UFD
An integral domain D satisfying
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Every nonzero element of D that is not a unit can be factored into a product of a finite number of irreducibles
,
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If p1p2⋯pr and q1q2⋯qs are two factorizations of the same element a into irreducibles, then r=s and we can reorder the qj’s in a way that qj is an associate
element of pj for all j
is called a unique factorization domain (UFD), also a factorial ring.
The factors p1,p2,…,pr are called the prime factors of a.
Some of the classic results about UFDs:
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On a UFD, the concept of prime element
and irreducible element coincide.
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If F is a field, then F[x] is a UFD.
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If D is a UFD, then D[x] (the ring of polynomials on the variable x over D) is also a UFD.
Since R[x,y]≅R[x][y], these results can be extended to rings of polynomials with a finite number of variables.
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If D is a principal ideal domain
, then it is also a UFD.
The converse is, however, not true. Let F a field and consider the UFD F[x,y]. Let I the ideal consisting of all the elements of F[x,y] whose constant term is 0. Then it can be proved that I is not a principal ideal
. Therefore not every UFD is a PID.
Title | UFD |
Canonical name | UFD |
Date of creation | 2013-03-22 11:56:22 |
Last modified on | 2013-03-22 11:56:22 |
Owner | drini (3) |
Last modified by | drini (3) |
Numerical id | 19 |
Author | drini (3) |
Entry type | Definition |
Classification | msc 13G05 |
Synonym | unique factorization domain |
Related topic | IntegralDomain |
Related topic | Irreducible |
Related topic | EuclideanRing |
Related topic | EuclideanValuation |
Related topic | ProofThatAnEuclideanDomainIsAPID |
Related topic | WhyEuclideanDomains |
Related topic | Y2X32 |
Related topic | PID |
Related topic | PIDsAreUFDs |
Related topic | FundamentalTheoremOfArithmetic |
Defines | factorial ring |
Defines | prime factor |
Defines | UFD |
Defines | unique factorization |