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Recursive matrices are ubiquitous in combinatorics, which have been extensively studied. We focus on the study of the sums of $2times 2$ minors of certain recursive matrices, the alternating sums of their $2times 2$ minors, and the sums of their $2times 2$ permanents. We obtain some combinatorial identities related to these sums, which generalized the work of Sun and Ma in [{it Electron. J. Combin. 2014}] and [{it European J. Combin. 2014}]. With the help of the computer algebra package {tt HolonomicFunctions}, we further get some new identities involving Narayana polynomials.
Let $Q_{n,d}$ denote the random combinatorial matrix whose rows are independent of one another and such that each row is sampled uniformly at random from the subset of vectors in ${0,1}^n$ having precisely $d$ entries equal to $1$. We present a short
The main result of this paper is the decidability of the membership problem for $2times 2$ nonsingular integer matrices. Namely, we will construct the first algorithm that for any nonsingular $2times 2$ integer matrices $M_1,dots,M_n$ and $M$ decides
A (q,k,t)-design matrix is an m x n matrix whose pattern of zeros/non-zeros satisfies the following design-like condition: each row has at most q non-zeros, each column has at least k non-zeros and the supports of every two columns intersect in at mo
Let $mathcal S$ be a single condition Schubert variety with an arbitrary number of strata. Recently, an explicit description of the summands involved in the decomposition theorem applied to such a variety has been obtained in a paper of the second au
In this paper we study products of quadratic residues modulo odd primes and prove some identities involving quadratic residues. For instance, let $p$ be an odd prime. We prove that if $pequiv5pmod8$, then $$prod_{0<x<p/2,(frac{x}{p})=1}xequiv(-1)^{1+