共查询到20条相似文献,搜索用时 31 毫秒
1.
The symmetric group $\operatorname{Sym}(d)$ acts on the Cartesian product (S 2) d by coordinate permutation, and the quotient space $(S^{2})^{d}/\operatorname{Sym}(d)$ is homeomorphic to the complex projective space ?P d . We used the case d=2 of this fact to construct a 10-vertex triangulation of ?P 2 earlier. In this paper, we have constructed a 124-vertex simplicial subdivision $(S^{2})^{3}_{124}$ of the 64-vertex standard cellulation $(S^{2}_{4})^{3}$ of (S 2)3, such that the $\operatorname{Sym}(3)$ -action on this cellulation naturally extends to an action on $(S^{2})^{3}_{124}$ . Further, the $\operatorname{Sym}(3)$ -action on $(S^{2})^{3}_{124}$ is ??good??, so that the quotient simplicial complex $(S^{2})^{3}_{124}/\operatorname{Sym}(3)$ is a 30-vertex triangulation $\mathbb{C}P^{3}_{30}$ of ?P 3. In other words, we have constructed a simplicial realization $(S^{2})^{3}_{124} \to\mathbb{C} P^{3}_{30}$ of the branched covering (S 2)3???P 3. 相似文献
2.
Romain Tessera 《Positivity》2012,16(4):633-640
We study the L p -distortion of finite quotients of amenable groups. In particular, for every ${2\leq p < \infty}$ , we prove that the ? p -distortions of the groups ${C_2\wr C_n}$ and ${C_{2^n}\rtimes C_n}$ are in ${\Theta((\log n)^{1/p}),}$ and that the ? p -distortion of ${C_n^2 \rtimes_A \mathbf{Z}}$ , where A is the matrix ${{\left({\small\begin{array}{cc}2 & 1 \\ 1 & 1 \end{array}} \right)}}$ is in ${\Theta((\log \log n)^{1/p}).}$ 相似文献
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4.
Abdelmalek Azizi Abdelkader Zekhnini Mohammed Taous 《Czechoslovak Mathematical Journal》2014,64(1):11-29
Let p 1 ≡ p 2 ≡ 1 (mod 8) be primes such that \(\left( {\tfrac{{p_1 }} {{p_2 }}} \right) = - 1\) and \(\left( {\tfrac{2} {{a + b}}} \right) = - 1\) , where p 1 p 2 = a 2+b 2. Let \(i = \sqrt { - 1} \) , d = p 1 p 2, \(\Bbbk = \mathbb{Q}(\sqrt {d,} i),\Bbbk _2^{(1)} \) be the Hilbert 2-class field and \(\Bbbk ^{(*)} = \mathbb{Q}(\sqrt {p_1 } ,\sqrt {p_2 } ,i)\) be the genus field of \(\Bbbk \) . The 2-part \(C_{\Bbbk ,2} \) of the class group of \(\Bbbk \) is of type (2, 2, 2), so \(\Bbbk _2^{(1)} \) contains seven unramified quadratic extensions \(\mathbb{K}_j /\Bbbk \) and seven unramified biquadratic extensions \(\mathbb{L}_j /\Bbbk \) . Our goal is to determine the fourteen extensions, the group \(C_{\Bbbk ,2} \) and to study the capitulation problem of the 2-classes of \(\Bbbk \) . 相似文献
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Let M n be a closed Riemannian manifold of diameter d. Our first main result is that for every two (not necessarily distinct) points ${p,q \in M^n}$ and every positive integer k there are at least k distinct geodesics connecting p and q of length ${\leq 4nk^2d}$ . We demonstrate that all homotopy classes of M n can be represented by spheres swept-out by “short” loops unless the length functional has “many” “deep” local minima of a “small” length on the space ${\Omega_{pq}M^n}$ of paths connecting p and q. For example, one of our results implies that for every positive integer k there are two possibilities: Either the length functional on ${\Omega_{pq} M^n}$ has k distinct non-trivial local minima with length ${\leq 2kd}$ and “depth” ${\geq 2d}$ ; or for every m every map of S m into ${\Omega_{pq}M^n}$ is homotopic to a map of S m into the subspace ${\Omega_{pq}^{4(k+2)(m+1)d}M^n}$ of ${\Omega_{pq}M^n}$ that consists of all paths of length ${\leq 4(k+2)(m+1)d}$ . 相似文献
7.
Janusz Morawiec 《Aequationes Mathematicae》2014,88(1-2):175-181
We determine nontrivial intervals \({I \subset(0,+\infty)}\) , numbers \({\alpha\in\mathbb R}\) and continuous bijections \({f \colon I \to I}\) such that f(x)f ?1(x) = x α for every \({x\in I}\) . 相似文献
8.
We show that if f: M 3 → M 3 is an A diffeomorphism with a surface two-dimensional attractor or repeller $\mathcal{B}$ with support $M_\mathcal{B}^2$ , then $\mathcal{B} = M_\mathcal{B}^2$ and there exists a k ≥ 1 such that (1) $M_\mathcal{B}^2$ is the disjoint union M 1 2 ? ? ? M k 2 of tame surfaces such that each surface M i 2 is homeomorphic to the 2-torus T 2; (2) the restriction of f k to M i 2 , i ∈ {1,..., k}, is conjugate to an Anosov diffeomorphism of the torus T 2. 相似文献
9.
