共查询到20条相似文献,搜索用时 46 毫秒
1.
设A为有单位且包含一非平凡幂等元的环,M为A双模.称δ:A→M为Lie可导映射(无可加或连续假设),若δ([A,B])=[δ(A),B]+[A,δ(B)],(?)A,B∈A.在一定条件下该文证明了Lie可导映射δ具有形式δ(A)=τ(A)+f(A),其中r:A→M是可加导子,f是从A到M的中心且满足f([A,B])=0,(?)A,B∈A的映射.由此刻画了因子von Neuamnn代数和套代数上的Lie可导映射. 相似文献
2.
Takashi Yoshino 《Israel Journal of Mathematics》1991,75(2-3):273-275
In 1982, S. Friedland proved that a bounded linear operator A on a Hilbert space is normal if and only if (αI + A + A*)2 ≧ AA* − A*A ≧ −(αI + A + A*)2 for all real α. And he conjectured the inequality (αI + A + A*)2 ≧ AA* − A*A for all real α will imply that A*A − AA* ≧ 0, i.e., A is hyponormal. But his conjecture is incorrect. In this
note I’ll give a counter-example for his conjecture. 相似文献
3.
4.
Let A = {а 1 < a 2 < ...} be a set of positive integers and A(x) its counting function. Let us denote the number of partitions of n with parts in A by p( A , n). Improving on two preceding papers jointly written with I.Z. Ruzsa and A. Sárközy (J. Number Theory, 1998) and with A. Sárközy (Millennial Conference on Number Theory, May 2000, Urbana, Illinois, U.S.A.), it is shown that there exists a set A satisfying A(x) > c xlog log x/ (log x) 1/3 , c<0, such that, for n large enough, p( A ; n) isalways even. 相似文献
5.
设A是一个的因子von Neumann代数.我们证明了每一个非线性混合ξ-Jordan(ξ≠0,-1)三重可导映射φ:A → A都是可加的*-导子,且对任意的A ∈ A,有φ(ξA)=ξφ(A). 相似文献
6.
7.
A strong negative answer is given to the old question of whether every dual group is reflexive. Using ◊ω1 a groupA is constructed so thatA, A*, A**, andA*** are weakly ω1-separable groups of cardinalityω
1 andA* is not isomorphic toA***.
Research partially supported by NSF Grant No. DMS-8400451.
Research partially supported by NSERC Grant No. A8948. 相似文献
8.
Michael Frank 《Annals of Global Analysis and Geometry》1985,3(2):155-172
Let A be a C*-algebra, K be a compact space, A(K) be the C*-algebra of all continuous maps from K into A, 12(A) be the standard countably generated Hilbert A-module. We investigate a set of maps from K into EndA(12(A)), which is isomorphic to EndA(K)(12(A(K))). We describe the subsets which are isomorphic to EndfA(K)
*(12(A(K))). GLA(K)(12(A(K))) and GLfA(K)
*(12(A(K))), respectively. As an application we deduce a criterion for the self-duality of 12(A) in the commutative case. 相似文献
9.
Suppose A is a unital C*-algebra and r 1.In this paper,we define a unital C*-algebra C_(cb)*(A,r) and a completely bounded unital homomorphism α_r:A → C_(cb)*(A,r)with the property that C_(cb)*(A,r)=C*(α_r(A))and,for every unital C*-algebra B and every unital completely bounded homomorphism φ:A→ B,there is a(unique)unital *-homomorphism π:C_(cb)*(A,r)→B such thatφ=πoα_r.We prove that,if A is generated by a normal set {t_λ:λ∈Λ},then C_(cb)*(A,r)is generated by the set {α_r(t_λ):λ∈Λ}.By proving an equation of the norms of elements in a dense subset of C_(cb)*(A,r)we obtain that,if Β is a unital C*-algebra that can be embedded into A,then C_(cb)*(B,r)can be naturally embedded into C(cb)*(A,r).We give characterizations of C_(cb)*(A,r)for some special situations and we conclude that C_(cb)*(A,r)will be "nice" when dim(A)≤ 2 and "quite complicated" when dim(A)≥ 3.We give a characterization of the relation between K-groups of A and K-groups of C_(cb)*(A,r).We also define and study some analogous of C_(cb)*(A,r). 相似文献
10.
