After publication of article [1], we became aware of the fact that sections of this article were taken verbatim without quotation from [2] and [3] listed below. In addition, ‘example 2’ and ‘algorithm 4.1’ as presented in this article are identical to ‘example 3.3’ from [3] and ‘algorithm 4.1’ from [2]. In light of these problems and in consultation with the journal's Section Editor for Mathematics we have decided to retract this article from SpringerPlus.