Holland et al. (Algebra Univers 67:1–18, 2012) considered varieties ${\mathcal E}_n$ of lattice-ordered groups defined by partial metrics, and showed for all n that ${\mathcal E}_n$ is contained within the variety ${\mathcal L}_n$ defined by x n y n ?=?y n x n . They also showed that if n were prime, then ${\mathcal E}_n = {\mathcal L}_n$ . Letting ${\mathcal A}^2$ denote the metabelian variety (defined at the beginning of Section 2), this article continues their work, showing that for all n, ${\mathcal L}_n \cap {\mathcal A}^2 \subseteq {\mathcal E}_n$ while showing that if n is not prime, ${\mathcal L}_n \not\subseteq {\mathcal E}_n$ . 相似文献
10.
Benjamin Sambale 《Algebras and Representation Theory》2013,16(6):1717-1732
We determine the numerical invariants of blocks with defect group $Q_{2^n}\times C_{2^m}$ and $SD_{2^n}\times C_{2^m}$ , where $Q_{2^n}$ denotes a quaternion group of order 2 n , $C_{2^m}$ denotes a cyclic group of order 2 m , and $SD_{2^n}$ denotes a semidihedral group of order 2 n . This generalizes Olsson’s results for m?=?0. As a consequence, we prove Brauer’s k(B)-Conjecture, Olsson’s Conjecture, Brauer’s Height-Zero Conjecture, the Alperin–McKay Conjecture, Alperin’s Weight Conjecture and Robinson’s Ordinary Weight Conjecture for these blocks. Moreover, we show that the gluing problem has a unique solution in this case. This paper follows (and uses) (Sambale, J Pure Appl Algebra 216:119–125, 2012; Proc Amer Math Soc, 2012). 相似文献
11.
In this paper, a general orthogonal transformation on the optimal quaternary sequence Families ${\mathcal{B}}$ and ${\mathcal{C}}$ is presented. Consequently, the known optimal Family ${\mathcal{D}}$ and a new optimal Family ${\mathcal{E}}$ are produced in a uniform method. In contrast to the known optimal Family ${\mathcal{D}}$ , the new Family ${\mathcal{E}}$ has the same parameters such as the sequence length 2(2 n ? 1), the family size 2 n , and the maximal nontrivial correlation value ${2^{\frac{n+1}{2}}+2}$ , where n is a positive integer, but with a different correlation function. 相似文献
12.
G. D. Allen 《Results in Mathematics》1988,14(3-4):211-222
Let \(\bar x\) , \(\bar y\ \in\ R_n\) be vectors which satisfy x1 ≥ x2 ≥ … ≥ xn and y1 ≥ y2 >- … ≥ yn and Σxi = Σyi. We say that \(\bar x\) is power majorized by \(\bar y\) if Σxi p ≤ Σyi p for all real p ? [0, 1] and Σxi p ≥ Σyi p for p ∈ [0, 1]. In this paper we give a classification of functions ? (which includes all possible positive polynomials) for which \(\bar\phi(\bar x) \leq \bar\phi(\bar y)\) (see definition below) when \(\bar x\) is power majorized \(\bar y\) . We also answer a question posed by Clausing by showing that there are vectors \(\bar x\) , \(\bar y\ \in\ R^n\) of any dimension n ≥ 4 for which there is a convex function ? such that \(\bar x\) is power majorized by \(\bar y\) and \(\bar\phi(\bar x)\ >\ \bar\phi(\bar y)\) . 相似文献
13.
We prove that the $2n + 1$ -dimensional Heisenberg group H n and the 4-manifolds $Nil^4 $ and $Nil^3 \times \mathbb{R}$ endowed with an arbitrary left-invariant metric admit no C 3-regular immersions into Euclidean spaces $\mathbb{R}^{2n + 2} $ and $\mathbb{R}^5 $ , respectively. 相似文献
14.
Lothar Heinrich Michaela Prokešová 《Methodology and Computing in Applied Probability》2010,12(3):451-471
We investigate a class of kernel estimators $\widehat{\sigma}^2_n$ of the asymptotic variance σ 2 of a d-dimensional stationary point process $\Psi = \sum_{i\ge 1}\delta_{X_i}$ which can be observed in a cubic sampling window $W_n = [-n,n]^d\,$ . σ 2 is defined by the asymptotic relation $Var(\Psi(W_n)) \sim \sigma^2 \,(2n)^d$ (as n →? ∞) and its existence is guaranteed whenever the corresponding reduced covariance measure $\gamma^{(2)}_{red}(\cdot)$ has finite total variation. Depending on the rate of decay (polynomially or exponentially) of the total variation of $\gamma^{(2)}_{red}(\cdot)$ outside of an expanding ball centered at the origin, we determine optimal bandwidths b n (up to a constant) minimizing the mean squared error of $\widehat{\sigma}^2_n$ . The case when $\gamma^{(2)}_{red}(\cdot)$ has bounded support is of particular interest. Further we suggest an isotropised estimator $\widetilde{\sigma}^2_n$ suitable for motion-invariant point processes and compare its properties with $\widehat{\sigma}^2_n$ . Our theoretical results are illustrated and supported by a simulation study which compares the (relative) mean squared errors of $\widehat{\sigma}^2_n$ for planar Poisson, Poisson cluster, and hard-core point processes and for various values of n b n . 相似文献
15.
