A Realization of Quantum Groups via Product Valued Quivers

Let C be the symmetrizable generalized Cartan matrix associated to a valued quiver \(\overset{\rightarrow}{\Gamma}\). We show that the whole quantum group associated to C can be realized from the abelian category of the representations of the product valued quiver \(\overset{\rightarrow}{\Gamma^{\pm}}\) of \(\overset{\rightarrow}{\Gamma}\) with the Kronecker quiver. This method can be used to realize the whole generalized Kac–Moody Lie algebra associated to C, as discussed in Li and Lin (submitted for publication, arXiv:math/0610448).     

On the cardinalities of Kronecker quiver Grassmannians

We deduce using the Ringel?CHall algebra approach explicit formulas for the cardinalities of some Grassmannians over a finite field associated to the Kronecker quiver. We realize in this way a quantification of the formulas obtained by Caldero and Zelevinsky for the Euler characteristics of these Grassmannians. Finally we present a recursive algorithm for computing the cardinality of every Kronecker quiver Grassmannian over a finite field.     

Connectedness of Kronecker sum and partial Kronecker row sum of designs

In this paper we discuss connectedness of a design which is a Kronecker sum or a partial Kronecker row sum of any two equi-replicate and equi-block size designs.     

Generic variables in acyclic cluster algebras

Let Q be an acyclic quiver. We introduce the notion of generic variables for the coefficient-free acyclic cluster algebra A(Q). We prove that the set G(Q) of generic variables contains naturally the set M(Q) of cluster monomials in A(Q) and that these two sets coincide if and only if Q is a Dynkin quiver. We establish multiplicative properties of these generic variables analogous to multiplicative properties of Lusztig’s dual semicanonical basis. This allows to compute explicitly the generic variables when Q is a quiver of affine type. When Q is the Kronecker quiver, the set G(Q) is a Z-basis of A(Q) and this basis is compared to Sherman-Zelevinsky and Caldero-Zelevinsky bases.     

Sequences of reflection functors and the preprojective component of a valued quiver

This paper concerns preprojective representations of a finite connected valued quiver without oriented cycles. For each such representation, an explicit formula in terms of the geometry of the quiver gives a unique, up to a certain equivalence, shortest (+)-admissible sequence such that the corresponding composition of reflection functors annihilates the representation. The set of equivalence classes of the above sequences is a partially ordered set that contains a great deal of information about the preprojective component of the Auslander-Reiten quiver. The results apply to the study of reduced words in the Weyl group associated with an indecomposable symmetrizable generalized Cartan matrix.     

Quivers and Poisson structures

We produce natural quadratic Poisson structures on moduli spaces of representations of quivers. In particular, we study a natural Poisson structure for the generalised Kronecker quiver with 3 arrows.     

Kronecker Product of Two-dimensional Arrays

Kronecker sequences constructed from short sequences are good sequences for spread spectrum communication systems. In this paper we study a similar problem for two-dimensional arrays, and we determine the linear complexity of the Kronecker product of two arrays, Our result shows that similar good property on linear complexity holds for Kronecker product of arrays.     

对角占优矩阵直积的注记

将对角占优矩阵的性质与矩阵的直积结合起来,给出了两矩阵的直积是对角占优矩阵的一些充分和必要条件,推广了近期的一些结果.最后用相应的数值例子说明了所得结果的有效性.     

Tree modules of the generalised Kronecker quiver

For coprime roots certain torus fixed points of the Kronecker moduli space are indecomposable tree modules. They are indecomposable representations of the regular m-tree and can be glued in order to get stable torus fixed points for every coprime root. Using their stability and the reflection functor we show that for arbitrary roots there exist indecomposable tree modules of the Kronecker quiver as factor modules of these torus fixed points.     

Strictly positive definite functions on the unit circle

We study strictly positive definite functions on the unit circle in the Euclidean space of dimension two. We develop several conditions pertaining to the determination of such functions. The major result is obtained by considering the set of real numbers as a vector space over the field of rational numbers and then applying the Kronecker approximation theorem and Weyl's criterion on equidistributions.

     

On the Euler characteristic of Kronecker moduli spaces

Combining the MPS degeneration formula for the Poincaré polynomial of moduli spaces of stable quiver representations and localization theory, it turns that the determination of the Euler characteristic of these moduli spaces reduces to a combinatorial problem of counting certain trees. We use this fact in order to obtain an upper bound for the Euler characteristic in the case of the Kronecker quiver. We also derive a formula for the Euler characteristic of some of the moduli spaces appearing in the MPS degeneration formula.     

Correction to critical pairs of matrices for the degree of the minimal polynomial of the kronecker sum

We present a correction to the main theorem in the article "Critical Pairs of Matrices for the Degree of the Minimal Polynomial of the Kronecker Sum", Volume 42 (1997) pages 73-88.     

On the second eigenvalue of matrices associated with TCP

We consider a convex combination of matrices that arise in the study of communication networks and the corresponding convex combination of Kronecker squares of these matrices. We show that the spectrum of the first convex combination is contained in the spectrum of the second set and that the second largest eigenvalues coincide.     

对角占优矩阵直积的一些性质

给出了对角占优矩阵直积的一些对角占优性质以及∞-范数估计式.     

矩阵的分块Kronecker积

为了构造适应于复杂的矩阵计算的程序,在分块矩阵与Kronecker积的基础上提出一类新的矩阵运算方式,称之为矩阵的分块Kronecker积.首先研究了这种运算的性质及计算机实现的过程,进一步讨论了的这类运算在实际中的应用,最后提出进一步可研究的问题.     

几类积图的团染色数

设G=（VE）为简单图,V和E分别表示图的点集和边集．图G的一个k-团染色是指点集V到色集{1,2,…,k）的一个映射,使得G的每个至少含两个点的极大团都至少有两种颜色．分别给出了任意两个图的团色数与它们通过笛卡尔积、Kronecker积、强直积或字典积运算后得到的积图的团色数之间的关系．     

Critical pairs of matrices for the degree of the minimal polynomial of the Kronecker sum

In [4] Dias da Silva and Hamidoune obtained a lower bound for the degree of the minimal polynomial of the Kronecker sum of two matrices in terms of the degrees of the minimal polynomials of the matrices. We determine the pairs of matrices for which this bound is reached.     

亚正定矩阵的Kronecker积

研究亚正定矩阵kronecker积的亚正定性,得到了一个充要条件,同时得到Hadamard积亚正定性的一个充要条件.     

Kronecker乘积图的超连通性(英文)

设G1和G2是两个连通图,则G1和G2的Kronecker积G1×G2定义如下:V(G1×G2)=V(G1)×V(G2),E(G1×G2)={(u1,v1)(u2,v2):u1u2∈E(G1),v1v2∈E(G2)}.我们证明了G×Kn(n≥4)超连通图当且仅当κ(G)n>δ(G)(n 1),其中G是任意的连通图,Kn是n阶完全图.进一步我们证明了对任意阶至少为3的连通图G,如果κ(G)=δ(G),则G×Kn(n≥3)超连通图.这个结果加强了郭利涛等人的结果.     

Applications of the Frobenius Formulas for the Characters of the Symmetric Group and the Hecke Algebras of Type A

We give a simple combinatorial proof of Ram's rule for computing the characters of the Hecke Algebra. We also establish a relationship between the characters of the Hecke algebra and the Kronecker product of two irreducible representations of the Symmetric Group which allows us to give new combinatorial interpretations to the Kronecker product of two Schur functions evaluated at a Schur function of hook shape or a two row shape. We also give a formula for the regular representation of the Hecke algebra.