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1.
Marco Andreatta Elena Chierici Gianluca Occhetta 《Central European Journal of Mathematics》2004,2(2):272-293
Let X be a Fano variety of dimension n, pseudoindex i
X
and Picard number ρX. A generalization of a conjecture of Mukai says that ρX(i
X
−1)≤n. We prove that the conjecture holds for a variety X of pseudoindex i
X
≥n+3/3 if X admits an unsplit covering family of rational curves; we also prove that this condition is satisfied if ρX> and either X has a fiber type extremal contraction or has not small extremal contractions. Finally we prove that the conjecture holds
if X has dimension five. 相似文献
2.
We consider a version of the A
N
Bethe equation of XXX type and introduce a reporduction procedure constructing new solutions of this equation from a given one. The set of all
solutions obtained from a given one is called a population. We show that a population is isomorphic to the sl
N
+1 flag variety and that the populations are in one-to-one correspondence with intersection points of suitable Schubert cycles
in a Grassmanian variety. We also obtain similar results for the root systems B
N
and C
N
. Populations of B
N
and C
N
type are isomorphic to the flag varieties of C
N
and B
N
types respectively. 相似文献
3.
Given a map f: X→Y and a Nielsen root class, there is a number associated to this root class, which is the minimal number of points among all
root classes which are H-related to the given one for all homotopies H of the map f. We show that for maps between closed surfaces it is possible to deform f such that all the Nielsen root classes have cardinality equal to the minimal number if and only if either N R[f]≤1, or N R[f]>1 and f satisfies the Wecken property. Here N R[f] denotes the Nielsen root number. The condition “f satisfies the Wecken property is known to be equivalent to |deg(f)|≤N R[f]/(1−χ(M
2)−χ(M
10/(1−χ(M
2)) for maps between closed orientable surfaces. In the case of nonorientable surfaces the condition is A(f)≤N R[f]/(1−χ(M
2)−χ(M
2)/(1−χ(M
2)). Also we construct, for each integer n≥3, an example of a map f: K
n
→N from an n-dimensionally connected complex of dimension n to an n-dimensional manifold such that we cannot deform f in a way that all the Nielsen root classes reach the minimal number of points at the same time. 相似文献
4.
Li Wenxia 《数学学报(英文版)》1998,14(4):487-494
Corresponding to the irreducible 0–1 matrix (a
ij
)
n×n
, take similitude contraction mappingsϕ
ij
for eacha
ij
=1, ina
ij
=1, in R
d
with ratio 0<r
ij
<1. There are unique nonempty compact setsF
1,…,F
n
satisfying for each1≤i≤n, F
i. We prove that open set condition holds if and only ifF
i
is ans-set for some1≤i≤n, wheres is such that the spectral radius of matrix (r
ij
3
)
n x n
is 1.
Partly supported by Natural Science Foundation of China, and partly by Natural Science Foundation of Hubei Province 相似文献
5.
Associated with the L
p
-curvature image defined by Lutwak, some inequalities for extended mixed p-affine surface areas of convex bodies and the support functions of L
p
-projection bodies are established. As a natural extension of a result due to Lutwak, an L
p
-type affine isoperimetric inequality, whose special cases are L
p
-Busemann-Petty centroid inequality and L
p
-affine projection inequality, respectively, is established. Some L
p
-mixed volume inequalities involving L
p
-projection bodies are also established. 相似文献
6.
Let Top
0
be the category of topological T
0-spaces, QU
0
the category of quasi-uniform T
0-spaces, T : QU
0
→ Top
0
the usual forgetful functor and K : QU
0
→ QU
0
the bicompletion reflector with unit k : 1 → K. Any T-section F : Top
0
→ QU
0
is called K-true if KF = FTKF, and upper (lower)
K-true if KF is finer (coarser) than FTKF. The literature considers important T-sections F that enjoy all three, or just one, or none of these properties. It is known that T(K,k)F is well-pointed if and only if F is upper K-true. We prove the surprising fact that T(K,k)F is the reflection to Fix(TkF) whenever it is idempotent. We also prove a new characterization of upper K-trueness. We construct examples to set apart some natural cases. In particular we present an upper K-true F for which T(K,k)F is not idempotent, and a K-true F for which the coarsest associated T-preserving coreflector in QU
0
is not stable under K.
We dedicate this paper to the memory of Sérgio de Ornelas Salbany (1941–2005). 相似文献
7.
Florentina Chirte§ 《Central European Journal of Mathematics》2005,3(1):105-124
The aim of this paper is to define the localization LM
n
-algebra of an LM
n
—algebra L with respect to a topology F on L; in Section 5 we prove that the maximal LM
n
-algebra of fractions (defined in [3]) and the LM
n
-algebra of fractions relative to an Λ—closed system (defined in Section 2) are LM
n
-algebras of localization. 相似文献
8.