In the present study, we consider isometric immersions ${f : M \rightarrow \tilde{M}(c)}$ of (2n + 1)-dimensional invariant submanifold M 2n+1 of (2m + 1) dimensional Sasakian space form ${\tilde{M}^{2m+1}}$ of constant ${ \varphi}$ -sectional curvature c. We have shown that if f satisfies the curvature condition ${\overset{\_}{R}(X, Y) \cdot \sigma =Q(g, \sigma)}$ then either M 2n+1 is totally geodesic, or ${||\sigma||^{2}=\frac{1}{3}(2c+n(c+1)),}$ or ${||\sigma||^{2}(x) > \frac{1}{3}(2c+n(c+1)}$ at some point x of M 2n+1. We also prove that ${\overset{\_ }{R}(X, Y)\cdot \sigma = \frac{1}{2n}Q(S, \sigma)}$ then either M 2n+1 is totally geodesic, or ${||\sigma||^{2}=-\frac{2}{3}(\frac{1}{2n}\tau -\frac{1}{2}(n+2)(c+3)+3)}$ , or ${||\sigma||^{2}(x) > -\frac{2}{3}(\frac{1}{2n} \tau (x)-\frac{1}{2} (n+2)(c+3)+3)}$ at some point x of M 2n+1. 相似文献
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In recent years, functional codes have received much attention. In his PhD thesis, F.A.B. Edoukou investigated various functional codes linked to quadrics and Hermitian varieties defined in finite projective spaces (Edoukou, PhD Thesis, 2007). This work was continued in (Edoukou et al., Des Codes Cryptogr 56:219–233, 2010; Edoukou et al., J Pure Appl Algebr 214:1729–1739, 2010; Hallez and Storme, Finite Fields Appl 16:27–35, 2010), where the results of the thesis were improved and extended. In particular, Hallez and Storme investigated the functional codes ${C_2(\mathcal{H})}$ , with ${\mathcal{H}}$ a non-singular Hermitian variety in PG(N, q 2). The codewords of this code are defined by evaluating the points of ${\mathcal{H}}$ in the quadratic polynomials defined over ${\mathbb{F}_{q^2}}$ . We now present the similar results for the functional code ${C_{Herm}(\mathcal{Q})}$ . The codewords of this code are defined by evaluating the points of a non-singular quadric ${\mathcal{Q}}$ in PG(N, q 2) in the polynomials defining the Hermitian varieties of PG(N, q 2). 相似文献
18.
Jaume Gin�� Jaume Llibre 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,62(4):567-574
In this paper, we prove that the C 1 planar differential systems that are integrable and non-Hamiltonian roughly speaking are C 1 equivalent to the linear differential systems ${\dot u= u}$ , ${\dot v= v}$ . Additionally, we show that these systems have always a Lie symmetry. These results are improved for the class of polynomial differential systems defined in ${\mathbb{R}^2}$ or ${\mathbb{C}^2}$ . 相似文献
19.
Krzysztof Bogdan Tomasz Komorowski 《NoDEA : Nonlinear Differential Equations and Applications》2014,21(4):541-566
We study the principal Dirichlet eigenvalue of the operator \({L_A=\Delta^{\alpha/2}+Ab(x)\cdot\nabla}\) , on a bounded C 1,1 regular domain D. Here \({\alpha\in(1,2)}\) , \({\Delta^{\alpha/2}}\) is the fractional Laplacian, \({A\in\mathbb{R}}\) , and b is a bounded d-dimensional divergence-free vector field in the Sobolev space W 1,2d/(d+α)(D). We prove that the eigenvalue remains bounded, as A→ + ∞, if and only if b has non-trivial first integrals in the domain of the quadratic form of \({\Delta^{\alpha/2}}\) for the Dirichlet condition. 相似文献
20.
It is conjectured that the set ${\mathcal {G}}$ of the primitive roots modulo p has no decomposition (modulo p) of the form ${\mathcal {G}= \mathcal {A} +\mathcal {B}}$ with ${|\mathcal {A}|\ge 2}$ , ${|\mathcal {B} |\ge 2}$ . This conjecture seems to be beyond reach but it is shown that if such a decomposition of ${\mathcal {G}}$ exists at all, then ${|\mathcal {A} |}$ , ${|\mathcal {B} |}$ must be around p 1/2, and then this result is applied to show that ${\mathcal {G}}$ has no decomposition of the form ${\mathcal {G} =\mathcal {A} + \mathcal {B} + \mathcal {C}}$ with ${|\mathcal {A} |\ge 2}$ , ${|\mathcal {B} |\ge 2}$ , ${|\mathcal {C} |\ge 2}$ . 相似文献