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New dense superball packings in three dimensions

  • Maria Dostert and Frank Vallentin EMAIL logo
Published/Copyright: October 8, 2020
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Abstract

We construct a new family of lattice packings for superballs in three dimensions (unit balls for the l3p norm) with p ∈ (1, 1.58]. We conjecture that the family also exists for p ∈ (1.58, log2 3 = 1.5849625…]. Like in the densest lattice packing of regular octahedra, each superball in our family of lattice packings has 14 neighbors.

MSC 2010: 11H31; 52C17; 90C30

Award Identifier / Grant number: DMS-1439786

Funding statement: This material is based upon work supported by the National Science Foundation under Grant No. DMS-1439786 while the first author was in residence at the Institute for Computational and Experimental Research in Mathematics in Providence, RI, during the “Point Configurations in Geometry, Physics and Computer Science” semester program. The second author was partially supported by the SFB/TRR 191 “Symplectic Structures in Geometry, Algebra and Dynamics”, funded by the DFG. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie agreement number 764759.

Acknowledgements

We thank Cristóbal Guzmán and Philippe Moustrou for helpful discussions. We thank the referee for useful suggestions and corrections.

  1. Communicated by: M. Henk

A Source code for the proof of Theorem 4.2

We used the following program written in Sage in the proof of Theorem 4.2.

def f(p,x,y,z):

return vector([x^p+y^p+z^p-1, (x–y)^p+(z–x)^p+(y+z)^p–1, 3*(–x+y+z)^p–1])

def Df(p,x,y,z):

pm = p–1

return p*Matrix([[x^pm, y^pm, z^pm],

[(x–y)^pm–(z–x)^pm, –(x–y)^pm+(y+z)^pm, (z–x)^pm+(y+z)^pm],

[–3*(–x+y+z)^pm, 3*(–x+y+z)^pm, 3*(–x+y+z)^pm]])

def linfinitynorm(A):

return max([A.row(0).norm(1),A.row(1).norm(1),A.row(2).norm(1)])

def verify(p0,x0,y0,z0,eps,peps):

p = RIF(p0,p0+peps)

x = RIF(x0-eps,x0+eps)

y = RIF(y0-eps,y0+eps)

z = RIF(z0-eps,z0+eps)

T = Df(p0,x0,y0,z0)^(–1)

A = Df(p,x,y,z)*T – identity_matrix(3)

lhs = linfinitynorm(A)

rhs = 1 – linfinitynorm(T)*f(p,x0,y0,z0).norm(infinity)/eps

print(lhs.str(style=’brackets’)+’<’+rhs.str(style=’brackets’)+’:’+str(lhs < rhs))

B Examples of choices made in the proof of Theorem 4.2

verify(1.0, 0.333333333333, 0.166666666667, 0.5, 0.03, 0.01)

verify(1.01, 0.336543320255, 0.169227330456, 0.504294897412, 0.03, 0.01)

verify(1.02, 0.339721855623, 0.171809715243, 0.508503843298, 0.03, 0.01)

verify(1.5, 0.475292821919, 0.375983627555, 0.580059051165, 0.03, 0.01)

verify(1.51, 0.47822053429, 0.384961182567, 0.576346694842, 0.03, 0.01)

verify(1.52, 0.481163698665, 0.394556223383, 0.572012690078, 0.006, 0.001)

verify(1.521, 0.48145875646, 0.395553814361, 0.571540873724, 0.006, 0.001)

verify(1.522, 0.481753934423, 0.396558835694, 0.571061553436, 0.006, 0.001)

verify(1.523, 0.482049228267, 0.39757142775, 0.570574584849, 0.006, 0.001)

verify(1.577, 0.497880292399, 0.472696125604, 0.523437325276, 0.006, 0.001)

verify(1.578, 0.498157887988, 0.475000219764, 0.521630841401, 0.006, 0.001)

verify(1.579, 0.498433446144, 0.477421354522, 0.519705097786, 0.006, 0.001)

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Received: 2018-07-01
Published Online: 2020-10-08
Published in Print: 2020-10-27

© 2020 Walter de Gruyter GmbH, Berlin/Boston

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