Kensaku Gomi 《Logica Universalis》2009,3(2):243-291
A logical space is a pair (A, B){(A, {\mathcal{B}})} of a non-empty set A and a subset B{{\mathcal{B}}} of P A{{\mathcal{P}} A} . Since P A{{\mathcal{P}} A} is identified with {0, 1}A and {0, 1} is a typical lattice, a pair (A, F){(A, {\mathcal{F}})} of a non-empty set A and a subset F{{\mathcal{F}}} of
\mathbbBA{{\mathbb{B}}^A} for a certain lattice
\mathbbB{{\mathbb{B}}} is also called a
\mathbbB{{\mathbb{B}}} -valued functional logical space. A deduction system on A is a pair (R, D) of a subset D of A and a relation R between A*
and A. In terms of these simplest concepts, a general framework for studying the logical completeness is constructed. 相似文献
11.
Marilyn Breen 《Israel Journal of Mathematics》1972,11(4):347-348
It is possible to prove the following “Helly-type” thorem fork-almost-neighborly sets.
Theorem.A ⊆R
d is k-almost-neighborly if and only if every 2d+1 member subset of A is k-almost-neighborly. Moreover, if A ⊆bdry conv A, then A is k-almost-neighborly if and only if every 2d member subset of A is k-almost-neighborly. Each bound is best possible. 相似文献
12.
Let A, B be rings and P a radical property. Call B an A-Algebra if B is an A-bimodule such that (ba)b1 = b(ab1), (bb1)a = b(b1a), a(bb1) = (ab)b1 for any a ∈ A and any b,b1 ∈ B. A ring R, written as R = A ? B, is called a quasi-direct sum of (A, B) if A is a subring of R, B is an ideal of R and R is a direct sum of A and B as additive groups. The following results are obtained: 1. A quasi-direct sum of (A, B) is uniquely determined by an A-Algebra B (up to isomorphism); 2. The P-radical of the Algebra B is the same as the P-radical of the ring B; 3. P(A ? B) = P(A) +(B) if and only if P(A)B + BP(A) ? P(B); 4. If B has an identity e then P(A ? B) = P(A)(1?e) + P(B); 5. If P(Z) = 0 for the integer ring Z, then P(Mn(R)) = Mn(P(R)) holds for all rings R if and only if the above equality holds for all unitary rings R. In addition, some relationships of radicals between rings (or algebras over a field, semigroup algebras, etc.) and their corresponding identity extensions are discussed. 相似文献
13.
J.A. Loustau 《代数通讯》2013,41(12):2523-2535
Given a nonassociative algebra A and an Arens pair A1, A2, for A, we identify a subalgcbra ? of A2 with i (A) ? A ? A2 and show that ? better reflects the algebraic structure ot A, in parti-cular. any multilinear identity satisfied by ? is also satisfied by ? Hence, ? is commutative or Lie when A is and Jordan when A is a Jordan algebra of characteristic not 2 or 3. Also, we list examples (1) where ? = EndD(V) for A a primitive, associative algebra with commuting ring D and irreducible faithful module V,(2) where ? is the norm closure of A in the arens algebra of all bounded functionals of the bounded functionals for a normed algebra A and (3) where ? is the Arens algebra of all bounded functionals of the bounded functionals with A again normed. Note that dif-ferent Arens closures can arise form the same choice of A, A1, , A2 since ? is determined by A, A1, A2 and subspaces A3 ? A2 *, A4,?A3 *. 相似文献
14.
令H是维数大于2的复Hilbert空间,A是H上自伴标准算子代数.对于给定的正整数k≥1,H上算子A与B的k-斜交换子递推地定义为*[A,B]k=*[A,*[A,B]k-1],其中*[A,B]0=B,*[A,B]1=AB-BA*.设k≥4,φ是A上的值域包含所有一秩投影的映射.本文证明了φ满足*[φ(A),φ(B)]k=*[A,B]k对任意A,B∈A都成立的充分必要条件是φ(A)=A对任意A∈A都成立,或φ(A)=-A对任意A∈A都成立.当k是偶数时后一情形不出现. 相似文献
15.
