Landau prime ideal theorem
{{short description|Provides an asymptotic formula for counting the number of prime ideals of a number field}}
In algebraic number theory, the prime ideal theorem is the number field generalization of the prime number theorem. It provides an asymptotic formula for counting the number of prime ideals of a number field K, with norm at most X.
Example
What to expect can be seen already for the Gaussian integers. There for any prime number p of the form 4n + 1, p factors as a product of two Gaussian primes of norm p. Primes of the form 4n + 3 remain prime, giving a Gaussian prime of norm p2. Therefore, we should estimate
:
where r counts primes in the arithmetic progression 4n + 1, and r′ in the arithmetic progression 4n + 3. By the quantitative form of Dirichlet's theorem on primes, each of r(Y) and r′(Y) is asymptotically
:
Therefore, the 2r(X) term dominates, and is asymptotically
:
General number fields
This general pattern holds for number fields in general, so that the prime ideal theorem is dominated by the ideals of norm a prime number. As Edmund Landau proved in {{harvnb|Landau|1903}}, for norm at most X the same asymptotic formula
:
always holds. Heuristically this is because the logarithmic derivative of the Dedekind zeta-function of K always has a simple pole with residue −1 at s = 1.
As with the Prime Number Theorem, a more precise estimate may be given in terms of the logarithmic integral function. The number of prime ideals of norm ≤ X is
:
where cK is a constant depending on K.
See also
References
- {{cite book | author=Alina Carmen Cojocaru|author1-link= Alina Carmen Cojocaru |author2=M. Ram Murty | title=An introduction to sieve methods and their applications | series=London Mathematical Society Student Texts |date= 8 December 2005 | volume=66 | publisher=Cambridge University Press | isbn=0-521-61275-6 | pages=35–38 |author2-link= M. Ram Murty }}
- {{Cite journal
| doi=10.1007/BF01444310
| last=Landau
| first=Edmund
| author-link=Edmund Landau
| title=Neuer Beweis des Primzahlsatzes und Beweis des Primidealsatzes
| year=1903
| journal=Mathematische Annalen
| volume=56
| issue=4
| pages=645–670
| s2cid=119669682
| url=https://zenodo.org/record/1735140
}}
- {{cite book | author=Hugh L. Montgomery | authorlink=Hugh Montgomery (mathematician) |author2=Robert C. Vaughan |authorlink2=Robert Charles Vaughan (mathematician) | title=Multiplicative number theory I. Classical theory | series=Cambridge tracts in advanced mathematics | volume=97 | year=2007 | isbn=978-0-521-84903-6 | pages=266–268}}