geografia: Prime number

Evidence: 100 • authority: 72

A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a product (2 × 2) in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order. The property of being prime is called primality. A simple but slow meth…

Evidence: 82 • authority: 72

In mathematics, the fundamental theorem of arithmetic, also called the unique factorization theorem and prime factorization theorem, states that every integer greater than 1 is either prime or can be represented uniquely as a product of prime numbers, up to the order of the factors. For example, 1200 = 2 4 ⋅ 3 1 ⋅ 5 2 = ( 2 ⋅ 2 ⋅ 2 ⋅ 2 ) ⋅ 3 ⋅ ( 5 ⋅ 5 ) = 5 ⋅ 2 ⋅ 5 ⋅ 2 ⋅ 3 ⋅ 2 ⋅ 2 = … {\displaystyle 1200=2^{4}\cdot 3^{1}\cdot 5^{2}=(2\cdot 2\cdot 2\cdot 2)\cdot 3\cdot (5\cdot 5)=5\cdot 2\cdot 5\cdot 2\cdot 3\cdot 2\cdot 2=\ldots } The theorem says two things about this example: first, that 1200 can be represented as a product of primes, and second, that no matter how this is done, there wil…

Evidence: 76 • authority: 72

In mathematics, integer factorization is the decomposition of a positive integer into a product of integers. Every positive integer greater than 1 is either the product of two or more integer factors greater than 1, in which case it is a composite number, or it is not, in which case it is a prime number. For example, 15 is a composite number because 15 = 3 · 5, but 7 is a prime number because it cannot be decomposed in this way. If one of the factors is composite, it can in turn be written as a product of smaller factors, for example 60 = 3 · 20 = 3 · (5 · 4). Continuing this process until every factor is prime is called prime factorization; the result is always unique up to the order of th…

Evidence: 73 • authority: 72

In mathematics, factorization (or factorisation, see English spelling differences) or factoring consists of writing a number or another mathematical object as a product of several factors, usually smaller or simpler objects of the same kind. For example, 3 × 5 is an integer factorization of 15, and (x − 2)(x + 2) is a polynomial factorization of x2 − 4. Factorization is not usually considered meaningful within number systems possessing division, such as the real or complex numbers, since any x {\displaystyle x} can be trivially written as ( x y ) × ( 1 / y ) {\displaystyle (xy)\times (1/y)} whenever y {\displaystyle y} is not zero. However, a meaningful factorization for a rational number o…

Evidence: 52 • authority: 72

In number theory, Dirichlet's theorem, also called the Dirichlet prime number theorem, states that for any two positive coprime integers a and d, there are infinitely many primes of the form a + nd, where n is also a positive integer. In other words, there are infinitely many primes that are congruent to a modulo d. The numbers of the form a + nd form an arithmetic progression a , a + d , a + 2 d , a + 3 d , … , {\displaystyle a,\ a+d,\ a+2d,\ a+3d,\ \dots ,\ } and Dirichlet's theorem states that this sequence contains infinitely many prime numbers. The theorem extends Euclid's theorem that there are infinitely many prime numbers (of the form 1 + 2n). Stronger forms of Dirichlet's theorem s…

Evidence: 40 • authority: 72

In mathematics, a unique factorization domain (UFD) (also sometimes called a factorial ring following the terminology of Bourbaki) is a ring in which a statement analogous to the fundamental theorem of arithmetic holds. Specifically, a UFD is an integral domain (a nontrivial commutative ring in which the product of any two non-zero elements is non-zero) in which every non-zero non-unit element can be written as a product of irreducible elements, uniquely up to order and units. Important examples of UFDs are the integers and polynomial rings in one or more variables with coefficients coming from the integers or from a field. Unique factorization domains appear in the following chain of class…

Evidence: 29 • authority: 72

The fundamental theorem of algebra, also called d'Alembert's theorem or the d'Alembert–Gauss theorem, states that every non-constant single-variable polynomial with complex coefficients has at least one complex root. This includes polynomials with real coefficients, since every real number is a complex number with its imaginary part equal to zero. Equivalently (by definition), the theorem states that the field of complex numbers is algebraically closed. The theorem is also stated as follows: every non-zero, single-variable, degree n polynomial with complex coefficients has, counted with multiplicity, exactly n complex roots. The equivalence of the two statements can be proven through the us…

Evidence: 29 • authority: 72

Euclid's theorem is a fundamental statement in number theory that asserts that there are infinitely many prime numbers. It was first proven by Euclid in his work Elements. There are at least 200 proofs of the theorem.

Evidence: 23 • authority: 88

Unique factorization of pseudo-arithmetic functions. In 1959, Cashwell and Everett proved that the set of complex-valued arithmetic functions forms a unique factorization domain under addition and convolution. In this thesis we further this result in two directions. In the first direction, we replace the set of all natural numbers and the complex field by an arithmetical semigroup S and a unique factorization domain D, respectively, and prove that when the ring of formal power series in any finite number of indeterminates over D is a unique factorization domain, then the set of all pseudo-arithmetic functions from S into D is a unique factorization domain under addition and convolution. In…

Evidence: 23 • authority: 80

Unique factorization and the fundamental theorem of arithmetic

Evidence: 23 • authority: 80

On the Fundamental Theorem in Arithmetic Progression of Primes