⊕-Cofinitely Supplemented Modules

Let R be a ring and M a right R-module. M is called -cofinitely supplemented if every submodule N of M with M/N finitely generated has a supplement that is a direct summand of M. In this paper various properties of the -cofinitely supplemented modules are given. It is shown that (1) Arbitrary direct sum of -cofinitely supplemented modules is -cofinitely supplemented. (2) A ring R is semiperfect if and only if every free R-module is -cofinitely supplemented. In addition, if M has the summand sum property, then M is -cofinitely supplemented iff every maximal submodule has a supplement that is a direct summand of M.     

Unusual interactions of (1/2, 0) ⊕ (0, 1/2) particles

We continue to study the ‘fermion — 4-vector potential’ interactions in the framework of the McLennan-Case construct which is a reformulation of the Majorana theory of the neutrino. This theory is shown after applying Majorana-likeanzatzen to give rise to appearance of unusual terms as σ [A×A^*], which were recently discussed in non-linear optics.     

On strongly ⊕-supplemented modules

Strongly ⊕-supplemented and strongly cofinitely ⊕-supplemented modules are defined and some properties of strongly ⊕-supplemented and strongly cofinitely ⊕-supplemented modules are investigated. Let R be a ring. Then every R-module is strongly ⊕-supplemented if and only if R is perfect. The finite direct sum of ⊕-supplemented modules is ⊕-supplemented. However, this is not true for strongly ⊕-supplemented modules. Any direct sum of cofinitely ⊕-supplemented modules is cofinitely ⊕-supplemented but this is not true for strongly cofinitely ⊕-supplemented modules. We also prove that a supplemented module is strongly ⊕-supplemented if and only if every supplement submodule lies above a direct summand.     

关于(X⊕Y)_1的凸性

本文绘出ｋ－严格凸、（局部）ｋ一致圆定义的几个等价形式．利用等价形式,讨论了（Ｘ(Ｘ）１的ｋ－严格凸及（局部）ｋ一致圆性．     

When ∏ is Isomorphic to ⊕

For a category , we investigate the problem of when the coproduct ⊕ and the product functor ∏ from  ^I to  are isomorphic for a fixed set I, or, equivalently, when the two functors are Frobenius functors. We show that for an Ab category  this happens if and only if the set I is finite (and even in a much general case, if there is a morphism in  that is invertible with respect to addition). However, we show that ⊕ and ∏ are always isomorphic on a suitable subcategory of  ^I which is isomorphic to  ^I but is not a full subcategory. If  is only a preadditive category, then we give an example that shows that the two functors can be isomorphic for infinite sets I. For the module category case, we provide a different proof to display an interesting connection to the notion of Frobenius corings.     

On Non-M-Cosingular Completely ⊕-Supplemented Modules

In this paper, it is shown that any non--cosingular -supplemented module is if and only if has the summand intersection property. Let be any module such that has a coclosure in . Then we prove that is (completely) -supplemented if and only if for some submodule of such that and both are (completely) -supplemented.     

Wakimoto modules for twisted multi-loop algebra of type A1 × A1

We construct a class of modules for the twisted multi-loop algebra of type A1×A1 by applying Wakimoto free bosonic realization. We also discuss the structures and the irreducibility of the Fock space.     

A simple proof of Ramanujan’s summation of the1ψ1

A simple proof by functional equations is given for Ramanujan’s₁ ψ ₁ sum. Ramanujan’s sum is a useful extension of Jacobi's triple product formula, and has recently become important in the treatment of certain orthogonal polynomials defined by basic hypergeometric series.     

Complex Lorentz rotations on vectors⊕pseudovectors

We study the complex structure of the space of vectors and pseudovectors Λ≡ ≡ Λ₁ ⊕ Λ₃ arising from the properties of the Hodge duality in 4-dimensional spacetimes. This structure appears naturally in the framework of its real Clifford geometric algebraCl _1,3 orCl _3,1, in which the Hodge duality is the simple multiplication by the volume unit ∈. Interpreting the linear combination of a scalar and a pseudoscalar α+β∈ as a complex number (Λ₀ ⊕ Λ₄ ⋍ ℂ), the odd subspace Λ_ ∈Cl is a left/right complex linear space, previously studied by Sobczyk. From the real metric definingCl, Λ_ inherits a natural complex bilinear normN(a). Corresponding to this norm there is the group of complex Lorentz rotations Spin_1,3 (ℂ), for which we find a formulation using exclusively the real algebraCl. We discuss its behaviour in some examples and find expressions for different decompositions into real and selfdual, real and anti-selfdual, and real and pure imaginary angle rotations. We finally apply our results to the implementation of the rotations corresponding to Euclidean and null signatures inside the real Lorentzian Clifford algebraCl.     

