共查询到20条相似文献,搜索用时 15 毫秒
1.
Meirav Amram Ciro Ciliberto Rick Miranda Mina Teicher 《Israel Journal of Mathematics》2009,170(1):61-93
In this paper we consider a non-prime K3 surface of degree 16, and study a specific degeneration of it, known as the (2, 2)-pillow degeneration, [10].
We study also the braid monodromy factorization of the branch curve of the surface with respect to a generic projection onto
ℂℙ2.
In [4], we compute the fundamental groups of the complement of the branch curve and of the corresponding Galois cover of the
surface.
Partially supported by the DAAD fellowship (Germany), the Golda Meir post-doctoral fellowship (the Einstein Mathematics Institute,
Hebrew University, Jerusalem), the Emmy Noether Research Institute for Mathematics (center of the Minerva Foundation of Germany),
the Excellency Center “Group Theoretic Methods in the Study of Algebraic Varieties” of the Israel Science Foundation, and
EAGER (EU network, HPRN-CT-2009-00099). 相似文献
2.
Given a projective surface and a generic projection to the plane,the braid monodromy factorization(and thus,the braid monodromy type)of the complement of its branch curve is one of the most important topological invariants,stable on deformations.From this factorization,one can compute the fundamental group of the complement of the branch curve,either in C~2 or in CP~2.In this article,we show that these groups,for the Hirzebruch surface F_1,(a,b),are almost-solvable.That is, they are an extension of a solvable group,which strengthen the conjecture on degeneratable surfaces. 相似文献
3.
4.
We give an upper bound for the first Dirichlet eigenvalue of a tube around a complex curve P of ℂP
n
(λ) which depends only on the radius of the tube and the degrees of the polynomials defining P. The bound is sharp on a totally geodesic ℂP
1(λ) and gives a gap between the eigenvalue of a tube around ℂP
1(λ) and around other complex curves. 相似文献
5.
A. L. Shydlich 《Ukrainian Mathematical Journal》2008,60(6):950-966
We consider the problem of saturation of the linear methods of summation of Fourier series in the spaces S
p
φ specified by arbitrary sequences of functions defined in a certain subset of the space ℂ. Sufficient conditions for the saturation
of the indicated methods in these spaces are established.
Translated from Ukrains'kyi Matematychnyi Zhurnal, Vol. 60, No. 6, pp. 815–828, June, 2008. 相似文献
6.
We prove that if the existence of a supercompact cardinal is consistent with ZFC, then it is consistent with ZFC that the
p-rank of Ext
ℤ(G, ℤ) is as large as possible for every prime p and for any torsion-free Abelian group G. Moreover, given an uncountable
strong limit cardinal μ of countable cofinality and a partition of Π (the set of primes) into two disjoint subsets Π0 and Π1, we show that in some model which is very close to ZFC, there is an almost free Abelian group G of size 2μ = μ+ such that the p-rank of Ext
ℤ(G, ℤ) equals 2μ = μ+ for every p ∈ Π0 and 0 otherwise, that is, for p ∈ Π1.
Number 874 in Shelah’s list of publications. Supported by the German-Israeli Foundation for Scientific Research & Development
project No. I-706-54.6/2001.
Supported by a grant from the German Research Foundation DFG.
__________
Translated from Algebra i Logika, Vol. 46, No. 3, pp. 369–397, May–June, 2007. 相似文献
7.
Francesca Vetro 《manuscripta mathematica》2008,125(3):353-368
Let Y be a smooth, connected, projective complex curve. In this paper, we study the Hurwitz spaces which parameterize branched
coverings of Y whose monodromy group is a Weyl group of type D
d
and whose local monodromies are all reflections except one. We prove the irreducibility of these spaces when and successively we extend the result to curves of genus g ≥ 1. 相似文献
8.
