共查询到20条相似文献,搜索用时 406 毫秒
1.
We derive a formula for expressing free cumulants whose entries are products of random variables in terms of the lattice structure of non-crossing partitions. We show the usefulness of that result by giving direct and conceptually simple proofs for a lot of results about R-diagonal elements. Our investigations do not assume the trace property for the considered linear functionals. 相似文献
2.
商家提供产品免费试用,要求试用者对产品质量进行在线评论,消费者基于在线评论进行购买决策。免费试用者数量越多,在线评论数量越多,消费者对在线评论越信任。考虑在线评论和产品生产成本,研究商家的产品免费试用策略及其对利润的影响。研究发现,虽然商家承受免费试用的产品生产成本损失,但是免费试用产生的在线评论可以使商家更好地按照产品质量制定价格,因此当产品生产成本较低时,提供免费试用可以提高商家利润。产品生产成本提高,商家的最优免费试用数量减少。产品质量不确定性越大或失配距离单位成本越低,免费试用给商家带来的收益越高。 相似文献
3.
Federico Berlai 《代数通讯》2013,41(7):2959-2980
Let 𝒞 be a class of groups. We give sufficient conditions ensuring that a free product of residually 𝒞 groups is again residually 𝒞, and analogous conditions are given for LE-𝒞 groups. As a corollary, we obtain that the class of residually amenable groups and the one of locally embeddable into amenable (LEA) groups are closed under taking free products.Moreover, we consider the pro-𝒞 topology and we characterize special HNN extensions and amalgamated free products that are residually 𝒞, where 𝒞 is a suitable class of groups. In this way, we describe special HNN extensions and amalgamated free products that are residually amenable. 相似文献
4.
环的左自由正规化扩张和拟Excellent扩张 总被引:1,自引:0,他引:1
本文引进了环的左自由正规化扩张和拟Excelent扩张,并将环的Excelent扩张的一些性质推广到了左自由正规化扩张和拟Excelent扩张,主要讨论了几乎Noether性,正则性,凝聚性和半遗传性. 相似文献
5.
Roger C. Alperin 《Linear and Multilinear Algebra》1995,38(3):215-223
In this note we give some new examples of matrix groups which are free products. We use this in our study of the Burau representation in dimension four. 相似文献
6.
Yu. L. Ershov 《Algebra and Logic》1996,35(2):86-95
We bring in the notion of a Δ*-group and prove that it is in essence an axiomatic closure (in the language of CDM-presentations) of the class of Δ*-groups, which are naturally determined from free products of strict etale spaces. The present account is aimed at advancing
some results on free Δ*-groups obtained within model theory of RC*-fields.
Translated fromAlgebra i Logika, Vol. 35, No. 2, pp. 154–172, March–April, 1996. 相似文献
7.
S. M. Gersten 《代数通讯》2013,41(1):39-64
The object of this article is to establish the following result (Corollary 3.9 below): If R is a regular right noetherian ring and R{X} is the free associative algebra on the set X, then Kn(R) = Kn(R{X}), where Kn refers to the Quillen K-theory. The result can be stated in the equivalent form that Hn(G1(R),Z) = Hn(G1(R{X}),Z). From this result it follows that if F is a free ring without unit, then Kn(F) = 0, whence free rings are acyclic models for Quillen K-theory (3.11 below). This result in turn enables us to complete Anderson's work [1] in identifying the Quillen K-theory [11] and the K-theory proposed by Gersten [7] and Swan [18] for all rings. We also establish that the natural transformation Kn(R) → Kn k-v(R) between the Quillen theory and the K-theory of Karoubi and Villamayor is an isomorphism if R is a supercoherent (Definition 1.2) and regular (Definition 1.3) ring. From this result we can gain some information about the K-theory of group rings of free products of groups (Theorem 5.1). 相似文献
8.
