Equational type characterization for σ-complete MV-algebras

In the framework of algebras with infinitary operations, an equational base for the category of σ-complete MV-algebras is given. In this way, we study some particular objects as simple algebras, directly irreducible algebras, injectives, etc. A completeness theorem with respect to the standard MV-algebra, considered as σ-complete MV-algebra, is obtained. Finally, we apply this result to the study of σ-complete Boolean algebras and σ-complete product MV-algebras.     

ℰ-complete andD-generic filters of partially ordered sets

In this paper we prove theorems which ensure the existence of -complete andD-generic filters of partially ordered sets.     

On σ-Embedded and σ-n-Embedded Subgroups of Finite Groups

Siberian Mathematical Journal - Let G be a finite group, and let σ = {σi | i ∈ I} be a partition of the set of all primes ℙ and σ(G) = {σi | σi ∩...     

Characterization of residual σ-algebras

The behavior of residual -algebras is studied. For a probability space (, , P) a new topology is introduced on the set of all -subalgebras. Necessary and sufficient conditions for the independence of events from the final -algebra are obtained in terms of mixing.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 8, pp. 1149–1152, August, 1992.     

On σ-images of Metric Spaces

In this paper the relation between the σ-images of metrical spaces and spaces with σ-locally finite cs-network, or spaces with σ-locally finite cs^*-network, or spaces with σ-locally finite sequence neighborhood network, or spaces with σ-locally finite sequence open network are established by use of σ-mapping.     

Correlation functions of gauged linear σ-model

This is the second paper in a series following Tian and Xu(2015), on the construction of a mathematical theory of the gauged linear σ-model(GLSM). In this paper, assuming the existence of virtual moduli cycles and their certain properties, we define the correlation function of GLSM for a fixed smooth rigidified r-spin curve.     

A compactness property of Dedekind σ-completef-rings

We prove that Dedekind -completef-rings are boundedly countably atomic compact in the language (+, –, ·,, , ). This means that whenever is a countable set of atomic formulae with parameters from some Dedekind -completef-ringA every finite subsystem of which admits a solution in some fixed productK of bounded closed intervals ofA, then admits a solution inK.Presented by M. Henriksen.     

On σ-semipermutable Subgroups of Finite Groups

Let σ = {σ_i|i ∈ I } be some partition of the set of all primes P, G a finite group andσ(G) = {σ_i |σ_i ∩π(G) = ?}. A set H of subgroups of G is said to be a complete Hall σ-set of G if every member = 1 of H is a Hall σ_i-subgroup of G for some σ_i ∈σ and H contains exactly one Hallσ_i-subgroup of G for every σ_i ∈σ(G). A subgroup H of G is said to be: σ-semipermutable in G with respect to H if H H_i~x= H_i~xH for all x ∈ G and all H_i ∈ H such that(|H|, |H_i|) = 1; σ-semipermutable in G if H is σ-semipermutable in G with respect to some complete Hall σ-set of G. We study the structure of G being based on the assumption that some subgroups of G are σ-semipermutable in G.     

Pseudoanalyticity of continuous functions with the σ-preservation of angles

The following theorem is proved: Every continuous function satisfying the conditionK is pseudo-analytic. The conditionK is a generalization of the Men'shov condition, well known in the theory of analytic functions.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 8, pp. 1051–1057, August, 1993.     

Atomic intersection of σ-fields and some of its consequences

Let ${(\Omega, \mathcal{F}, P)}$ be a probability space. For each ${\mathcal{G}\subset\mathcal{F}}$ , define ${\overline{\mathcal{G}}}$ as the σ-field generated by ${\mathcal{G}}$ and those sets ${F\in \mathcal{F}}$ satisfying ${P(F)\in\{0,1\}}$ . Conditions for P to be atomic on ${\cap_{i=1}^k\overline{\mathcal{A}_i}}$ , with ${\mathcal{A }_1,\ldots,\mathcal{A}_k\subset\mathcal{F}}$ sub-σ-fields, are given. Conditions for P to be 0-1-valued on ${\cap_{i=1}^k \overline{\mathcal{A}_i}}$ are given as well. These conditions are useful in various fields, including Gibbs sampling, iterated conditional expectations and the intersection property.     

Invariant σ-fields for a class of diffusions

Summary The invariant -field for a diffusion gives all bounded harmonic functions for the infinitesimal generator of that diffusion. We specify the invariant -field for a class of two dimensional diffusions and thereby obtain a representation for all bounded harmonic functions for the process. When the infinitesimal generator is radially symmetric we obtain the Martin boundary. This is used to find the invariant -field for the corresponding process.     

The Groups of Symmetric Genus σ ≤ 8

Let G be a finite group. The symmetric genus σ (G) is the minimum genus of any compact Riemann surface on which G acts faithfully as a group of automorphisms. Here we classify the groups of symmetric genus σ, for all values of σ such that 4 ≤ σ ≤ 8. In addition, we obtain some general results about the partial presentations that groups acting on surfaces must have. We show that a group with even genus and no “large order” elements in its Sylow 2-subgroup has restrictions on its Sylow 2-subgroup. As a consequence, we show that if G is a 2-group with positive symmetric genus, then σ(G) is odd. The software package MAGMA was employed to help with the calculations, and the MAGMA library of small groups was essential to the classification.