Xiao Yun CHENG Jian Guo XIA Hou Rong QIN 《数学学报(英文版)》2007,23(5):819-826
Let K2 be the Milnor functor and let Фn (x)∈ Q[X] be the n-th cyclotomic polynomial. Let Gn(Q) denote a subset consisting of elements of the form {a, Фn(a)}, where a ∈ Q^* and {, } denotes the Steinberg symbol in K2Q. J. Browkin proved that Gn(Q) is a subgroup of K2Q if n = 1,2, 3, 4 or 6 and conjectured that Gn(Q) is not a group for any other values of n. This conjecture was confirmed for n =2^T 3S or n = p^r, where p ≥ 5 is a prime number such that h(Q(ζp)) is not divisible by p. In this paper we confirm the conjecture for some n, where n is not of the above forms, more precisely, for n = 15, 21,33, 35, 60 or 105. 相似文献
9.
László Verhóczki 《Monatshefte für Mathematik》2004,141(4):323-335
In the present paper we discuss in detail the cohomogeneity one isometric actions of the Lie groups SU(3) × SU(3) and SU(3) on the exceptional compact symmetric spaces G2 and G2/SO(4), respectively. We show that the principal orbits coincide with the tubular hypersurfaces around the totally geodesic singular orbits, and the symmetric spaces G2 and G2/SO(4) can be thought of as compact tubes around SU(3) and P2, respectively. Moreover, we determine the radii of these tubes and describe the shape operators of the principal orbits. Finally, we apply these results to compute the volumes of the two symmetric spaces.The author was partially supported by the Hungarian National Science and Research Foundation OTKA T032478. 相似文献
10.
The paper gives some characterization theorems for the compact composition operator on some function spaces over the unit
ball B
n
in ℂ
n
. Especially, it gives a characterization for compact composition operators on BMOA(B
n
), which generalizes a result proved by Bourdon, Cima and Matheson for the case n = 1. 相似文献
11.
Let ℳ be a von Neumann factor of type II1 with a normalized trace τ. In 1983 L. G. Brown showed that to every operator T∈ℳ one can in a natural way associate a spectral distribution measure
μ
T (now called the Brown measure of T), which is a probability measure in ℂ with support in the spectrum σ(T) of T. In this paper it is shown that for every T∈ℳ and every Borel set B in ℂ, there is a unique closed T-invariant subspace
affiliated with ℳ, such that the Brown measure of
is concentrated on B and the Brown measure of
is concentrated on ℂ∖B. Moreover,
is T-hyperinvariant and the trace of
is equal to μ
T(B). In particular, if T∈ℳ has a Brown measure which is not concentrated on a singleton, then there exists a non-trivial, closed,
T-hyperinvariant subspace. Furthermore, it is shown that for every T∈ℳ the limit
exists in the strong operator topology, and the projection onto
is equal to 1[0,r](A), for every r>0.
Supported by The Danish National Research Foundation. 相似文献
12.
DuanLiqin LiCuixiang 《分析论及其应用》2004,20(3):242-251
In this paper,we will use the 2r-th Ditzian-Totik modulus of smoothness wp^2r(f,t)p to discuss the direct and inverse theorem of approximation by Left-Bernstein-Durrmeyer quasi-interpolants Mn^[2r-1]f for functions of the space Lp[0,1](1≤p≤ ∞)。 相似文献
13.
In this paper, we investigate a generalization of graph decomposition, called hypergraph decomposition. We show that a decomposition of a 3-uniform hypergraph K(3)v into a special kind of hypergraph K(3)4 - e exists if and only if v ≡ 0, 1, 2 (mod 9) and v ≥ 9. 相似文献
14.
