TAILIEUCHUNG - Arithmetic in Extensions of Q

What makes work with rational numbers and integers comfortable are the essential properties they have, especially the unique factorization property (the Main Theorem of Arithmetic). However, the might of the arithmetic in Q is bounded. Thus, some polynomials, although they have zeros, cannot be factorized into polynomials with rational coefficients. | The IMO Compendium jroup 2007 The Author s and The IMO Compendium Group Ofympiaif Iraininff Materials compendium com Arithmetic in Extensions of Q Dusan DjukiC Contents 1 General Properties . 1 2 Arithmetic in the Gaussian Integers Z i . 4 3 Arithmetic in the ring Z w . 5 4 Arithmetic in other quadratic rings. 6 1 General Properties What makes work with rational numbers and integers comfortable are the essential properties they have especially the unique factorization property the Main Theorem of Arithmetic . However the might of the arithmetic in Q is bounded. Thus some polynomials although they have zeros cannot be factorized into polynomials with rational coefficients. Nevertheless such polynomials can always be factorized in a wider field. For instance the polynomial x2 1 is irreducible over Z or Q but over the ring of the so called Gaussian integers Z i a bi a b G Z it can be factorized as x i x - i . Sometimes the wider field retains many properties of the rational numbers. In particular it will turn out that the Gaussian integers are a unique factorization domain just like the rational integers Z. We shall first discuss some basics of higher algebra. Definition 1. A number a G C is algebraic if there is a polynomial p x anxn an-1xn-1 a0 with integer coefficients such that p a 0. If an 1 then a is an algebraic integer. Further p x is the minimal polynomial of a if it is irreducible over Z x . it cannot be written as a product of nonconstant polynomials with integer coefficients . Example 1. The number i is an algebraic integer as it is a root of the polynomial x2 1 which is also its minimal polynomial. Number y 2 yC is also an algebraic integer with the minimal polynomial x4 10x2 1 verify . Example 2. The minimal polynomial of a rational number q a b a G Z b G N a b 1 is bx a. By the definition q is an algebraic integer if and only if b 1 . if and only if q is an integer. Definition 2. Let a be an algebraic integer andp x xn .

TÀI LIỆU LIÊN QUAN
TỪ KHÓA LIÊN QUAN
TAILIEUCHUNG - Chia sẻ tài liệu không giới hạn
Địa chỉ : 444 Hoang Hoa Tham, Hanoi, Viet Nam
Website : tailieuchung.com
Email : tailieuchung20@gmail.com
Tailieuchung.com là thư viện tài liệu trực tuyến, nơi chia sẽ trao đổi hàng triệu tài liệu như luận văn đồ án, sách, giáo trình, đề thi.
Chúng tôi không chịu trách nhiệm liên quan đến các vấn đề bản quyền nội dung tài liệu được thành viên tự nguyện đăng tải lên, nếu phát hiện thấy tài liệu xấu hoặc tài liệu có bản quyền xin hãy email cho chúng tôi.
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.