共查询到20条相似文献,搜索用时 25 毫秒
1.
Yong-Kum Cho Sunggeum Hong Joonil Kim Chan Woo Yang 《Integral Equations and Operator Theory》2009,65(4):485-528
Given
W ì \mathbbZ+3\Omega \subset {\mathbb{Z}}_{+}^{3}, we discuss a necessary and sufficient condition that the triple Hilbert transform associated with any polynomial of the
form ($t_1, t_2, t_3,\sum_{m
\in \Omega} a_{m} t^m$t_1, t_2, t_3,\sum_{m
\in \Omega} a_{m} t^m) is bounded in
Lp(\mathbbR4)L^p({\mathbb{R}}^4). 相似文献
2.
Extending a result of Meyer and Reisner (Monatsh Math 125:219–227, 1998), we prove that if
g: \mathbbR? \mathbbR+{g: \mathbb{R}\to \mathbb{R}_+} is a function which is concave on its support, then for every m > 0 and every
z ? \mathbbR{z\in\mathbb{R}} such that g(z) > 0, one has
ò\mathbbR g(x)mdxò\mathbbR (g*z(y))m dy 3 \frac(m+2)m+2(m+1)m+3, \int\limits_{\mathbb{R}} g(x)^mdx\int\limits_{\mathbb{R}} (g^{*z}(y))^m dy\ge \frac{(m+2)^{m+2}}{(m+1)^{m+3}}, 相似文献
3.
We study hypersurfaces in the Lorentz-Minkowski space
\mathbbLn+1{\mathbb{L}^{n+1}} whose position vector ψ satisfies the condition L
k
ψ = Aψ + b, where L
k
is the linearized operator of the (k + 1)th mean curvature of the hypersurface for a fixed k = 0, . . . , n − 1,
A ? \mathbbR(n+1)×(n+1){A\in\mathbb{R}^{(n+1)\times(n+1)}} is a constant matrix and
b ? \mathbbLn+1{b\in\mathbb{L}^{n+1}} is a constant vector. For every k, we prove that the only hypersurfaces satisfying that condition are hypersurfaces with zero (k + 1)th mean curvature, open pieces of totally umbilical hypersurfaces
\mathbbSn1(r){\mathbb{S}^n_1(r)} or
\mathbbHn(-r){\mathbb{H}^n(-r)}, and open pieces of generalized cylinders
\mathbbSm1(r)×\mathbbRn-m{\mathbb{S}^m_1(r)\times\mathbb{R}^{n-m}},
\mathbbHm(-r)×\mathbbRn-m{\mathbb{H}^m(-r)\times\mathbb{R}^{n-m}}, with k + 1 ≤ m ≤ n − 1, or
\mathbbLm×\mathbbSn-m(r){\mathbb{L}^m\times\mathbb{S}^{n-m}(r)}, with k + 1 ≤ n − m ≤ n − 1. This completely extends to the Lorentz-Minkowski space a previous classification for hypersurfaces in
\mathbbRn+1{\mathbb{R}^{n+1}} given by Alías and Gürbüz (Geom. Dedicata 121:113–127, 2006). 相似文献
4.
Palash Sarkar 《Designs, Codes and Cryptography》2011,58(3):271-278
Let
\mathbbF{\mathbb{F}} be a finite field and suppose that a single element of
\mathbbF{\mathbb{F}} is used as an authenticator (or tag). Further, suppose that any message consists of at most L elements of
\mathbbF{\mathbb{F}}. For this setting, usual polynomial based universal hashing achieves a collision bound of
(L-1)/|\mathbbF|{(L-1)/|\mathbb{F}|} using a single element of
\mathbbF{\mathbb{F}} as the key. The well-known multi-linear hashing achieves a collision bound of
1/|\mathbbF|{1/|\mathbb{F}|} using L elements of
\mathbbF{\mathbb{F}} as the key. In this work, we present a new universal hash function which achieves a collision bound of
mélogm Lù/|\mathbbF|, m 3 2{m\lceil\log_m L\rceil/|\mathbb{F}|, m\geq 2}, using 1+élogm Lù{1+\lceil\log_m L\rceil} elements of
\mathbbF{\mathbb{F}} as the key. This provides a new trade-off between key size and collision probability for universal hash functions. 相似文献
5.
We study the limiting behavior of the K?hler–Ricci flow on
\mathbbP(O\mathbbPn ?O\mathbbPn(-1)?(m+1)){{\mathbb{P}(\mathcal{O}_{\mathbb{P}^n} \oplus \mathcal{O}_{\mathbb{P}^n}(-1)^{\oplus(m+1)})}} for m, n ≥ 1, assuming the initial metric satisfies the Calabi symmetry. We show that the flow either shrinks to a point, collapses
to
\mathbbPn{{\mathbb{P}^n}} or contracts a subvariety of codimension m + 1 in the Gromov–Hausdorff sense. We also show that the K?hler–Ricci flow resolves a certain type of cone singularities
in the Gromov–Hausdorff sense. 相似文献
6.
Andrea Bonfiglioli 《Archiv der Mathematik》2009,93(3):277-286
Let ${\mathbb{G}}
7.
T. Schoen 《Archiv der Mathematik》2002,79(3):171-174
Let S \subseteqq \mathbbZm S \subseteqq \mathbb{Z}_m be a Sidon set of cardinality | S | = m1/2 + O(1) \mid S \mid = m^{1 \over 2} + O(1) . It is proved, in particular, that for any interval á = {a, a + 1, ?, a + l- 1} {\cal I} = \{a, a + 1, \ldots, a + \ell - 1\} in \mathbbZm \mathbb{Z}_m , 0 \leqq l 0 \leqq \ell < m, we have | | S ?á | - | S | l/m | = O( | S | 1/2ln m) \big| {\mid S \cap {\cal I} \mid - \mid S \mid \ell/m} \big| = O(\mid S \mid^{1 \over 2}\textrm{ln}\, m) . 相似文献
8.
Let
C( \mathbbRm ) C\left( {{\mathbb{R}^m}} \right) be the space of bounded and continuous functions
x:\mathbbRm ? \mathbbR x:{\mathbb{R}^m} \to \mathbb{R} equipped with the norm
|