1. Department of Mathematics, National University of Modern Languages, Islamabad, Pakistan
2. Department of Mathematics and Statistics, Riphah International University I-14, Islamabad 44 000, Pakistan
3. Quantum Leap Africa (QLA), AIMS Rwanda Centre, Remera Sector KN 3, Kigali, Rwanda
4. Institut de Mathématiques et de Sciences Physiques (IMSP/UAC), Laboratoire de Topologie Fondamentale, Computationnelle et Leurs Applications (Lab-ToFoCApp), BP 613 Porto-Novo, Benin
5. African Center for Advanced Studies, P.O. Box 4477, Yaounde, Cameroon