Article
Keywords:
generalized ciculant Boolean matrix; sandwich semigroup; idempotent element; maximal subgroup
Summary:
Let $n$  be a positive integer, and $C_{n} (r)$ the set of all $n\times n$ $r$-circulant matrices over the Boolean algebra $B=\lbrace 0,1\rbrace $, $G_{n}=\bigcup _{r=0}^{n-1}C_{n}(r)$. For any fixed $r$-circulant matrix  $C$ ($C\ne 0$) in  $G_{n}$, we define an operation “$\ast $” in  $G_{n}$ as follows: $A\ast B=ACB$ for any $A,B$ in  $G_{n}$, where $ACB$  is the usual product of Boolean matrices. Then $(G_{n},\ast )$  is a semigroup. We denote this semigroup by  $G_{n}(C)$ and call it the sandwich semigroup of generalized circulant Boolean matrices with sandwich matrix  $C$. Let $F$  be an idempotent element in  $G_{n}(C)$ and $M(F)$ the maximal subgroup in  $G_{n}(C)$ containing the idempotent element $F$. In this paper, the elements in $M(F)$ are characterized and an algorithm to determine all the elements in $M(F)$ is given.
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