Regular polygons with primitive connected theories

We study the monoids S over which the class of all regular S-polygons is axiomatizable and primitive connected. We prove that the axiomatizable class of all regular S-polygons is primitive connected if and only if the semigroup R is a rectangular band of groups and R = eR for some idempotent e ∈ R, where _S R is the inclusion maximal regular subpolygon in the S-polygon _S S.     

Polygons with primitive normal and additive theories

Previously, primitive normal, primitive connected, and additive theories of S-polygons were studied. In particular, it was proved that the class of all S-polygons is primitive normal iff S is a linearly ordered monoid. The present paper is a continuation of this research. Here, Spolygons with primitive normal, additive, and antiadditive theories are described in the language of a primitive equivalence structure. It is shown that the class of all S-polygons is antiadditive only for a linearly ordered monoid S, that is, this class is antiadditive iff it is primitive normal.     

Projective S-acts and Exact Functors

Let S be a semigroup. In this paper, projective S-acts and exact sequences in S-Act are studied. It is shown that, for a unitary S-act P, the functor Hom(P, –) is exact if and only if P Se for some idempotent e S.The research was supported by the National Natural Science Foundation of China.1991 Mathematics Subject Classification: 20M50     

Definibility in normal theories

This paper initiates an investigation which seeks to explain elementary definability as the classical results of mathematicallogic (the completeness, compactness and Löwenheim-Skolem theorems) explain elementary logical consequence. The theorems of Beth and Svenonius are basic in this approach and introduce automorphism groups as a means of studying these problems. It is shown that for a complete theoryT, the definability relation of Beth (or Svenonius) yields an upper semi-lattice whose elements (concepts) are interdefinable formulas ofT (formulas having equal automorphism groups in all models ofT). It is shown that there are countable modelsA ofT such that two formulae are distinct (not interdefinable) inT if and only if they are distinct (have different automorphism groups) inA. The notion of a concepth being normal in a theoryT is introduced. Here the upper semi-lattice of all concepts which defineh is proved to be a finite lattice—anti-isomorphic to the lattice of subgroups of the corresponding automorphism group. Connections with the Galois theory of fields are discussed.     

Existence of primitive normal pairs with one prescribed trace over finite fields

Designs, Codes and Cryptography - Given $$m, n, qin mathbb {N}$$ such that q is a prime power and $$mge 3$$ , $$ain mathbb {F}_q$$ , we establish a sufficient condition for the existence of a...     

A generalization of the primitive normal basis theorem

The primitive normal basis theorem asks whether every finite field extension has a primitive normal basis of this extension. The proof of this problem has recently been completed by Lenstra and Schoof (1987) [6], and another proof is given by Cohen and Huczynska (2003) [3]. We present a more general result, where the primitive element generating a normal basis is replaced by a primitive element generating the finite Carlitz module. Such generators always exist except for finitely many cases which might not exist.     

Regular and normal closure operators and categorical compactness for groups

For a class of groupsF, closed under formation of subgroups and products, we call a subgroupA of a groupG F-regular provided there are two homomorphismsf, g: G » F, withF F, so thatA = {x G |f(x) =g(x)}.A is calledF-normal providedA is normal inG andG/A F. For an arbitrary subgroupA ofG, theF-regular (respectively,F-normal) closure ofA inG is the intersection of allF-regular (respectively,F-normal) subgroups ofG containingA. This process gives rise to two well behaved idempotent closure operators.A groupG is calledF-regular (respectively,F-normal) compact provided for every groupH, andF-regular (respectively,F-normal) subgroupA ofG × H, ₂(A) is anF-regular (respectively,F-normal) subgroup ofH. This generalizes the well known Kuratowski-Mrówka theorem for topological compactness.In this paper, theF-regular compact andF-normal compact groups are characterized for the classesF consisting of: all torsion-free groups, allR-groups, and all torsion-free abelian groups. In doing so, new classes of groups having nice properties are introduced about which little is known.     

Observations on primitive,normal, and subnormal elements of field extensions

Let B ₁ and B ₂ be disjoint separable algebraic extensions of a field F, and let B = B ₁ B ₂ be their composite. Let α ₁ be an element of B ₁ and α ₂ be an element of B ₂. Suppose α ₁ and α ₂ are primitive (resp. normal, resp. subnormal). We investigate the question of when α ₁ + α ₂ and α ₁ α ₂ are necessarily primitive (resp. normal, resp. subnormal) elements of B. (A normal element of a Galois extension is defined to be one that is part of a normal basis, and a subnormal element is defined analogously for a non-Galois extension).     

Regular Homomorphisms and Regular Maps

Regular homomorphisms of oriented maps essentially arise from a factorization by a subgroup of automorphisms. This kind of map homomorphism is studied in detail, and generalized to the case when the induced homomorphism of the underlying graphs is not valency preserving. Reconstruction is treated by means of voltage assignments on angles, a natural extension of the common assignments on darts. Lifting and projecting groups of automorphisms along regular homomorphisms is studied in some detail. Finally, the split-extension structure of lifted groups is analysed.     

On the existence of primitive completely normal bases of finite fields

Let ${\mathbb{F}}_q$ be the finite field of characteristic p with q elements and ${\mathbb{F}}_{q^n}$ its extension of degree n. We prove that there exists a primitive element of ${\mathbb{F}}_{q^n}$ that produces a completely normal basis of ${\mathbb{F}}_{q^n}$ over ${\mathbb{F}}_q$, provided that $n=p^{?}m$ with $(m,p)=1$ and $q>m$.     

正则关系与完全正则空间

借助于关系的某些代数性质刻画拓扑空间的完全正则性,证明了拓扑空间是完全正则的当且仅当其闭集与开集之间存在满足一定简单条件的正则关系,有限正则关系或广义有限正则关系.     

Regular spaces with symmetries

Regular spaces with symmetries are manifolds with a multiplication that satisfies certain conditions. The concepts of translation group and general triple system of a regular space with symmetries are introduced and studied.Translated from Matematicheskie Zametki, Vol. 14, No. 1, pp. 113–120, July, 1973.     

Regular Semigroups with Inverse Transversals

Let C be a semiband with an inverse transversal . In [7], G.T. Song and F.L. Zhu construct a fundamental regular semigroup with an inverse transversal . is isomorphic to a subsemigroup of the Hall semigroup of C but it is easier to handle. Its elements are partial transformations, and the operation-although not the usual composition-is defined by means of composition. Any full regular subsemigroup T of is a fundamental regular semigroup with inverse transversal . Moreover, any regular semigroup S with an inverse transversal is proved to be an idempotent-separating coextension of a full regular subsemigroup T of some . By means of a full regular subsemigroup T of some and by means of an inverse semigroup K satisfying some conditions, in this paper, we construct a regular semigroup with inverse transversal such that is isomorphic to K and to T. Furthermore, it is proved that if S is a regular semigroup with an inverse transversal then S can be constructed from the corresponding T and from in this way.     

Prime and primitive algebras with prescribed growth types

Bartholdi and Smoktunowicz constructed in 2014 finitely generated monomial algebras with prescribed sufficiently fast growth types. We show that their construction need not result in a prime algebra, but it can be modified to provide prime algebras without further limitations on the growth type.Moreover, using a construction of an inverse system of monomial ideals which arise from this construction, we are able to further construct finitely generated primitive algebras without further limitations on the growth type.Then, inspired by Zelmanov’s example in 1979, we show how our prime algebras can be constructed such that they contain non-zero locally nilpotent ideals; this is the very opposite of the primitive constructions.