In this paper we investigate a certain linear combination K([(x)\vec])=K(a;b,c,d;e,f,g)K(\vec{x})=K(a;b,c,d;e,f,g) of two Saalschutzian hypergeometric series of type 4
F
3(1). We first show that K([(x)\vec])K(\vec{x}) is invariant under the action of a certain matrix group G
K
, isomorphic to the symmetric group S
6, acting on the affine hyperplane V={(a,b,c,d,e,f,g)∈ℂ7:e+f+g−a−b−c−d=1}. We further develop an algebra of three-term relations for K(a;b,c,d;e,f,g). We show that, for any three elements μ
1,μ
2,μ
3 of a certain matrix group M
K
, isomorphic to the Coxeter group W(D
6) (of order 23040) and containing the above group G
K
, there is a relation among K(m1[(x)\vec])K(\mu_{1}\vec{x}), K(m2[(x)\vec])K(\mu_{2}\vec{x}), and K(m3[(x)\vec])K(\mu_{3}\vec{x}), provided that no two of the μ
j
’s are in the same right coset of G
K
in M
K
. The coefficients in these three-term relations are seen to be rational combinations of gamma and sine functions in a,b,c,d,e,f,g. 相似文献
15.
V. Alexandru N. Popescu M. Vâjâitu A. Zaharescu 《Proceedings Mathematical Sciences》2010,120(1):45-55
Given a prime number p and the Galois orbit O(x) of a normal element x of ℂ
p
, the topological completion of the algebraic closure of the field of p-adic numbers, we study the Iwasawa algebra of O(x) with scalars drawn from ℚ
p
and relate it with ℚ
p
-distributions and functionals. 相似文献
16.
Von Neumann-Jordan Constants of Absolute Normalized Norms on C^n 总被引:1,自引:0,他引:1
In this note, we give some estimations of the Von Neumann-Jordan constant C
N J
(∥·∥ψ) of Banach space (ℂ
n
, ∥·∥ψ), where ∥·∥ψ is the absolute normalized norm on ℂ
n
given by function ψ. In the case where ψ and φ are comparable, n=2 and C
N J
(∥·∥ψ)=1, we obtain a formula of computing C
N J
(∥·∥ψ). Our results generalize some results due to Saito and others.
Received May 11, 2002, Accepted November 20, 2002
This work is partly supported by NNSF of China (No. 19771056) 相似文献
17.
S. É. Derkachev 《Theoretical and Mathematical Physics》2011,169(2):1539-1550
We show a connection between the R-matrix factorization, the Baxter Q-operator, and separation of variables in the example
of an integrable spin chain with the SL(2, ℂ) symmetry group. 相似文献
18.
Motivated by the problem of Hurwitz equivalence of Δ2 factorization in the braid group, we address the problem of Hurwitz equivalence in the symmetric group, of 1s
n
factorizations with transposition factors. Looking at the transpositions as the edges in a graph, we show that two factorizations
are Hurwitz equivalent if and only if their graphs have the same weighted connected components. The graph structure allows
us to compute Hurwitz equivalence in the symmetric group. Using this result, one can compute non-Hurwitz equivalence in the
braid group.
This paper is part of the author’s PhD thesis.
This work was partially supported by the Emmy Noether Research Institute for Mathematics (center of the Minerva Foundation
of Germany), the Excellency Center “Group Theoretic Methods in the Study of Algebraic Varieties” of the Israel Science Foundation,
and by EAGER (EU network, HPRN-CT-2009-00099). Received December 31, 2001 and in revised form August 6, 2002 相似文献
19.
Let F n be the free group of rank n, and let Aut+(F n ) be its special automorphism group. For an epimorphism π : F n → G of the free group F n onto a finite group G we call the standard congruence subgroup of Aut+(F n ) associated to G and π. In the case n = 2 we fully describe the abelianization of Γ+(G, π) for finite abelian groups G. Moreover, we show that if G is a finite non-perfect group, then Γ+(G, π) ≤ Aut+(F 2) has infinite abelianization. 相似文献
20.
We construct examples of exponentially asymptotically cylindrical (EAC) Riemannian 7-manifolds with holonomy group equal to
G
2. To our knowledge, these are the first such examples. We also obtain EAC coassociative calibrated submanifolds. Finally,
we apply our results to show that one of the compact G
2-manifolds constructed by Joyce by desingularisation of a flat orbifold T
7/Γ can be deformed to give one of the compact G
2-manifolds obtainable as a generalized connected sum of two EAC SU(3)-manifolds via the method of Kovalev (J Reine Angew Math 565:125–160, 2003). 相似文献