加权Motzkin序列的Hankel行列式

基于经典的Motzkin路引入了一类新的加权Motzkin路的定义,用这种路给出了一类指数型Riordan矩阵的组合解释,得到了相应的Riordan矩阵第0列元素(加权Motzkin序列)的加法公式.作为应用,得到了一类加权Motzkin序列的Hankel行列式的计算方法.     

加权Motzkin数的恒等式及其组合意义

利用Riordan矩阵的A序列和Z序列得到了水平步、上步和下步加权的Motzkin路和Riordan路的矩阵表达式,并利用拉格朗日反演公式计算得出其一般元.最后证明了水平步、上步和下步加权分别为α,β,γ的Motzkin数的递推关系式.     

Riordan矩阵与广义的Pell路

利用Riordan矩阵的A-矩阵得到几类广义Pell路的Riordan矩阵表达式,证明了这些矩阵的行和满足的递推关系,从而给出满足这些递推关系的序列的组合意义.最后将这些格路限制在直线x = y的上方,得出相应的Riordan矩阵表达式的一般形式.     

加权广义的Schröder路的计数

考虑具有四种步型的格路,称之为加权广义的Schr?der路.利用Riordan矩阵研究了加权广义Schr?der路的计数问题,得到了 Schr?der数几种新的组合解释.     

Riordan 矩阵的$(m,r,s)$-Halves

Riordan矩阵的垂直一半和水平一半已经被许多学者分别研究过.本文给出了Riordan矩阵的$(m,r,s)$-halves的定义.利用此定义能够统一的讨论Riordan矩阵的垂直一半和水平一半.作为应用,通过对Pascal和Delannoy矩阵的$(m,r,s)$-halves的研究,可以得到了一些与Fibonacci, Pell和Jacobsthal序列相关的等式.     

从Riordan阵到广义Riordan群及有关问题

简要给出关于Riordan阵与Riordan群两个重要概念的历史性注记,指出早两年相关文献所论广义Stirling数偶与相应互逆矩阵已包含有Riordan阵与互逆Riordan矩阵的概念.扼要介绍2014年发表的一种新扩充,以及需要进一步研究的若干相关问题.     

峰严格递增的Dyck路的计数

本文考虑了由最高峰的高度为m,并且峰的高度沿着Dyck路严格递增的所有Dyck路组成的集合,即集合Dm的子集的计数问题．利用双射、生成树以及Riordan阵的方法来对集合Dm的一些子集进行计数,得到了一些以经典的序列如Catalan数、Narayana数、Motzkin数、Fibonacci数、Schroder数以及第一类无符号Stirling数来计数的组合结构．特别地,我们给出了两个新的Catalan结构,它们并没有明显地出现在Stanley关于Catalan结构的列表中．     

广义模糊幂零矩阵

路代数是加法幂等的半环,它包括了布尔代数,模糊代数,分配格及斜坡.因此布尔矩阵,模糊矩阵,格矩阵及斜矩阵都是路代数上的典型矩阵.广义模糊幂零矩阵指的就是路代数上的幂零矩阵.在2010年,Tan研究了路代数上矩阵的幂零性.在Tan的基础上继续讨论了路代数上幂零矩阵的幂零指数.     

环Z/p~kZ上矩阵广义逆的拓展

设R=Z/pkZ(其中k>1,p是一个奇素数),A是R上一个给定的可相似对角化的n阶矩阵.利用组合方法和有限局部环上的矩阵方法,讨论了矩阵A的拓展广义逆,得到了矩阵A的拓展广义逆存在的充要条件和一些的计数定理.     

广义酉矩阵与广义Hermite矩阵的张量积与诱导矩阵

本文研究了有限个广义酉矩阵与广义(反)Hermite矩阵的张量积和诱导矩阵.利用矩阵的张量积和诱导矩阵的性质,得到了它的张量积和诱导矩阵仍为广义酉矩阵与广义(反)Hermite矩阵.     

P分之一Riordan矩阵及恒等式构造

For an integer p≥2 we construct vertical and horizontal one-pth Riordan arrays from a Riordan array.When p=2 one-pth Riordan arrays are reduced to well known half Riordan arrays.The generating functions of the A-sequences of vertical and horizontal one-pth Riordan arrays are found.The vertical and horizontal one-pth Riordan arrays provide an approach to construct many identities.They can also be used to verify some well known identities readily.     

