Abstract: | R. B. Kusner [R. Guy, Amer. Math. Monthly 90, 196-199 (1983)]asked whether a set of vectors in such that the distance between any pair is 1, has cardinality at mostd + 1.We show that this is true for p = 4and any , and false for all 1d sufficiently large, depending on p. Moregenerally we show that the maximum cardinality is at most if p is an even integer, and at least if 1 depends on p.Received: 5 May 2003 |