Brown Nathanial P.; Dykema Kenneth J.; Jung Kenley 《Proceedings London Mathematical Society》2008,97(2):339-367
We calculate the microstates free entropy dimension of naturalgenerators in an amalgamated free product of certain von Neumannalgebras, with amalgamation over a hyperfinite subalgebra. Inparticular, some exotic Popa algebra generatorsof free group factors are shown to have the expected free entropydimension. We also show that microstates and non-microstatesfree entropy dimension agree for generating sets of many groups.In the appendix, the first L2-Betti number for certain amalgamatedfree products of groups is calculated. 相似文献
9.
目前,提供限时免费试用已经成为软件厂商降低消费者对产品质量不确定性及促进新产品扩散的常见做法。现有研究多局限于垄断情况,对现实中常出现的寡头竞争情况鲜有探讨。在考虑消费者学习异质性的基础上,基于Hotelling模型研究了双寡头企业免费试用策略博弈均衡及其影响因素。结果表明:(1)如果两家企业的期望用户体验都比较好,都应该提供免费试用;如果期望用户体验都比较差,都不提供。(2)否则,均衡结果进一步取决于消费者对他们之间水平差异的敏感性。如果很不敏感,则两家企业必须采取相反的免费试用提供策略,并且只有当它们的期望用户体验差距很大时,优势企业一定提供而劣势企业不提供;否则,保持相反即可。如果非常敏感,则两家企业只需在免费试用提供策略上保持一致即可。(3)消费者完全学习软件所需时间越长,两家企业“都不提供”和“只需一致”的可能性增大,而“都提供”和“必定相反”的可能性降低。这是对免费试用策略竞争问题进行的首次探索,所得结果对相关理论研究具有补充和促进作用,也能为相关实践提供科学的决策依据。 相似文献
10.
Vladimir V. Yedynak 《代数通讯》2013,41(9):3448-3455
We introduce the notion of multielement order separability and study this property for free groups and free products. 相似文献
11.
Nathaniel Pappas 《代数通讯》2013,41(10):4515-4527
We calculate the rank gradient and p-gradient of free products with amalgamation over an amenable subgroup and HNN extensions with an amenable associated subgroup. The notion of cost is used to compute the rank gradient of amalgamated free products and HNN extensions. For the p-gradient the Kurosh subgroup theorems for amalgamated free products and HNN extensions will be used. 相似文献
12.
John Williams 《Complex Analysis and Operator Theory》2012,6(1):23-31
We prove results about uniform convergence of densities in the free central limit theorem without assumptions of boundedness
on the support. 相似文献
13.
Maximization problems are solved for Voiculescu's free entropy of probability measures supported in R, R+, and [-1, 1], respectively, under constraint of the pth moment for any p > 0 and implications of these results for multivariate free entropy are discussed in the setting of noncommutative random variables. Similar extremum problems are treated for probability measures on C and Tunder certain constraints. The elliptic law and a distribution found earlier in quantum physics are encountered. These results are in the setting of potential theory and can be viewed independently from Voiculescu's work. The machinery of weighted potentials is exploited. 相似文献
14.
15.
Azarian M K将Tang C Y得到的关于两个群的带循环融合自由积的Frattini子群的一个定理推广到任意多个子群的带循环融合自由积的情况.通过考虑任意多个子群的带循环融合自由积的πnFrattini子群和πcFrattini子群,得到了类似的结果. 相似文献
16.
We prove that, with rare exceptions, groups that are free products with amalgamation or HNN-extensions are of uniformly exponential
growth.
Translated fromMatematicheskie Zametki, Vol. 67, No. 6, pp. 811–815, June, 2000. 相似文献
17.
18.
O. V. Sipacheva 《Journal of Mathematical Sciences》2005,131(4):5765-5838
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20.
A graph G is free (a, b)-choosable if for any vertex v with b colors assigned and for any list of colors of size a associated with each vertex \(u\ne v\), the coloring can be completed by choosing for u a subset of b colors such that adjacent vertices are colored with disjoint color sets. In this note, a necessary and sufficient condition for a cycle to be free (a, b)-choosable is given. As a corollary, we obtain almost optimal results about the free (a, b)-choosability of outerplanar graphs. 相似文献