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1.
P. Simon 《Algebra Universalis》1996,36(4):450-456
We construct in ZFC a compactificationb of integers such that the Boolean algebra Clopen(b) is tree-like and every one-to-one continuous mapping as well as every continuous onto mapping fromb tob is a homeomorphism, and every homeomorphism fromb onto itself is identity at all except finitely many points from .Presented by J. Mycielski.The research was supported by the grant GAUK 350.The author owes sincere thanks to the referee, whose comments bridged many gaps in the first version of the present paper. 相似文献
2.
Luise Unger 《manuscripta mathematica》1986,57(1):1-31
Let
be the path algebra for some representation-infinite quiver
over some field k. There exists a bound
such that mI is faithful for all indecomposable injective
-modules I and all
, and such that there exists an indecomposable injective
-module J satisfying that
J is not faithful, denotes the Auslander-Reiten-translation. Let m() be the maximum of the
taken over all possible orientations of the underlying graph . In this article we determine the bounds m() for representation-infinite quivers
for which is a tree. 相似文献
3.
Summary This paper solves the second of two variational problems arising in the study of an infinite system of particles that branch and migrate in a random medium. This variational problem involves a non-linear functional on a subset of the stationary probability measures on [×+], describing the interplay between particles and medium. It is shown that the variational problem can be solved in terms of the Lyapunov exponent of a product of random × matrices. This Lyapunov exponent is calculated via a random continued fraction. By analyzing the latter we are able to compute the maximum and the maximizer in the variational problem. It is found that these quantities exhibit interesting non-analyticities and changes of sign as a function of model parameters, which correspond to phase transitions in the infinite particle system. By combining with results from Part I we obtain a complete picture of the phase diagram. 相似文献
4.
Franz Peherstorfer 《Numerische Mathematik》1987,52(3):317-327
Summary It is well known that the Chebyshev weight function (1–x
2)–1/2 is the only weight function (up to a linear transformation) for which then point Gauss quadrature formula has equal weights for alln. In this paper we describe all weight functions for which thenm point Gauss quadrature formula has equal weights for alln, wherem is fixed. 相似文献
5.
Toivo Leiger 《manuscripta mathematica》1984,45(3):293-307
Let A and B be normal matrices. In :={x=(xk) ¦ xk} we define the order relation A by xA0:<=>
k=0
n
ankxk0 (n ). Let T be a row-finite matrix. A is called T-section-positive, if ktmkxke(k) A0 (m ) for xA0 (see [5]). We study the relation between T-sectional positivity and T-sectional boundedness. An (A,B)-summability factor sequence =(k) is called positive, if (kxk)B0 for each xcA with xA0. For B-section-positive matrices A we give a functional analytic characterization of positive (A,B)-summability factor sequences.
Die Arbeit entstand während eines vom DAAD unterstützten Forschungsaufenthalts an der Fernuniversität-Gesamthochschule Hagen 相似文献
Die Arbeit entstand während eines vom DAAD unterstützten Forschungsaufenthalts an der Fernuniversität-Gesamthochschule Hagen 相似文献
6.
Let be the set of nonnegative integers and the ring of integers. Let
be the ring of N × N matrices over generated by the following two matrices: one obtained from the identity matrix by shifting the ones one position to the right and the other one position down. This ring plays an important role in the study of directly finite rings. Calculation of invertible and idempotent elements of
yields that the subrings generated by them coincide. This subring is the sum of the ideal
consisting of all matrices in
with only a finite number of nonzero entries and the subring of
generated by the identity matrix. Regular elements are also described. We characterize all ideals of
, show that all ideals are finitely generated and that not all ideals of
are principal. Some general ring theoretic properties of
are also established. 相似文献
7.
Hansmartin Zeuner 《Journal of Theoretical Probability》1994,7(2):225-245
Let (X
n:n) be i.i.d. with finite variance and values in a hypergroupK:=+ or and
j=1
n
X
j
be the randomized sum of these random variables. It is shown that the processes
converge in distribution to a Gaussian process in the caseK=+, that the processes
converge towards a Bessel process on + in the case of polynomial growth of the hypergroupK=+ or , and that in the case of exponential growth
converges towards a Brownian motion asn. 相似文献
8.
Summary LetX
n, n
d
be a field of independent random variables taking values in a semi-normed measurable vector spaceF. For a broad class of fields n, d of positive numbers, the almost sure behaviour of knXk/n, n d is studied. The main result allows us to deduce some new and well-known theorems for fields of independentF random variables from related results for fields of independent real random variables.Supported in part by the Youth Science Foundation of China, No. 19001018Supported by the National Natural Science Foundation of China 相似文献
9.
10.
The local tree-width of
a graph G=(V,E) is the function
ltwG : that associates
with every r the maximal
tree-width of an r-neighborhood in
G. Our main grapht heoretic
result is a decomposition theorem for graphs with excluded
minors, which says that such graphs can be decomposed into trees
of graphs of almost bounded local tree-width.As an application of this theorem, we show that a number
of combinatorial optimization problems, suchas
Minimum Vertex Cover,
Minimum Dominating Set,
and Maximum Independent
Set have a polynomial time approximation scheme when
restricted to a class of graphs with an excluded minor. 相似文献
11.
