A group with <Emphasis Type="Italic">H</Emphasis>-Frobenius element of even order

We settle Question 10.61 in the Kourovka Notebook for the case where the order of an element a is even.Supported by RFBR grant No. 03-01-00356 and by the Krasnoyarsk Science Foundation, project 11F0202C.Translated from Algebra i Logika, Vol. 44, No. 1, pp. 70–80, January–February, 2005.     

Typical Frobenius coverings

A covering p from a Cayley graph Cay（G, X） onto another Cay（H, Y） is called typical Frobenius if G is a Frobenius group with H as a Frobenius complement and the map p ： G →H is a group epimorphism. In this paper, we emphasize on the typical Frobenius coverings of Cay（H, Y）. We show that any typical Frobenius covering Cay（G, X） of Cay（H, Y） can be derived from an epimorphism /from G to H which is determined by an automorphism f of H. If Cay（G, X1） and Cay（G, X2） are two isomorphic typical Frobenius coverings under a graph isomorphism Ф, some properties satisfied by Фare given.     

On Groups with Frobenius Elements

It is proved that group G contains an Abelian normal periodic complement to C_G(a²) if a is an H-Frobenius element a of order 4 of G. Mathematics Subject Classification (2000) 20E25.     

Fibred Frobenius theorem

We give a version of Frobenius Theorem for fibred manifolds whose proof is shorter than the “short proofs” of the classical Frobenius Theorem. In fact, what shortens the proof is the fibred form of the statement, since it permits an inductive process which is not possible from the standard statement.     

Are Biseparable Extensions Frobenius?

In Secion 1 we describe what is known of the extent to which a separable extension of unital associative rings is a Frobenius extension. A problem of this kind is suggested by asking if three algebraic axioms for finite Jones index subfactors are dependent. In Section 2 the problem in the title is formulated in terms of separable bimodules. In Section 3 we specialize the problem to ring extensions, noting that a biseparable extension is a two-sided finitely generated projective, split, separable extension. Some reductions of the problem are discussed and solutions in special cases are provided. In Section 4 various examples are provided of projective separable extensions that are neither finitely generated nor Frobenius and which give obstructions to weakening the hypotheses of the question in the title. In Section 5 we show that characterizations of the separable extensions among Frobenius extensions are special cases of a result for adjoint functors. Mathematics Subject Classifications (2000): 16L60, 16H05.     

Finite Groups all of Whose Second Maximal Subgroups are QTI-Subgroups

A subgroup H of a finite group G is called a QTI-subgroup if C _G (x) ≤ N _G (H) for any 1 ≠ x ∈ H. In this article, the finite groups all of whose second maximal subgroup are QTI-subgroups are classified.     

J正交矩阵的一些性质

给出了J正交矩阵的一些性质．     

The Structure of Some Groups with Finite H-Frobenius Elements

Question 10.61, set up by Sozutov in the Kourovka Notebook, is answered in the affirmative for all cases but |a|=3,5.     

Characterization of modular frobenius groups of special type

In this article, we first investigate the properties of modular Frobenius groups. Then, we consider the case that G' is a minimal normal subgroup of a modular Frobenius group G. We give the complete classification of G when G' as a modular Frobenius kernel has no more than four conjugacy classes in G.     

Givental symmetries of Frobenius manifolds and multi-component KP tau-functions

We establish a link between two different constructions of the action of the twisted loop group on the space of Frobenius structures. The first construction (due to Givental) describes the action of the twisted loop group on the partition functions of formal (axiomatic) Gromov-Witten theories. The explicit formulas for the corresponding tangent action were computed by Y.-P. Lee. The second construction (due to van de Leur) describes the action of the same group on the space of Frobenius structures via the multi-component KP hierarchies. Our main theorem states that the genus zero restriction of the Y.-P. Lee formulas coincides with the tangent van de Leur action.     

On Finite Simple Groups with the Set of Element Orders as in a Frobenius Group or a Double Frobenius Group

It is proved that a finite simple group with the set of element orders as in a Frobenius group (a double Frobenius group, respectively) is isomorphic to L₃(3) or U₃(3) (to U₃(3) or S₄(3), respectively).     

Representation of numbers by linear forms

The paper contains new theorems concerning the Frobenius problem, belonging to additive number theory, and using continued fractions. Translated fromMatematicheskie Zametki, Vol. 68, No. 2, pp. 210–216, August, 2000.     

Submersions via Projections

By writing the O'Neill tensors as derivatives of the natural projection one does not need the usual case distinctions any more and gets a much shorter list of basic equations. A short, induction free proof of the Frobenius theorem is a by-product.     

On additive semigroups starting parts

We present geometrical arguments suggesting that the part of the segment {0,1,…,N−1} covered by the additive semigroup generated by (a,b,c) between 0 and the Frobenius number N(a,b,c) should exceed λ V for some constant λ (which might be 1/3 or even more).