Dedekind zeta fonksiyonu ve analitik sınıf sayısı formülü

In this thesis, we first introduce number fields and their rings of integers. We show that the ring of integers of a number field is an integrally closed, Noetherian ring such that its prime and maximal ideals coincide. Namely, it is a Dedekind domain. To study the ring of integers of a number field in details, we present a geometric approach so that the number field is embedded inside a finite dimensional real vector space. By doing so, we show that the class number of the number field is finite. In addition, we characterize the group of units of $\mathcal{O}_K$ via geometric methods. After that, we define the Dedekind zeta function of a number field. It is a generalization of the Riemann zeta function. Moreover, we present the Analytic Class Number Formula, which states that the Dedekind zeta function converges for any complex number with real part greater than 1 and has a simple pole at the point 1. Its residue at the point 1 is given by invariants of the number field. Lastly, we present various arguments to evaluate the class number of various number fields.