共查询到20条相似文献,搜索用时 484 毫秒
1.
F. A. Sukochev 《Integral Equations and Operator Theory》1996,26(1):102-124
If is a surjective isometry of the separable symmetric operator spaceE(M, ) associated with the approximately finite-dimensional semifinite factorM and if ·
E(M,)
is not proportional to ·
L
2, then there exist a unitary operatorUM and a Jordan automorphismJ ofM such that(x)=UJ(x) for allxME(M, ). We characterize also surjective isometries of vector-valued symmetric spacesF((0, 1), E(M, )).Research supported by the Australian Research Council 相似文献
2.
A family of sequences has the Ramsey property if for every positive integerk, there exists a least positive integerf
(k) such that for every 2-coloring of {1,2, ...,f
(k)} there is a monochromatick-term member of . For fixed integersm > 1 and 0 q < m, let q(m) be the collection of those increasing sequences of positive integers {x
1,..., xk} such thatx
i+1 – xi q(modm) for 1 i k – 1. Fort a fixed positive integer, denote byA
t
the collection of those arithmetic progressions having constant differencet. Landman and Long showed that for allm 2 and 1 q < m,
q(m) does not have the Ramsey property, while
q(m)
A
m
does. We extend these results to various finite unions of
q(m)
's andA
t
's. We show that for allm 2,
q=1
m–1
q(m) does not have the Ramsey property. We give necessary and sufficient conditions for collections of the form
q(m)
(
t T
A
t) to have the Ramsey property. We determine when collections of the form a(m1) b(m2) have the Ramsey property. We extend this to the study of arbitrary finite unions of q(m)'s. In all cases considered for which has the Ramsey property, upper bounds are given forf
. 相似文献
3.
Douglas A. Leonard 《Designs, Codes and Cryptography》1991,1(2):183-189
Any nonsingular linear transformation : GF(qs) GF(qs) can be used to treat a linear cyclic code of wordlength v over GF(qs) as a linear code () of Wordlength sv over GF(q). This paper determines those linear cyclic codes and transformations for which the resulting linear code () is also cyclic. 相似文献
4.
5.
For a bounded regular Jordan domain in R
2, we introduce and study a new class of functions K() related on its Green function G. We exploit the properties of this class to prove the existence and the uniqueness of a positive solution for the singular nonlinear elliptic equation u+(x,u)=0, in D(), with u=0 on and uC(), where is a nonnegative Borel measurable function in ×(0,) that belongs to a convex cone which contains, in particular, all functions (x,t)=q(x)t
–,>0 with nonnegative functions qK(). Some estimates on the solution are also given. 相似文献
6.
Klaus-Jürgen Eckardt 《manuscripta mathematica》1976,18(1):43-55
The problem of existence of wave operators for the Klein-Gordon equation (
t
2
–+2+iV1t+V2)u(x,t)=0 (x R
n,t R, n3, >0) is studied where V1 and V2 are symmetric operators in L2(R
n) and it is shown that conditions similar to those of Veseli-Weidmann (Journal Functional Analysis 17, 61–77 (1974)) for a different class of operators are also sufficient for the Klein-Gordon equation. 相似文献
7.
A. B. Aleksandrov 《Journal of Mathematical Sciences》1993,63(2):115-129
Let be an inner function, let C, ¦¦=1. Then the harmonic function [(+)]/(–)] is the Poisson integral of a singular measure
D. N. Clark's known theorem enables us to identify in a natural manner the space H2 H2 with the space L2
(
).Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 170, pp. 7–33, 1989. 相似文献
8.
Xiang-Dong Hou 《Designs, Codes and Cryptography》1992,2(3):215-224
Let R(r, m) be the rth order Reed-Muller code of length 2
m
, and let (r, m) be its covering radius. We prove that if 2 k m - r - 1, then (r + k, m + k) (r, m + 2(k - 1). We also prove that if m - r 4, 2 k m - r - 1, and R(r, m) has a coset with minimal weight (r, m) which does not contain any vector of weight (r, m) + 2, then (r + k, m + k) (r, m) + 2k(. These inequalities improve repeated use of the known result (r + 1, m + 1) (r, m).This work was supported by a grant from the Research Council of Wright State University. 相似文献
9.
