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2-Cancellative Hypergraphs and Codes

Published online by Cambridge University Press:  02 February 2012

ZOLTÁN FÜREDI*
Affiliation:
Department of Mathematics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA and Rényi Institute of Mathematics of the Hungarian Academy of Sciences, Budapest, PO Box 127, Hungary-1364 (e-mail: z-furedi@illinois.edu, furedi@renyi.hu)

Abstract

A family of sets (and the corresponding family of 0–1 vectors) is called t-cancellative if, for all distinct t + 2 members A1,. . ., At and B, C, Let ct(n) be the size of the largest t-cancellative family on n elements, and let ct(n, r) denote the largest r-uniform family. We improve the previous upper bounds, e.g., we show c2(n) ≤ 20.322n (for n > n0). Using an algebraic construction we show that c2(n, 2k) = Θ(nk) for each k when n → ∞.

Type
Paper
Copyright
Copyright © Cambridge University Press 2012

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