The Magnus Embedding for Right-Symmetric Algebras

We construct a basis for the universal multiplicative enveloping algebra U(A) of a right-symmetric algebra A. We prove an analog of the Magnus embedding for right-symmetric algebras; i.e., we prove that a right-symmetric algebra A/R ², where A is a free right-symmetric algebra, is embedded into the algebra of triangular matrices of the second order.     

The Magnus representation of the Torelli group

In this paper we consider the Magnus representation of the Torelli group. We prove that it is not faithful by showing a non-trivial element in the kernel of this representaion.

     

The Magnus embedding as a special case of a homological construction

Let E be a group extension with Abelian kernel. Then it can be assigned an extension E′ of modules over the group ring of the quotient group. As a consequence, an embedding of the initial extension in some splitting extension arises. We prove that the celebrated Magnus embedding is a special case of this general construction.     

Numerical Evaluation of the Evans Function by Magnus Integration

We use Magnus methods to compute the Evans function for spectral problems as arise when determining the linear stability of travelling wave solutions to reaction-diffusion and related partial differential equations. In a typical application scenario, we need to repeatedly sample the solution to a system of linear non-autonomous ordinary differential equations for different values of one or more parameters as we detect and locate the zeros of the Evans function in the right half of the complex plane. In this situation, a substantial portion of the computational effort—the numerical evaluation of the iterated integrals which appear in the Magnus series—can be performed independent of the parameters and hence needs to be done only once. More importantly, for any given tolerance Magnus integrators possess lower bounds on the step size which are uniform across large regions of parameter space and which can be estimated a priori. We demonstrate, analytically as well as through numerical experiment, that these features render Magnus integrators extremely robust and, depending on the regime of interest, efficient in comparison with standard ODE solvers. AMS subject classification (2000) 65F20     

On the probability of Magnus Carlsen reaching 2900

How likely is it that Magnus Carlsen will achieve his goal of a 2900 Elo rating? At what level of play does Magnus have a reasonable chance of reaching the 2900 goal? These two questions are of great current interest to Magnus and the chess community. The probabilistic properties of Elo's rating system are well known, and together with a Brownian motion model of rating evolution, we use simulation-based methods to address these questions. Our model assesses that Magnus has a 4.5% chance of reaching 2900 if he continues his 2020–2022 level of play. However, this increases dramatically to $80$% chance if he can repeat his hot streak performance of 2019 which is not an easy undertaking. The probabilities are intimately related to Elo's choice $K$-factor used for grandmaster chess play. Finally, we conclude with a discussion of the policy issues involved with the choice of $K$-factor.     

直觉模糊群的子直觉模糊群和正规子直觉模糊群

设G为直觉模糊二元运算下的直觉模糊群,给出了G子直觉模糊群和正规子直觉模糊群的定义,讨论并证明了子直觉模糊群和正规子直觉模糊群的一些性质。     

Group solution of a time dependent chemical convective process

The time dependent progress of a chemical reaction over a flat vertical plate is here considered. The problem is solved using the two parameter group method which reduces the number of independent by one and leads to a set of nonlinear ordinary differential equation. The behavior of the process is numerically investigated for the chemical reaction order and different Schmidt numbers. As the problem shows a singularity at n = 1, the nonlinear system of ordinary differential equation resulting from the transformation of the problem are analytically solved through the perturbation method. The velocity and concentration of chemicals based on the analytical and numerical solutions are presented, compared and discussed.     

格群的T—Fuzzy子格群

引入格群L关于t-norm T的Fuzzy子格群、Fuzzy正则子格群（简称T-Fuzzy子格群、T-Fuzzy正规子格群）等概念,研究它们的性质,给出T-Fuzzy子格群的刻画。     

特征单群的模糊子群构造

通过研究特征单群的合成群列和子群链的构造特点,得出了能够反映特征单群的模糊子群构造特征的极大Fuzzy子群的阶和等价类数以及Fuzzy子群的等价类数的公式.     

Irreducible Subgroups of GL 1(D) Satisfying Group Identities

ABSTRACT

Let D be a finite dimensional F -central division algebra and G an irreducible subgroup of D*: = GL ₁(D). Here we investigate the structure of D under various group identities on G. In particular, it is shown that when [D:F] = p ², p a prime, then D is cyclic if and only if D* contains a nonabelian subgroup satisfying a group identity.     

The Isomorphism Problem for Integral Group Rings of a Complete Monomial Group

Let G be a complete monomial group with abelian base, namely, G = AwrSym _m , the wreath product of a finite abelian group A with the symmetric group on m letters. Then the group G is determined by its integral group ring.     

The Cohomologies of the Sylow 2-Subgroups of a Symplectic Group of Degree Six and of the Third Conway Group

The third Conway group Co ₃ is one of the 26 sporadic finite simple groups. The cohomology of its Sylow 2-subgroup S is computed, an important step in calculating the mod 2 cohomology of Co ₃. The spectral sequence for the central extension of S is described; it collapses at the sixth page. Generators are described in terms of the Evens norm or transfers from subgroups. The central quotient S′ = S/2 is the Sylow 2-subgroup of the symplectic group Sp ₆(𝔽₂) of six-by-six matrices over the field of two elements. The cohomology of S′ is computed and is detected by restriction to elementary abelian 2-subgroups.     

The Generalised Pro-Fitting Subgroup of a Profinite Group

The generalised Fitting subgroup of a finite group is the group generated by all subnormal subgroups that are either nilpotent or quasisimple. The importance of this subgroup in finite group theory stems from the fact that it always contains its own centraliser, so that any finite group is an abelian extension of a group of automorphisms of its generalised Fitting subgroup. We define a class of profinite groups which generalises this phenomenon, and explore some consequences for the structure of profinite groups.     

The Primitive Idempotents of a Cyclic Group Algebra

Explicit expressions are obtained for the 2n + 1 primitive idempotents in FG, the semisimple group algebra of the cyclic group G of order pⁿ (p an odd prime, n ≥ 1) over the finite field F of prime power order q, when q has order φ(pⁿ)/2 modulo pⁿ.AMS Mathematical Subject Classification (2000): 20C05, 94B05, 12E20, 16S34.     

由两个M bius变换生成的群产生的极限集的分形结构

讨论了一种以两个 M bius变换为生成元的群作用在单位圆周 S1上的一段弧上所形成的极限集的分形结构     

Unitary Units Satisfying a Group Identity

Let K be a nonabsolute field of characteristic p ≠ 2, G a locally finite group and KG its group algebra. Let ?: KG → KG denote the K-linear extension of an involution ? defined on G. In this article, we prove that if the subgroup 𝒰_?(KG), i.e., the ?-unitary units of KG, satisfies a group identity, then KG satisfies a polynomial identity. Moreover, in case the prime radical of KG is nilpotent, we characterize the groups G for which 𝒰_?(KG) satisfies a group identity.     

The Meta-Grothendieck Group of a Ring

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