Bounds on the kissing number



Let k(n) denote the kissing number in n dimensions, i.e., the maximal
number of hyperspheres of radius 1 that can touch a given hypersphere
of radius 1 without any overlapping. I am interested in bounds on a =
lim k(n)^(1/n), but the information I have managed to find on the net
is somewhat limited.

The page http://cherrypit.princeton.edu/sphd/ mentions a lower bound
2^0.2075... which is probably (?) a re-writing of 2 / sqrt(3). I have
not seen any upper bounds.

Numerical evidence might suggest a = something near sqrt(2); the
formula 2n (2^(n/2) - 1) actually gives the exact kissing number for
the exceptional cases n = 8 and n = 24, but it is not quite right for
n = 2 and 3. (And I am not overly excited about its apparent
correctness for n = 4 since an arrangement of 24 hyperspheres around a
given one leaves a lot of "extra room".) However, I have a heuristic
argument that indeed points towards an upper bound of sqrt(2) for a.
Is this an already proven upper bound?

Thanks in advance.

---
J K Haugland
http://home.no.net/zamunda
.



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