations of f(q) at roots of unity count the fixed points of corresponding elements of the group action (Reiner et al. 2004).

Armstrong (2026) studied multisets of fixed cardinality whose elements have multiplicity less than a bound b. When a cyclic group acts by rotating the underlying labels, the associated bounded q-binomial coefficient gives cyclic sieving whenever the relevant rotation order is relatively prime to b. This simultaneously generalizes the cases of subsets and unrestricted multisets. Specializing at certain roots of unity also connects these polynomials with the two-denomination coin problem.


See also

Coin Problem, Fixed Point, Generating Function, Group Action, Root of Unity, Tableau Promotion, q-Binomial Coefficient

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References

Armstrong, D. "Cyclic Sieving of Multisets with Bounded Multiplicity and the Frobenius Coin Problem." Elec. J. Combin. 33, No. 3, P3.40, 1-35, 2026. https://doi.org/10.37236/15255.Reiner, V.; Stanton, D.; and White, D. "The Cyclic Sieving Phenomenon." J. Combin. Th., Ser. A 108, 17-50, 2004.

Cite this as:

Weisstein, Eric W. "Cyclic Sieving Phenomenon." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CyclicSievingPhenomenon.html

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