Anders Kock 《Central European Journal of Mathematics》2004,2(5):708-724
We describe for any Riemannian manifold M a certain scheme M
L
, lying in between the first and second neighbourhood of the diagonal of M. Semi-conformal maps between Riemannian manifolds are then analyzed as those maps that preserve M
L
; harmonic maps are analyzed as those that preserve the (Levi-Civita-) mirror image formation inside M
L
. 相似文献
9.
J. L. Hayden 《Designs, Codes and Cryptography》1997,12(1):69-73
The paper studies a generalized Hadamard matrix H = (g
i
j) of order n with entries gi
j from a group G of order n. We assume that H satisfies: (i) For m k, G = {g
m
i
g
k
i
-1 i = 1,...., n} (ii) g
1i = g
i1 = 1 for each i; (iii) g
ij
-1 = g
ji for all i, j. Conditions (i) and (ii) occur whenever G is a(P, L) -transitivity for a projective plane of order n. Condition (iii) holds in the case that H affords a symmetric incidence matrix for the plane. The paper proves that G must be a 2-group and extends previous work to the case that n is a square. 相似文献
10.
ChangJian Zhao 《中国科学A辑(英文版)》2008,51(12):2172-2188
In this paper the author first introduce a new concept of L
p
-dual mixed volumes of star bodies which extends the classical dual mixed volumes. Moreover, we extend the notions of L
p
intersection body to L
p
-mixed intersection body. Inequalities for L
p
-dual mixed volumes of L
p
-mixed intersection bodies are established and the results established here provide new estimates for these type of inequalities.
This work was supported by the Natural Science Foundation of Zhejiang Province of China (Grant No. Y605065) and the Foundation
of the Education Department of Zhejiang Province of China (Grant No. 20050392) 相似文献
11.
Anm-consecutive-k-out-of-n:F system is a system ofn linearly arranged components which fails if and only if at leastm non-overlapping sequences ofk components fail, when there arek distinct components with failure probabilitiesq
i
fori=1,...,k and where the failure probability of thej-th component (j=rk+i (1 ≤i ≤k) isq
j
=q
i
, we call this system by anm-consecutive-k-out-of-n:F system with cycle (or period)k. In this paper we give a formula of the failure probability ofm-consecutive-k-out-of-n:F system with cyclek via the failure probability of consecutive-k-out-of-n:F system. 相似文献
12.
The class of γn-complete hypergroups is introduced. Several properties and examples are found both of γn-complete hypergroups and of KH hypergroups. 相似文献
13.
Kebin Li Shouguo Wang Rongsheng Cheng Xijun Li Denglu Hou Xiangfu Nie Yuheng Zhang 《中国科学A辑(英文版)》1999,42(7):758-762
The ferromagnetic transition temperatures have been measured on two bathes of perovskite manganese oxides such as (La1-x
R
x
)2/3Ca1/3MnO3(R=Ce, Pr, Nd, etc.) and La2/3(Ca1-y
Cd
y
)1/3MnO3. It is found that the (La1-x
R
x
)2/3Ca1/3MnO3 samples have obviously different Curie temperatureT
C
although their (rA) (the average A-site cation radius) are almost identical, and theT
C
in the system of (La1-x
R
x
)2/3Ca1/3MnO3(R=Ce, Pr, Nd, etc.) and La2/3(Ca1-y
Cd
y
)1/3MnO3. It is found that the (La1-x
R
x
)2/3Ca1/3MnO3 compounds increases with increasingy although (rA) decreases slightly. It is suggested that the Curie temperature should be influenced by the average local A-site magnetic
moment in the ferromagnetic perovskite manganite system.
Project supported by the National Natural Science Foundation of China (Grant No. 19504012) and the Chinese Academy of Sciences. 相似文献
14.
Marc Levine 《K-Theory》1992,6(2):113-175
LetR be a commutative, semi-local ring,I
1, ...,I
s
ideals. In this paper, we define therelative Milnor K-groups of (R;I
1, ...,I
s
),K
p
M
(R;I
1, ...,I
s
), and show that these groups have many of the properties of the usual MilnorK-groups of a field. In particular, assuming a weak condition on the ideals, we show thatK
p
M
(R;I
1, ...,I
s
) is isomorphic to the weightp portion of the relative QuillenK-groupK
p
(R;I
1, ...,I
s
), after inverting (p–1)!. We also define the relative group homology of GL
n
(R;I
1, ...,I
s
), and show thatK
p
M
(R;I
1, ...,I
s
) is isomorphic toH
p
(GLp(R;I
1, ...,I
s
))/Im(H
p
(GL
p–1 (R;I
1, ...,I
s
))). Finally, we consider a generalization to the relative setting of Kato's conjecture asserting that the Galois symbol gives an isomorphism fromK
p
M
(F)/l
v
to
, and show that this relative version of Kato's conjecture implies the Quillen-Lichtenbaum conjectures asserting the Chern class:
相似文献
15.