Gordon Simons 《Probability Theory and Related Fields》1978,42(2):167-173
Summary Let denote the class of infinite product probability measures =
1×
2× defined on an infinite product of replications of a given measurable space (X, A), and let denote the subset of for which (A) =0 or 1 for each permutation invariant event A. Previous works by Hewitt and Savage, Horn and Schach, Blum and Pathak, and Sendler (referenced in the paper) discuss very restrictive sufficient conditions under which a given member , of belongs to . In the present paper, the class is shown to possess several closure properties. E.g., if and
0
n
for some n 1, then
0×
1×
2×.... While the current results do not permit a complete characterization of they demonstrate conclusively that is a much larger subset of than previous results indicated. The interesting special case X={0,1} is discussed in detail.Research supported by the National Science Foundation under grant No. MCS75-07556 相似文献
10.
For a partition ={1230} of non-negative integers, we calculate the Euler characteristic of the local system on the moduli space of genus 3 hyperelliptic curves using a suitable stratification. For some of low degree, we make a guess for the motivic Euler characteristic of using counting curves over finite fields.Mathematics Subject Classification (1991): 14J15, 20B25 相似文献
11.
A. S. Zinov'ev 《Mathematical Notes》1972,12(5):743-746
We obtain sufficient conditions for the absolute convergence of Fourier series for functions of L
d
2
depending on the properties of the function being expanded and the rate of growth of the sums
of the system of functions {k(t)} orthonormalized in [a, b] with respect to d(t). We show that if at some point x [a, b] the function (t) has a discontinuity, at that point the Fourier series of any functionf(t) L
d
2
, converges absolutely.Translated from Matematicheskie Zametki, Vol. 12, No. 5, pp. 511–516, November, 1972. 相似文献
12.
Ju¨rg Hu¨sler 《Extremes》1999,2(1):59-70
Consider a triangular array of standard Gaussian random variables {n,i, i 0, n 1} such that {n,i, i 0} is a stationary normal sequence for each n 1. Let n,k = corr(n,i,n,i+k). If (1-n,k)log n k (0,) as n for some k, then the locations where the extreme values occur cluster and the limiting distribution of the maxima is still the Gumbel distribution as in the stationary or i.i.d. case, but shifted by a parameter measuring the clustering. Triangular arrays of Gaussian sequences are used to approximate a continuous Gaussian process X(t), t 0. The cluster behavior of the random sequence refers to the behavior of the extremes values of the continuous process. The relation is analyzed. It reveals a new definition of the constants H
used for the limiting distribution of maxima of continuous Gaussian processes and provides further understanding of the limit result for these extremes. 相似文献
13.
N. L. Gordeev 《Journal of Mathematical Sciences》2003,116(1):2961-2971
Let be a linear representation of a finite group over a field of characteristic 0. Further, let R
be the corresponding algebra of invariants, and let P
(t) be its Hilbert–Poincaré series. Then the series P
(t) represents a rational function (t)/(t). If R
is a complete intersection, then (t) is a product of cyclotomic polynomials. Here we prove the inverse statement for the case where is an almost regular (in particular, regular) representation of a cyclic group. This yields an answer to a question of R. Stanley in this very special case. Bibliography: 3 titles. 相似文献
14.
We give uniform estimates of entire functions of exponential type less than having sufficiently small logarithmic sums over real sequences {
n
} satisfying |
n
–n|L and
n+1–
n
for fixed positive constants L and . We thereby generalize results about logarithmic sums over the set of integers and so-called relatively h-dense sequences. 相似文献
15.
Let u v be positive superharmonic functions in a general potential-theoretic setting, where these functions have a Choquet-type integral representation by minimal such functions with Choquet charges (i.e. representing measures) and , respectively. We show that on the contact set {u – v = 0} of the -superharmonic function u – v, if this set is properly interpreted as the set of those minimal superharmonic functions s which satisfy lim sup T
s
v/u = 1 for the co-fine neighborhood filter T
s
associated with s. In the setting of classical potential theory for Laplace's equation this result improves on results obtained by Fuglede in 1992. 相似文献
16.
