On the continuation to bent functions and upper bounds on their number
A Boolean bent function / of n variables is a continuation of a Boolean function g of k < n variables if g is a restriction of / to a fixed affine plane of dimension k. We prove that a continuation always exists if k ^ n/2. We obtain an upper bound for the number of continuations. The bound is strengthened in the case k = n - 1, when g is a near-bent function. As a result, we improve the known upper bounds for the number of bent functions. More precisely, we show that for even n ^ 6 there are no more than Cn 2,-2-„,2+5/2 (B(nAn - 2)-f- 1n - 1) + B(n/2 - 1, n - 1)) bent functions of n variables. Here cn = exp(-1/2 + 23/(18 · 2n-2))/y/n and B(d, n) = = 2(II)+(II)+...+(II).
Keywords
бент-функция,
число бент-функций,
почти-бент-функция,
аффинная плоскость,
bent function,
number of bent functions,
near-bent function,
affine planeAuthors
Agievich S. V. | Belarusian State University | agievich@bsu.by |
Всего: 1
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