Xiangxing Tao & Yunpin Wu 《分析论及其应用》2012,28(3):224-231
In this paper,the authors prove that the multilinear fractional integral operator T A 1,A 2 ,α and the relevant maximal operator M A 1,A 2 ,α with rough kernel are both bounded from L p (1 p ∞) to L q and from L p to L n/(n α),∞ with power weight,respectively,where T A 1,A 2 ,α (f)(x)=R n R m 1 (A 1 ;x,y)R m 2 (A 2 ;x,y) | x y | n α +m 1 +m 2 2 (x y) f (y)dy and M A 1,A 2 ,α (f)(x)=sup r0 1 r n α +m 1 +m 2 2 | x y | r 2 ∏ i=1 R m i (A i ;x,y)(x y) f (y) | dy,and 0 α n, ∈ L s (S n 1) (s ≥ 1) is a homogeneous function of degree zero in R n,A i is a function defined on R n and R m i (A i ;x,y) denotes the m i t h remainder of Taylor series of A i at x about y.More precisely,R m i (A i ;x,y)=A i (x) ∑ | γ | m i 1 γ ! D γ A i (y)(x y) r,where D γ (A i) ∈ BMO(R n) for | γ |=m i 1(m i 1),i=1,2. 相似文献
16.
Grazia Tamone 《Annali di Matematica Pura ed Applicata》1977,112(1):285-304
Summary We give some characterizations of noetherian domains A such that ? every irreducible element generates a primary ideal ?.
This condition, called (α)-property, is equivalent to the unique factorization if A is normal or a polynomial ring A=B[T].
If A is a1-dimensional k-algebra, the property (α) is equivalent to the vanishing of some Picard groups asPicA,Pic (A[T, T−1]),Pic (A|T|s), where S={Tn, n εZ}. We give not trivial examples of (α)-rings which aren’t factorial.
Entrata in Redazione il 6 febbraio 1976.
Lavoro eseguito nell’ambito della sezione n. 3 del G.N.S.A.G.A. del C.N.R. 相似文献
Entrata in Redazione il 6 febbraio 1976.
Lavoro eseguito nell’ambito della sezione n. 3 del G.N.S.A.G.A. del C.N.R. 相似文献
17.
Let (A,M) be a local, one-dimensional, Cohen-Macaulay ring of multiplicity e=e(A)>1 and Hilbert function H(A). Let I=AnnA (B/A) be the conductor of A in its blowing up B. Northcott and Matlis have proved that if the embedding dimension emdim A
of A is 2 then I=Me−1 [3; Corollary 13.8]. If emdim A>2 little is know about I. In [6] and [7] I is computed when the associated graded ring G(A) is reduced (in this case B in the integral closure of A). In this paper
we compute I when A is Gorenstein. There are in general upper and lower bounds for I in terms of a power of M and we start
discussing when these bounds are attained. In particular we show that in the extremal situation I=Me−1 one has emdimA=2 (thus inverting the result of Northcott and Matlis). Then we consider the case of Gorenstein rings. We prove
that if G(A) in Gorenstein then I=Mϑ where ϑ=Min{n‖H(n)=e}. If more generally A is Gorenstein then I⊂M2 or emdim A=e(A)=2. When A is the local ring of a curve at a singular point p we get, as a consequence of this last result
a proof of the following conjecture of Catanese which has interesting geometric applications [1]: if the conductor J of A in its normalization is not contained in M2 then p is a node. 相似文献
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19.
为探究企业战略风险度和偏离度对并购行为的影响,本文以沪深A股2010~2017为样本数据,基于Logit和Possion模型对企业战略与并购行为的影响机制进行实证检验。结果显示:企业战略风险度与并购行为显著正相关,表明企业战略越是风险偏好型的企业,其并购倾向越高,并购次数越多;企业战略偏离度与并购行为显著负相关,表明企业战略越是偏离同行常规战略的企业,其并购倾向越低,并购次数越少。进一步研究表明,完善的内部控制、较高的薪酬激励和聘请稳健的高管能够有效约束由企业战略引起的过度并购和并购不足行为,促进并购行为合理化。本文基于企业战略视角研究并购倾向和并购次数,有助于理解并购行为形成的内在机制,同时,对上市公司并购行为的治理和风险管控亦提供了新的线索和证据。 相似文献
20.
J. Bourgain 《Israel Journal of Mathematics》1984,48(4):289-304
It is shown that form≠n the polydisc algebrasA(D
m) andA(D
n) are not isomorphic as Banach spaces. More precisely, there is no linear embedding of the dual spaceA(D
n)* intoA(D
m)* form<n. The invariant is infinite dimensional and is based on certain, multi-indexed martingales related to those considered by
Davis et al. [10]. In the one-dimensional case, i.e. for the spaceA(D)*, a finite inequality is proved, implying thatA(D
2)* is not finitely representable inA(D)*. Extensions to algebras on products of strictly pseudoconvex domains are outlined. They imply in particular the non-isomorphism
of certain algebras in the same number of variables, for instance A (D4) ≠ A (B2xB2). 相似文献