关于(X⊕Y)1的凸性

本文给出k-严格凸、(局部)k一致圆定义的几个等价形式.利用等价形式,讨论了(X⊕Y)₁的k-严格凸及(局部)k一致圆性.     

Some remarks concerning matrices of the form A–A′, A−1A′

Matrices and operators of the formA ^–1 A ^* have received a certain amount of attention in recent years. Here some of the literature is surveyed and the caseA ^–1 A is studied for complex matrices withA denoting the transpose ofA. A generalization ofA ^–1 A is introduced.

---

Zusammenfassung Matrizen und Operatoren, die in der FormA ^–1 A ^* ausgedrückt werden können, sind in den letzten Jahren häufig studiert worden. Hier wird ein Ueberblick über Teil der relevanten Literatur gegeben und auch der FallA ^–1 A für komplexe Matrizen studiert, wobeiA die Transponierte vonA ist. Es wird auch eine Verallgemeinerung vonA ^–1 A eingeführt.

---

---

Dedicated to Eduard Stiefel by a long time admirer     

Rings whose cyclic modules are lifting and ⊕-supplemented

It is proved that a semiperfect module is lifting if and only if it has a projective cover preserving direct summands. Three corollaries are obtained: (1) every cyclic module over a ring R is lifting if and only if every cyclic R-module has a projective cover preserving direct summands; (2) a ring R is artinian serial with Jacobson radical square-zero if and only if every (2-generated) R-module has a projective cover preserving direct summands; (3) a ring R is a right (semi-)perfect ring if and only if (cyclic) lifting R-module has a projective cover preserving direct summands, if and only if every (cyclic) R-module having a projective cover preserving direct summands is lifting. It is also proved that every cyclic module over a ring R is ⊕-supplemented if and only if every cyclic R-module is a direct sum of local modules. Consequently, a ring R is artinian serial if and only if every left and right R-module is a direct sum of local modules.     

On the size of the set A(A + 1)

Let F _p be the field of a prime order p. For a subset A ì F_p{A \subset F_p} we consider the product set A(A + 1). This set is an image of A ×  A under the polynomial mapping f(x, y) = xy +  x : F _p ×  F _p → F _p . In the present note we show that if |A| <  p ^1/2, then

矩阵方程X=Q+A~* (I_m⊕ X-C)~(-1) A的Hermitian正定解

研究了一类来源于插值理论的非线性矩阵方程.利用Kronecker积的性质以及Banach空间单调有界序列收敛原理证明了此类方程正定解的存在唯一性.另外也给出了此方程正定解的范围.     

A Kind of GC~1 Blending of Triangular B ézier Patches

ＡＫｉｎｄｏｆＧＣ１ＢｌｅｎｄｉｎｇｏｆＴｒｉａｎｇｕｌａｒＢ︺ｚｉｅｒＰａｔｃｈｅｓ＊）ＷａｎｇＸｉａｎｇｈａｉ（王相海）（ＮａｔｉｏｎａｌＬａｂｏｒａｔｏｒｙｏｆＳｙｍｂｏｌｉｃＣｏｍｐｕｔａｔｉｏｎａｎｄＫｎｏｗｌｅｄｇｅＥｎｇｉｎｅｅｒｉｎｇ...     

A Graceful Numbering of A Class of Graphs

The graphs considered here are finite, undirected and simple. The sets ofvertices and edges of a graph G are denoted by V(G) and E(G), respectively.A graph G is called to be numbered if each vertex υ of G is assigned a nonnegative integer φ(υ), and each edge {u,υ} is assigned the absolute value of thedifference of the numbers at its endpoints, i.e.,|φ(u)-φ(υ)|.     

A Characterization of l + 1(Γ)

In this article we give necessary and sufficient conditions in order a closed cone of a Banach space E to be isomorphic to the positive cone l ₁ ⁺(Γ) of an l ₁(Γ) space. This problem has applications in the theory of Banach spaces as in the characterization of reflexive spaces and also on the problem of the embeddability of 1in Banach spaces.