Daniel Lehmann 《Annals of Global Analysis and Geometry》1994,12(1):109-122
LetX
1 andX
2 be two holomorphic vector fields on a manifoldV with complex dimensionp. Assume that they have the same singular set . For all
, it is known (after Chern-Bott) that each of the vector fields defines a residual characteristic classC
1(V,X
1)(resp.C
1(V,X
2)) inH
2p
(V, V-), which is a lift of the usual characteristic classC
1
(V) of the tangent bundle. The differenceC
1
(V,X
2)-C
1
(V,X
1) belongs then to the image of in the exact sequence. In fact, there exists a canonical liftC
1
(V,X
1,X
2) of this difference inH
2p–1(V-): we will call itthe residual class of order 2 (associated toI, X
1 andX
2). This class is localized near the points whereX
1 andX
2 are colinear: we will explain this precisely in terms of Grothendieck residues. The formula that we obtain can be interpreted as a generalization of the purely algebraic identity, obtained from the general one as a byproduct: where (
1, , p) and (
1,,
p
) denote two families of non-zero complex numbers, such that all denominators in this formula do not vanish. (This identity corresponds in fact to the case whereX
1 andX
2 are non-degenerate at the same isolated singular point.)If the
i
's (1ip) depend now differentiably (resp. holomorphically) on a real (resp. complex) parametert then, denoting by the derivative with respect tot, and assuming all numbers lying in a denominator not to be 0, we can deduce from the above identity the following derivation formula: 相似文献
16.
M. R. Salehirad A. Badamchizadeh 《Central European Journal of Operations Research》2009,17(2):131-139
In this paper we consider an M/G/1 queue with k phases of heterogeneous services and random feedback, where the arrival is Poisson and service times has general
distribution. After the completion of the i-th phase, with probability θ
i
the (i + 1)-th phase starts, with probability p
i
the customer feedback to the tail of the queue and with probability 1 − θ
i
− p
i
= q
i
departs the system if service be successful, for i = 1, 2 , . . . , k. Finally in kth phase with probability p
k
feedback to the tail of the queue and with probability 1 − p
k
departs the system. We derive the steady-state equations, and PGF’s of the system is obtained. By using them the mean queue
size at departure epoch is obtained. 相似文献
17.
Let X1,...,Xn be independent and identically distributed random variables and Wn = Wn(X1,...,Xn) be an estimator of parameter θ.Denote Tn =(Wn - θ0)/sn,where sn2 is a variance estimator of Wn.In this paper a general result on the limiting distributions of the non-central studen-tized statistic Tn is given.Especially,when s2n is the jacknife estimate of variance,it is shown that the limit could be normal,a weighted χ2 distribution,a stable distribution,or a mixture of normal and stable distribution.Applicati... 相似文献
18.
Roger Bielawski 《Annals of Global Analysis and Geometry》1996,14(2):123-145
We prove a recent conjecture of Manton and Murray: if a polynomialp(z) of degreek — 1 is given, then anSU (2) monopole corresponding to a rational functionp(z)/q(z) with well-separated poles \1,...,\k is approximately made up from charge 1 monopoles located at points (1/2 In p(\i), \i). We show how the rate of approximation changes with the numeratorp(z) with the result that, as long as the values of the numerator remain close together relative to the distances between poles, the above statement remains true and ceases to be so otherwise.We also show that the spectral curve of the monopole approaches the union of curves of charge 1 monopoles exponentially fast. This remains true forSU (N) monopoles. 相似文献
19.
Volker Krtschmer 《Fuzzy Sets and Systems》2002,130(3):1064
The classes of the Lp,∞- and Lp-metrics play an important role to develop a probability theory in fuzzy sample spaces. All of these metrics are known to be separable, but not complete. The classes are closely related as for each Lp,∞-metric there exists some Lp-metric which induces the same topology. This paper deals with the completion of the Lp,∞- and Lp-metrics. We can also show that the relationship between the classes of Lp,∞- and Lp-metrics still holds for the obtained respective classes of their completions. 相似文献
20.
Meng-xiao Yin 《应用数学学报(英文版)》2006,22(3):451-456
Let a(Kr,+1 - K3,n) be the smallest even integer such that each n-term graphic sequence п= (d1,d2,…dn) with term sum σ(п) = d1 + d2 +…+ dn 〉 σ(Kr+1 -K3,n) has a realization containing Kr+1 - K3 as a subgraph, where Kr+1 -K3 is a graph obtained from a complete graph Kr+1 by deleting three edges which form a triangle. In this paper, we determine the value σ(Kr+1 - K3,n) for r ≥ 3 and n ≥ 3r+ 5. 相似文献
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