Polynomial over the final field called the formal sum of the form
Here Is a non-negative integer called the degree of the polynomial , but Are elements of algebra over the multiplication of which is specified by the rules:
Such a definition allows us to formally multiply polynomials without worrying about the fact that different degrees of the same element of a finite field can coincide [1] [2] .
Any function over a finite field can be defined using some polynomial (for example, the Lagrange interpolation polynomial ).
Content
- 1 Related Definitions
- 2 Roots of a polynomial
- 3 Cyclotomy class
- 3.1 Examples of cyclotomic classes
- 3.2 Relations with the roots of polynomials
- 4 Types of polynomials
- 4.1 Primitive polynomials
- 4.2 Circular polynomials
- 4.3 Zhegalkin polynomials
- 5 Application
- 6 See also
- 7 notes
- 8 Literature
Related Definitions
- Number
called the degree of the polynomial and is denoted as
[2] .
- If
, then the polynomial is called normalized (reduced) [2] . A polynomial can always be normalized by dividing it by a coefficient
with an older degree.
- The sum and product of polynomials are defined in the usual way, and operations with coefficients are carried out in the field
.
- For two polynomials
and
there are always polynomials
and
over the field
that the relation will be satisfied
- If the degree
strictly less degree
, then this relation is called the polynomial representation
in the form of quotient and remainder of division
on
, and such a representation is unique [3] . It's clear that
divided without remainder into
that is written as
[4] .
- If
then the polynomial
called a polynomial divisor
[5] .
-
- A polynomial is irreducible over a field
if it has no non-trivial divisors (degrees greater than 0 and less
) [5] [6] .
- Field extension
called set
residue classes modulo an irreducible polynomial
over the field
[6] .
- Minimum polynomial (minimum function) for an element
from the extended field such a normalized polynomial is called
over
minimum degree that
[7] [8] .
- The root of a polynomial is any element of a field whose value of this polynomial is equal to zero.
- Conjugate elements of a field that are the roots of the same irreducible polynomial are called conjugate [9] .
Polynomial Roots
A polynomial of degree m has exactly m roots (taking into account multiplicity) belonging to some extended field . If where - simple then . Based on the properties of the finite fields, any element of the field is the root of the binomial :
So the roots of the polynomial are also the roots of the binomial [10] .
The Bezout theorem and its corollaries are valid:
Remainder of the division on is equal to . |
If - root then divides . |
If the essence of the roots then |
The following theorems are also valid:
Theorem 1 If - root then - also root [11] . |
Theorem 2 The conjugate elements of the Galois field are of the same order [9] . |
Cyclotomy class
A consequence of Theorem 1 may be the fact that if - polynomial root over the field then are its roots.
Definition: cyclotomic class over a field generated by some element called the set of all the different elements which are degrees [12] .
If Is a primitive element [13] (such an element that and at ) fields then the cyclotomic class over the field will have exactly elements.
It should be noted that any element of the cyclotomic class can generate this and only this class, and, therefore, belong only to it.
Examples of cyclotomic classes
Example 1. Let , and - primitive field element , i.e and at . Considering also that , we can obtain the expansion of all nonzero elements of the field into three cyclotomic classes over the field :
Example 2. Similarly, we can construct classes on the field over the field , i.e . Let be - primitive field element means .
Connection with the roots of polynomials
The following theorem establishes a connection between cyclotomic classes and the expansion of a polynomial to irreducible polynomials over a field .
Theorem 3. Let element cyclotomic class and polynomial has as its roots the elements of this cyclotomic class, i.e. Then the coefficients polynomial lie in the field , and the polynomial itself is irreducible over this field. |
One can establish the following corollary from Theorem 3 . From the property of finite fields, which says that all nonzero elements of the field are the roots of the polynomial , we can conclude that the polynomial can be decomposed into irreducible over the field polynomials , each of which corresponds to its cyclotomic class [14] .
Types of Polynomials
Primitive polynomials
Definition The root order of the irreducible polynomial is called the exponent to which this polynomial belongs. An irreducible polynomial is called primitive if all its roots are generating elements of the multiplicative group of the field [15] . |
All roots of a primitive polynomial have an order equal to the order of the multiplicative group of the extended field , i.e [11] .
