cyclotomic fields

E157383

Cyclotomic fields are number fields obtained by adjoining complex roots of unity to the rationals, playing a central role in algebraic number theory and classical geometric constructibility.

All labels observed (1)

Label Occurrences
cyclotomic fields canonical 1

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Statements (51)

Predicate Object
instanceOf algebraic number field
mathematical object
number field
appliedIn construction problems in classical geometry
study of Fermat’s Last Theorem (classical approach)
study of regular and irregular primes
baseField rational numbers
centralTo Iwasawa theory
Kummer theory
class field theory over Q
theory of cyclotomic integers
characterizedBy every finite abelian extension of Q is contained in a cyclotomic field
regular n-gon is constructible with straightedge and compass iff Q(ζ_n) has degree a power of 2
constructedBy adjoining a primitive n-th root of unity ζ_n to Q
contains n-th roots of unity
definedAs a number field obtained by adjoining a primitive root of unity to the rational numbers
degreeOverQ φ(n)
fieldOfStudy algebraic number theory
number theory
generatedAsQAlgebraBy root of Φ_n(x)
generatedBy primitive n-th root of unity
hasAssociatedLFunction Dirichlet L-functions attached to characters of (Z/nZ)×
hasAssociatedPolynomial n-th cyclotomic polynomial Φ_n(x)
hasClassGroup ideal class group depending on n
hasDiscriminant explicit formula in terms of n and its prime factors
hasEmbedding embeds into C via complex embeddings
hasGaloisGroup multiplicative group of units modulo n
hasGaloisGroupIsomorphicTo (Z/nZ)×
hasInvariant Euler totient φ(n) as its degree over Q
hasMinimalPolynomialOverQ Φ_n(x)
hasPrimeDecomposition rational primes factor according to congruence conditions modulo n
hasProperty abelian extension of Q
class number may exceed 1
finite extension of Q
normal extension of Q
separable extension of Q
totally imaginary for n>2
hasRamifiedPrimes primes dividing n
hasRingOfIntegers Z[ζ_n] for n>2
hasSubfield maximal real subfield Q(ζ_n+ζ_n^{-1})
totally real maximal real subfield
hasUnitGroup Dirichlet unit group of rank φ(n)/2−1 for n>2
hasUnramifiedPrimes primes not dividing n
isGaloisExtensionOf Q
relatedTo Kronecker–Weber theorem
constructible regular polygons
studiedBy Ernst Eduard Kummer
surface form: Ernst Kummer

Leopold Kronecker
Richard Dedekind
symbolicallyDenotedAs Q(ζ_n)
usedInProofOf Kronecker–Weber theorem

How these facts were elicited

Referenced by (1)

Full triples — surface form annotated when it differs from this entity's canonical label.