S
-integers and S
-units of fraction fields of Dedekind domains #
Let K
be the field of fractions of a Dedekind domain R
, and let S
be a set of prime ideals in
the height one spectrum of R
. An S
-integer of K
is defined to have v
-adic valuation at most
one for all primes ideals v
away from S
, whereas an S
-unit of Kˣ
is defined to have v
-adic
valuation exactly one for all prime ideals v
away from S
.
This file defines the subalgebra of S
-integers of K
and the subgroup of S
-units of Kˣ
, where
K
can be specialised to the case of a number field or a function field separately.
Main definitions #
Set.integer
:S
-integers.Set.unit
:S
-units.- TODO: localised notation for
S
-integers.
Main statements #
Set.unitEquivUnitsInteger
:S
-units are units ofS
-integers.IsDedekindDomain.integer_empty
:∅
-integers is the usual ring of integers.- TODO: proof that
S
-units is the kernel of a map to a product. - TODO: finite generation of
S
-units and Dirichlet'sS
-unit theorem.
References #
- D Marcus, Number Fields
- J W S Cassels, A Fröhlich, Algebraic Number Theory
- J Neukirch, Algebraic Number Theory
Tags #
S integer, S-integer, S unit, S-unit
S
-integers #
The R
-subalgebra of S
-integers of K
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
If S
is the whole set of places of K
, then the S
-integers are the whole of K
.
If S
is the empty set, then the S
-integers are the minimal R
-subalgebra of K
(which is
just R
itself, via Algebra.botEquivOfInjective
and IsFractionRing.injective
).
S
-units #
The subgroup of S
-units of Kˣ
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The group of S
-units is the group of units of the ring of S
-integers.
Equations
- One or more equations did not get rendered due to their size.