Riordan arrays associated with Laurent series and generalized Sheffer-type groups

A relationship between a pair of Laurent series and Riordan arrays is formulated. In addition, a type of generalized Sheffer groups is defined by using Riordan arrays with respect to power series with non-zero coefficients. The isomorphism between a generalized Sheffer group and the group of the Riordan arrays associated with Laurent series is established. Furthermore, Appell, associated, Bell, and hitting-time subgroups of the groups are defined and discussed. A relationship between the generalized Sheffer groups with respect to different type of power series is presented. The equivalence of the defined Riordan array pairs and generalized Stirling number pairs is given. A type of inverse relations of various series is constructed by using pairs of Riordan arrays. Finally, several applications involving various arrays, polynomial sequences, special formulas and identities are also presented as illustrative examples.     

A generalization of Lucas polynomial sequence

In this paper, we obtain a generalized Lucas polynomial sequence from the lattice paths for the Delannoy numbers by allowing weights on the steps (1,0),(0,1) and (1,1). These weighted lattice paths lead us to a combinatorial interpretation for such a Lucas polynomial sequence. The concept of Riordan arrays is extensively used throughout this paper.     

Limits of areas under lattice paths

We consider sequences of polynomials which count lattice paths by area. In some cases the reversed polynomials approach a formal power series as the length of the paths tend to infinity. We find the limiting series for generalized Schröder, Motzkin, and Catalan paths. The limiting series for Schröder paths and their generalizations are shown to count partitions with restrictions on the multiplicities of odd parts and no restrictions on even parts. The limiting series for generalized Motzkin and Catalan paths are shown to count generalized Frobenius partitions and some related arrays.     

Half Inverse Riordan Arrays and Their Related Vertical Recurrence Relation

We discuss two different procedures to study the half Riordan arrays and their inverses. One of the procedures shows that every Riordan array is the half Riordan array of a unique Riordan array. It is well known that every Riordan array has its half Riordan array. Therefore, this paper answers the converse question: Is every Riordan array the half Riordan array of some Riordan arrays? In addition, this paper shows that the vertical recurrence relation of the column entries of the half Riordan array is equivalent to the horizontal recurrence relation of the original Riordan array''s row entries.     

Some matrix identities on colored Motzkin paths

Merlini and Sprugnoli (2017) give both an algebraic and a combinatorial proof for an identity proposed by Louis Shapiro by using Riordan arrays and a particular model of lattice paths. In this paper, we revisit the identity and emphasize the use of colored partial Motzkin paths as appropriate tool. By using colored Motzkin paths with weight defined according to the height of its last point, we can generalize the identity in several ways. These identities allow us to move from Fibonacci polynomials, Lucas polynomials, and Chebyshev polynomials, to the polynomials of the form ${(z+b)}^n$.     

Generalized Riordan arrays

In this paper, we generalize the concept of Riordan array. A generalized Riordan array with respect to c_n is an infinite, lower triangular array determined by the pair (g(t),f(t)) and has the generic element d_n,k=[tⁿ/c_n]g(t)(f(t))^k/c_k, where c_n is a fixed sequence of non-zero constants with c₀=1.We demonstrate that the generalized Riordan arrays have similar properties to those of the classical Riordan arrays. Based on the definition, the iteration matrices related to the Bell polynomials are special cases of the generalized Riordan arrays and the set of iteration matrices is a subgroup of the Riordan group. We also study the relationships between the generalized Riordan arrays and the Sheffer sequences and show that the Riordan group and the group of Sheffer sequences are isomorphic. From the Sheffer sequences, many special Riordan arrays are obtained. Additionally, we investigate the recurrence relations satisfied by the elements of the Riordan arrays. Based on one of the recurrences, some matrix factorizations satisfied by the Riordan arrays are presented. Finally, we give two applications of the Riordan arrays, including the inverse relations problem and the connection constants problem.     

Generalized harmonic numbers with Riordan arrays

By observing that the infinite triangle obtained from some generalized harmonic numbers follows a Riordan array, we obtain very simple connections between the Stirling numbers of both kinds and other generalized harmonic numbers. Further, we suggest that Riordan arrays associated with such generalized harmonic numbers allow us to find new generating functions of many combinatorial sums and many generalized harmonic number identities.     

Riordan paths and derangements

Riordan paths are Motzkin paths without horizontal steps on the x-axis. We establish a correspondence between Riordan paths and -avoiding derangements. We also present a combinatorial proof of a recurrence relation for the Riordan numbers in the spirit of the Foata-Zeilberger proof of a recurrence relation on the Schröder numbers.