The Flatness Theorem for Nonsymmetric Convex Bodies Via the Local Theory of Banach Spaces

  • Authors:
  • Wojciech Banaszczyk;Alexander E. Litvak;Alain Pajor;Stanislaw J. Szarek

  • Affiliations:
  • -;-;-;-

  • Venue:
  • Mathematics of Operations Research
  • Year:
  • 1999

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Abstract

Let L be a lattice in Rn and K a convex body disjoint from L. The classical Flatness Theorem asserts that then w(K, L), the L-width of K, does not exceed some bound, depending only on the dimension n; this fact was later found relevant to questions in integer programming. Kannan and Lovasz (1988) showed that under the above assumptions w(K, L) ≤ Cn2, where C is a universal constant. Banaszczyk (1996) proved that w(K, L) ≤ Cn(1 + log n) if K has a centre of symmetry. In the present paper we show that w(K, L) ≤ Cn3/2 for an arbitrary K. It is conjectured that the exponent 3/2 may be replaced by 1, perhaps at the cost of a logarithmic factor; we prove that for some naturally arising classes of bodies.