Circular Polynomials
Let be is the generating element of the multiplicative group of the field , and its order is , i.e . Let all the elements of order are the roots of the polynomial . Then such a polynomial is called circular and equality is true [16] :
Zhegalkin polynomials
Among the polynomials over finite fields, Zhegalkin polynomials are especially distinguished. They are polynomials of many variables over a field [17] .
With the help of such a polynomial, any Boolean function can be specified [18] , and uniquely [17] [19] .
Application
There are many algorithms that use polynomials over finite fields and rings.
- Euclidean Algorithm
- Burlekamp Algorithm
- Burlekamp Algorithm - Massey
- Burlekamp Method
- Bowes Code - Chowdhury - Hockingham
- Reed - Solomon Code
- CRC
- Agrawala Test - Kayala - Saxen
- Shamir's secret sharing scheme
Also, polynomials over finite fields are used in modern noise-resistant coding [20] (for describing cyclic codes [21] and for decoding the Reed – Solomon code using the Euclidean algorithm [22] ), pseudorandom number generators [23] (implemented using shift registers ) [24] , stream encryption [25] and data integrity verification algorithms.
See also
- Polynomial
- Final field
- Polynomial ring
Notes
- ↑ Akritas, 1994 , p. 146.
- ↑ 1 2 3 Bleikhut, 1986 , p. 88.
- ↑ Bleichut, 1986 , p. 90.
- ↑ Bleichut, 1986 , p. 91.
- ↑ 1 2 Bleikhut, 1986 , p. 89.
- ↑ 1 2 Sagalovich, 2014 , p. 79.
- ↑ Sagalovich, 2014 , p. 93.
- ↑ Bleichut, 1986 , p. 104.
- ↑ 1 2 Sagalovich, 2014 , p. 101.
- ↑ Sagalovich, 2014 , p. 82.
- ↑ 1 2 Sagalovich, 2014 , p. 96.
- ↑ Sagalovich, 2014 , p. 105.
- ↑ Bleichut, 1986 , p. 99.
- ↑ Sagalovich, 2014 , p. 97.
- ↑ Bleichut, 1986 , p. 103.
- ↑ Sagalovich, 2014 , p. 102.
- ↑ 1 2 Yablonsky, 1986 , p. 32.
- ↑ Yablonsky, 1986 , p. 12.
- ↑ Gabidulin, Kshevetsky, Kolybelnikov, 2011 , p. 81.
- ↑ Sagalovich, 2014 , p. 169-172.
- ↑ Bleichut, 1986 , p. 116-121.
- ↑ Bleichut, 1986 , p. 223-228.
- ↑ Gabidulin, Kshevetsky, Kolybelnikov, 2011 , p. 77-83.
- ↑ Alferov, Teeth, Kuzmin et al., 2005 , p. 251-260.
- ↑ Gabidulin, Kshevetsky, Kolybelnikov, 2011 , p. 74-83.
Literature
- Akritas A. Fundamentals of computer algebra with applications / trans. from English E.V. Pankratieva . - M .: Mir, 1994 .-- 544 p.
- Alferov A. P. , Zubov A. Yu. , Kuzmin A. S. et al. Fundamentals of cryptography : Textbook - 3rd ed., Rev. and add. - M .: Helios ARV , 2005 .-- 480 p. - ISBN 978-5-85438-137-6
- Bleikhut R. E. Theory and Practice of Error Control Codes / Ed. K. Sh. Zigangirova - M .: Mir , 1986 .-- 576 p.
- Gabidulin E.M. , Kshevetsky A.S. , Kolybelnikov A.I. Information security : a training manual - M .: MIPT , 2011. - 225 p. - ISBN 978-5-7417-0377-9
- Sagalovich Yu. L. Introduction to algebraic codes - 3rd ed., Rev. and add. - M .: IPPI RAS , 2014 .-- 310 p. - ISBN 978-5-901158-24-1
- Yablonsky S. V. Introduction to discrete mathematics : Textbook. manual for universities - 2nd ed., revised. and add. - M .: Nauka , 1986 .-- 384 p.
- Peterson W., Weldon E. Error Correcting Codes. - M .: Mir, 1976 .-- S. 596.