See Also: integral domain, irreducible, Euclidean domain, Euclidean valuation, proof that a Euclidean domain is a PID, motivation for Euclidean domains,
This is version 12 of UFD, born on 2001-11-04, modified 2006-12-22.
In mathematics, a uniquefactorizationdomain (UFD) is, roughly speaking, a ring in which every element can be uniquely written as a product of prime elements, analogous to the fundamental theorem of arithmetic for the integers.
The uniqueness part is sometimes hard to verify, which is why the following equivalent definition is useful: a uniquefactorizationdomain is an integral domain R in which every non-zero non-unit can be written as a product of prime elements of R.
The most important examples of Dedekind domains, and historically the motivating ones, arise from algebraic number fields: start with a finite field extension F of the rational numbers Q and consider the set of all elements of F which are algebraic integers (in other words, the integral closure of Z in F).
The ideal class group measures the failure of uniquefactorization in a Dedekind domain (by measuring the failure of ideals to be principal).
The study of Dedekind domains began when Richard Dedekind introduced the notion of ideal in a ring in the hopes of compensating for the failure of uniquefactorization into primes in rings of algebraic integers.
In mathematics, a uniquefactorizationdomain (UFD) is, roughly speaking, a commutative ring in which every element can be uniquely written as a product of prime elements, analogous to the fundamental theorem of arithmetic for the integers.
A Noetherian integral domain is a UFD if and only if every height 1 prime ideal is principal.
An integral domain is a UFD if and only if the ascending chain condition holds for principal ideals, and any two elements of A have a least common multiple.
In a broad sense, 0 can be factorized, as 0*1, 0*2, 0*3, 0*5, etc. But none of these are primefactorizations, because 0 is not a prime but is involved.
The uniqueness is proved by appealing to the characterizing theorem of primes.
Or, appeal to results in abstract algebra - the set of integers is a Euclidean domain, and therefore a principle ideal domain, and therefore a uniquefactorizationdomain.
Uniquefactorization of integers into primes is a fundamental result, and one which goes back to Euclid.
Definition An integral domain R is a uniquefactorizationdomain (UFD) if the conclusion of the Fundamental Theorem of Arithmetic holds for R, i.e., if every non-zero element of R has an essentially uniquefactorization into irreducibles.
It is a general theorem that in a UFD, primes and irreducibles are the same, while in a non-UFD, every prime is an irreducible, but an irreducible need not be prime.
Let D be a principal ideal domain, and let p be a nonzero element of D. Then p is irreducible in D if and only if pD is a prime ideal of D. Definition.
Any principal ideal domain is a uniquefactorizationdomain.
Let D be a uniquefactorizationdomain, let Q be the quotient field of D, and let f(x) be a primitive polynomial in D[x].
And, as a consequence, the primefactorization is unique in Z[i].
In 1847, G.Lamé (1795-1870) gave a talk at a meeting of the French Academy where he announced a solution to Fermat's Theorem and suggested that the glory of solving the famous theorem should be shared with J.Liouville (1809-1882) to whom he ascribed the method of solution.
Lamé left his mark in the Theory of Elasticity and Mathematical Physics, he introduced curvilinear coordinates, and in his honor were named an equation, a set of coefficients, and a special class of functions.
Among the new additions are a chapter on uniquefactorization, a number theory thread which runs throughout several optional sections, and an overview of techniques of computing Galois groups.
In Chapter 3 the abstract definition of a group is introduced, and the students encounter the notion of a group armed with a variety of concrete examples.
When factor groups are introduced in Chapter 3, we have partitions and equivalence relations at our disposal, and we are able to concentrate on the group structure introduced on the equivalence classes.
In comparison to steganography, however, cryptography does not involve hiding the information itself, but changing it so that it is rendered incomprehensible to all but the intended parties.
The is important in cryptography because quantum computers can factor large numbers very, very easily.
In other words, there's one unique way to factor every number into the primes that compose it.