Wilhelm Forst 《Numerische Mathematik》1978,30(2):137-147
Summary Letx
0<x
1<...<x
n–1<x
0+2 be nodes having multiplicitiesv
0,...,v
n–1, 1v
k
r (0k<n). We approximate the evaluation functional
,x fixed, and the integral respectively by linear functionals of the form
and determine optimal weights
for the Favard classesW
r
C
2. In the even case
of optimal interpolation these weights are unique except forr=1,x(x
k
+x
k–1)/2 mod 2. Moreover we get periodic polynomial splinesw
k, j
(0k<n, 0j<v
k
) of orderr such that
are the optimal weights. Certain optimal quadrature formulas are shown to be of interpolatory type with respect to these splines. For the odd case
of optimal interpolation we merely have obtained a partial solution.
Bojanov hat in [4, 5] ähnliche Resultate wie wir erzielt. Um Wiederholungen zu vermeiden, werden Resultate, deren Beweise man bereits in [4, 5] findet, nur zitiert 相似文献
17.
Shiqi Song 《应用数学学报(英文版)》1993,9(2):115-124
LetX be the solution of the SDE:dX
t = (X
t)dB
t +b(X
t)dt, with andb C
b
(R) such that >0 for some constant , andB a real Brownian motion. Let be the law ofX onE=C([0, 1],R) andk E* – {0}, whereE* is the topological dual space ofE. Consider the classical form:
k
(u, v)=u / kv / kd, whereu andv are smooth functions onE. We prove that, if
k
is closable for anyk in a dense subset ofE* and if the smooth functions are contained in the domain of the generator of the closure of
k
, must be a constant function. 相似文献
18.
S. V. Solov'ev 《Journal of Mathematical Sciences》1982,20(4):2367-2369
We consider the (&, )-fragment of the intuitionistic propositional calculus. It is proved that under the standard transformation of a Gentzen derivation into a natural derivation(), the length of (())22·length(
). There is constructed a sequence of Gentzen derivations of length i, for which the length of ((
i))21/3·length(i), which shows that the upper bound obtained is not too weak.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 88, pp. 192–196, 1979. 相似文献
19.
LetG be a cyclicallyk-edge-connected cubic graph withk 3. Lete be an edge ofG. LetG be the cubic graph obtained fromG by deletinge and its end vertices. The edgee is said to bek-removable ifG is also cyclicallyk-edge-connected. Let us denote by S
k
(G) the graph induced by thek-removable edges and by N
k
(G) the graph induced by the non 3-removable edges ofG. In a previous paper [7], we have proved that N
3(G) is empty if and only ifG is cyclically 4-edge connected and that if N
3(G) is not empty then it is a forest containing at least three trees. Andersen, Fleischner and Jackson [1] and, independently, McCuaig [11] studied N
4(G). Here, we study the structure of N
k
(G) fork 5 and we give some constructions of graphs such thatN
k
(G) = E(G). We note that the main result of this paper (Theorem 5) has been announced independently by McCuaig [11].
Résumé SoitG un graphe cubique cyliquementk-arête-connexe, aveck 3. Soite une arête deG et soitG le graphe cubique obtenu à partir deG en supprimante et ses extrémités. L'arêtee est ditek-suppressible siG est aussi cycliquementk-arête-connexe. Désignons par S k (G) le graphe induit par les arêtesk-suppressibles et par N k (G) celui induit par les arêtes nonk-suppressibles. Dans un précédent article [7], nous avons montré que N 3(G) est vide si et seulement siG est cycliquement 4-arête-connexe et que si N 3(G) n'est pas vide alors c'est une forêt possédant au moins trois arbres. Andersen, Fleischner and Jackson [1] et, indépendemment, McCuaig [11] ont étudié N 4(G). Ici, nous étudions la structure de N k (G) pourk 5 et nous donnons des constructions de graphes pour lesquelsN k (G) = E(G). Nous signalons que le résultat principal de cet article (Théorème 5) a été annoncé indépendamment par McCuaig [11].相似文献
20.
Gábor Elek 《K-Theory》1998,13(1):1-22
We prove that, for any exact category M, any element of K1(M)can be described in terms of a pair of admissible monomorphisms A X, B Y and an isomorphism :A X/A Y B Y/B X. 相似文献