Article
Keywords:
meet-closed set; greatest-type lower; incidence function; determinant; nonsingularity
Summary:
Let $S=\lbrace x_1,\dots ,x_n\rbrace $ be a finite subset of a partially ordered set $P$. Let $f$ be an incidence function of $P$. Let $[f(x_i\wedge x_j)]$ denote the $n\times n$ matrix having $f$ evaluated at the meet $x_i\wedge x_j$ of $x_i$ and $x_j$ as its $i,j$-entry and $[f(x_i\vee x_j)]$ denote the $n\times n$ matrix having $f$ evaluated at the join $x_i\vee x_j$ of $x_i$ and $x_j$ as its $i,j$-entry. The set $S$ is said to be meet-closed if $x_i\wedge x_j\in S$ for all $1\le i,j\le n$. In this paper we get explicit combinatorial formulas for the determinants of matrices $[f(x_i\wedge x_j)]$ and $[f(x_i\vee x_j)]$ on any meet-closed set $S$. We also obtain necessary and sufficient conditions for the matrices $f(x_i\wedge x_j)]$ and $[f(x_i\vee x_j)]$ on any meet-closed set $S$ to be nonsingular. Finally, we give some number-theoretic applications.
References:
[2] S. Beslin, S. Ligh:
Greatest common divisor matrices. Linear Algebra Appl. 118 (1989), 69–76.
MR 0995366
[6] S. Hong:
LCM matrix on an $r$-fold gcd-closed set. J. Sichuan Univ., Nat. Sci. Ed. 33 (1996), 650–657.
MR 1440627 |
Zbl 0869.11021
[8] S. Hong:
On the factorization of LCM matrices on gcd-closed sets. Linear Algebra Appl. 345 (2002), 225–233.
MR 1883274 |
Zbl 0995.15006
[10] H. J. S. Smith: On the value of a certain arithmetical determinant. Proc. London Math. Soc. 7 (1875–1876), 208–212.