**Thesis Type:** Doctorate

**Institution Of The Thesis:** Uludağ Üniversitesi, Turkey

**Approval Date:** 2006

**Thesis Language:** Turkish

**Student:** GÖKHAN SOYDAN

**Supervisor: **İSMAİL NACİ CANGÜL

In this thesis, the number of rational points, their orders, and the group structure of them, on Bachet elliptic curves y2 = x3 + a3 which are the special case of simplified Weierstrass equation over finite fields F where is prime, are studied. p p In the first chapter, the fundamental notions necessary in the second and third chapters are recalled. In the second chapter, some results concerning the number of rational points on Bachet elliptic curves y2 = x3 + a3 are given. In the third chapter, it is shown that the group structure of the rational points on these curves is cyclic when p a 5 (mod 6) is prime; and while p a 1 (mod 6) is prime, it is isomorphic to the direct product of two cyclic groups Cn ×Cnm where m,n ý+ or to the direct product Cn ×Cn with p = n2 ± n +1. While studying the group structure of these curves, the number of points is also discussed. Furthermore, whether the group has a point of order three or not according to a belongs to or not is shown.