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Propeller Conjecture


The propeller conjecture asserts that three planar sectors of angle 2pi/3 maximize the sum of squared Gaussian first moments over measurable partitions, after extension in orthogonal directions. Precisely, if gamma_d is the standard Gaussian measure on R^d, the proposed bound for a set partition (A_1,...,A_k) into measurable sets is

 sum_(i=1)^k||int_(A_i)xdgamma_d(x)||^2<=9/(8pi).

The first moments are unnormalized vectors, and the norms are Euclidean. Cell probabilities are unrestricted, and empty cells are allowed. For d>=2 and k>=3, the three sectors, multiplied by their orthogonal complement, attain 9/(8pi), with any remaining cells empty.


See also

Gaussian Measure, Normal Distribution, Set Partition

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References

Heilman, S.; Jagannath, A.; and Naor, A. "Solution of the Propeller Conjecture in R^3." Disc. Comput. Geom. 50, 263-305, 2013. https://doi.org/10.1007/s00454-013-9530-0.

Cite this as:

Weisstein, Eric W. "Propeller Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/PropellerConjecture.html

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