Ruy Exel 《Bulletin of the Brazilian Mathematical Society》1994,25(2):173-179
We describe both the Bunce-DeddensC
*-algebras and their Toeplitz versions, as crossed products of commutativeC
*-algebras by partial automorphisms. In the latter case, the commutative algebra has, as its spectrum, the union of the Cantor set and a copy of the set of natural numbers , fitted together in such a way that is an open dense subset. The partial automorphism is induced by a map that acts like the odometer map on the Cantor set while being the translation by one on . From this we deduce, by taking quotients, that the Bunce-DeddensC
*-algebras are isomorphic to the (classical) crossed product of the algebra of continuous functions on the Cantor set by the odometer map. 相似文献
12.
Edgar R. Lorch 《Integral Equations and Operator Theory》1981,4(3):422-434
The objects studied are the subalgebras of
which contain co. These are isometrically isomorphic to the algebras C(
) where
is a compactification of a discrete denumerable set N . It is shown: 1) If
is metric then there is a projection of norm 1, P: C(
) C(
) with kernel co defined by PF = f o where is a retraction of
onto
=
– N . 2) If
is metric, then the group of homeomorphisms of
is isomorphic to a complete group of permutations of the natural numbers . 3) The group of homeomorphisms of a compact metric space is the homomorphic image of a complete group of permutations of ("complete" means "no outer automorphisms, trivial center"). 相似文献
13.
V. G. Chernov 《Ukrainian Mathematical Journal》1990,42(3):331-336
We study the algebra of functions on the set of natural numbers with respect to the generalized convolution, generated by the generalized translation operator Tnf(k)=f(max (n, k)), n, k. With the help of the generalized Fourier transform, connected with this convolution, we establish numerous identities and recurrence relations, connecting, in particular, sums of powers of natural numbers.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 3, pp. 372–377, March, 1990. 相似文献
14.
Alexander Kreuzer 《Geometriae Dedicata》1996,61(3):279-283
Let (P,
) and (P,
) be linear spaces satisfying the exchange axiom with dim P=dim P . Then a bijection :PP which maps collinear points onto collinear points is an isomorphism. Also a surjection :PP which maps any three non-collinear points to non-collinear points is an isomorphism. This assertion is not true if dim P is not finite. 相似文献
15.
In topological linear spaces convex hulls of bounded sets are, in general, not bounded. The question arises whether there is at least for every bounded set B a sequence {|} of strictly positive numbers such that the set {
l
n
v
B|n} is bounded. When this obtains, bounded sets share several of the properties known in locally convex spaces. The main result of this note is an example of a countable inductive limit of complete metrizable topological linear spaces which is neither regular nor sequentially complete and also fails to have the above bounded summability property. 相似文献
16.
Siegfried Nobel 《Journal of Theoretical Probability》1991,4(2):261-284
LetX
1,X
2,... be i.i.d. random variables with values in a simply connected nilpotent Lie groupG. Assume the laws of
to be weakly convergent to a probability measure onG,
n
Aut(G), and (k
n)n strictly increasing in. In this paper we want to characterize the possible limit laws. We obtain that every limit law is continuously embeddable and we prove a kind of functional limit theorem. Further, we study the connections between two different concepts of stability (resp. semistability) and limit laws. Finally, we describe the various domains of attraction of measures (resp. of convolution semigroups). 相似文献
17.
Let M be a real submanifold of an almost complex manifold
and let
be the maximal holomorphic subspace, for each x M. We prove that c:M,c(x)=dim
H
x
is upper-semicontinuous. 相似文献
18.
Tomasz Rolski 《Probability Theory and Related Fields》1990,84(1):27-37
Summary We discuss in this paper a non-homogeneous Poisson process A driven by an almost periodic intensity function. We give the stationary version A
* and the Palm version A
0 corresponding to A
*. Let (T
i
,i) be the inter-point distance sequence in A and (T
i
0
,i) in A
0. We prove that forj, the sequence (T
i+j,i) converges in distribution to (T
i
0
,i). If the intensity function is periodic then the convergence is in variation. 相似文献
19.
Franz Peherstorfer 《Numerische Mathematik》1990,58(1):273-286
Summary It is well known that the Tchebycheff weight function (1-x
2)–1/2 is the only weight function (up to a linear transformation) for which then point Gauss quadrature formula has equal weights for alln. In this paper we describe explicitly all weight functions which have the property that then
k-point Gauss quadrature formula has equal weights for allk, where (n
k),n
1<n
2<..., is an arbitrary subsequence of . Furthermore results on the possibility of Tchebycheff quadrature on several intervals are given. 相似文献
20.
V. A. Belonogov 《Algebra and Logic》2005,44(1):13-24
In the representation theory of symmetric groups, for each partition of a natural number n, the partition h() of n is defined so as to obtain a certain set of zeros in the table of characters for Sn. Namely, h() is the greatest (under the lexicographic ordering ) partition among P(n) such that (g) 0. Here, is an irreducible character of Sn, indexed by a partition , and g is a conjugacy class of elements in Sn, indexed by a partition . We point out an extra set of zeros in the table that we are dealing with. For every non self-associated partition P(n), the partition f() of n is defined so that f() is greatest among the partitions of n which are opposite in sign to h() and are such that (g) 0 (Thm. 1). Also, for any self-associated partition of n > 1, we construct a partition
() P(n) such that
() is greatest among the partitions of n which are distinct from h() and are such that (g) 0 (Thm. 2).Supported by RFBR grant No. 04-01-00463 and by RFBR-BRFBR grant No. 04-01-81001.Translated from Algebra i Logika, Vol. 44, No. 1, pp. 24–43, January–February, 2005. 相似文献