Let Ω be a finite set and T(Ω) the full transformation monoid on Ω. The rank of t∈T(Ω) is natural number |Ωt|. Given A⊆T(Ω), denote by 〈A〉 semigroup generated A. k fixed such that 2≤k≤|Ω|. In first part this paper we (almost) classify permutation groups G for all transformations t∈T(Ω), every element in St:=〈G,t〉 can written as product eg, where e2=e∈St g∈G. second prove, among other results, i...

In this paper, we construct some directed strongly regular Cayley graphs on Dihedral groups, which generalizes earlier constructions. We also characterize certain groups Dpα, where p is a prime and α ≥ 1 positive integer.