A Lecturer in the Department of Mathematics (Asst. Prof. Dr. Riyad Delfi Ali) received a letter of thanks and appreciation from the President of Tikrit University, Prof. Dr. (Waad Mahmoud Raouf), in appreciation of his efforts in the membership of the doctoral thesis discussion committee for the student (Nabila Ibrahim Aziz) From the Department of Mathematics in the College of Computer Science and Mathematics / University of Tikrit at the University of Tikrit, which had an effective impact on our dear university and our beloved Iraq.