Dense subgroups in the group of interval exchange transformations

The paper concerns the characterization of the group $\mathop{IET}$ of interval exchange transformations (iet). We investigate a class of rational subgroups of $\mathop{IET}$. These are subgroups consisting of iet transformations defined by partitions with rational endpoints. We propose a characterization of rational subgroups in terms of infinite supernatural numbers and prove that every such subgroup is dense in $\mathop{IET}$. We also discuss the properties of these groups.