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### $±$ sign pattern matrices that allow orthogonality

Czechoslovak Mathematical Journal

A sign pattern $A$ is a $±$ sign pattern if $A$ has no zero entries. $A$ allows orthogonality if there exists a real orthogonal matrix $B$ whose sign pattern equals $A$. Some sufficient conditions are given for a sign pattern matrix to allow orthogonality, and a complete characterization is given for $±$ sign patterns with $n-1\le {N}_{-}\left(A\right)\le n+1$ to allow orthogonality.

### A Bruhat order for the class of $\left(0,1\right)$-matrices with row sum vector $R$ and column sum vector $S$.

ELA. The Electronic Journal of Linear Algebra [electronic only]

### A canonical directly infinite ring

Czechoslovak Mathematical Journal

Let $ℕ$ be the set of nonnegative integers and $ℤ$ the ring of integers. Let $ℬ$ be the ring of $N×N$ matrices over $ℤ$ generated by the following two matrices: one obtained from the identity matrix by shifting the ones one position to the right and the other one position down. This ring plays an important role in the study of directly finite rings. Calculation of invertible and idempotent elements of $ℬ$ yields that the subrings generated by them coincide. This subring is the sum of the ideal $ℱ$ consisting of...

### A computation of positive one-peak posets that are Tits-sincere

Colloquium Mathematicae

A complete list of positive Tits-sincere one-peak posets is provided by applying combinatorial algorithms and computer calculations using Maple and Python. The problem whether any square integer matrix $A\in ₙ\left(ℤ\right)$ is ℤ-congruent to its transpose ${A}^{tr}$ is also discussed. An affirmative answer is given for the incidence matrices ${C}_{I}$ and the Tits matrices $C{̂}_{I}$ of positive one-peak posets I.

### A Factorization of an Integral 2 x 2 Matrix Via a Rational Method.

Monatshefte für Mathematik

### A matrix inequality for Möbius functions.

JIPAM. Journal of Inequalities in Pure &amp; Applied Mathematics [electronic only]

### A note on consecutive ones in a binary matrix.

APPS. Applied Sciences

### A note on Fibonacci matrices of even degree.

International Journal of Mathematics and Mathematical Sciences

### A note on indecomposability of Boolean matrices

Kragujevac Journal of Mathematics

### A note on the Hankel transform of the central binomial coefficients.

Journal of Integer Sequences [electronic only]

### A problem on $0-1$ matrices

Compositio Mathematica

### An analysis of GCD and LCM matrices via the $LD{L}^{T}$-factorization.

ELA. The Electronic Journal of Linear Algebra [electronic only]

### An Example on Strong Equivalence of Positive Integral Matrices.

Monatshefte für Mathematik

### An upper bound for the ${\ell }_{p}$ norm of a gcd-related matrix.

Journal of Inequalities and Applications [electronic only]

### Bounds on the coefficients of the characteristic and minimal polynomials.

JIPAM. Journal of Inequalities in Pure &amp; Applied Mathematics [electronic only]

### Certain matrices related to Fibonacci sequence having recursive entries.

ELA. The Electronic Journal of Linear Algebra [electronic only]

### Characterisation of some sparse binary sequential arrays.

Aequationes mathematicae

Integers

### Complete residue systems in the ring of matrices of rational integers.

International Journal of Mathematics and Mathematical Sciences

### Concerning row operations on systems of linear equations with integral coefficients.

International Journal of Mathematics and Mathematical Sciences

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