The distinguishing number of groups based on the distinguishing number of subgroups

Saeid Alikhani, Samaneh Soltani

Published 2016-12-31Version 1

Let $\Gamma$ be a group acting on a set $X$. The distinguishing number for this action of $\Gamma$ on $X$, denoted by $D_{\Gamma}(X)$, is the smallest natural number $k$ such that the elements of $X$ can be labeled with $k$ labels so that any label-preserving element of $\Gamma$ fixes all $x \in X$. In particular, if the action is faithful, then the only element of $\Gamma$ preserving labels is the identity. In this paper, we obtain an upper bound on the distinguishing number of a set knowing the distinguishing number of a set under the action of a subgroup. By the concept of motion, we obtain an upper bound for the distinguishing number of a group. Motivated by a problem (Chan 2006), we characterize $D_{\Gamma,H}(X)$ which is the smallest number of labels admitting a labeling of $X$ such that the only elements of $\Gamma$ that induce label-preserving permutations lie in $H$. Finally, we state two algorithms for obtaining an upper and a lower bound for $D_{\Gamma , H}(X)$.