A + bω

Definition

The expression 'a + bω' represents a type of number known as an Eisenstein integer, where 'a' and 'b' are integers, and 'ω' is a primitive cube root of unity, specifically defined as $$rac{-1 + i\sqrt{3}}{2}$$. This form connects to the broader context of algebraic integers and number theory, illustrating how complex numbers can be represented in a structured way, especially in systems where cubic roots play a key role.

5 Must Know Facts For Your Next Test

1. 'ω' satisfies the equation $$ω^3 = 1$$, demonstrating its unique properties among complex numbers.
2. Eisenstein integers form a lattice in the complex plane, allowing for geometric interpretations of their structure.
3. The norm of an Eisenstein integer 'a + bω' is given by the formula $$N(a + bω) = a^2 - ab + b^2$$, which helps in understanding divisibility within this system.
4. Eisenstein integers are integral over the integers, meaning they satisfy monic polynomials with integer coefficients.
5. The ring of Eisenstein integers is a unique factorization domain (UFD), which means every non-zero element can be factored uniquely into irreducible elements, up to ordering and units.

Review Questions

• How do Eisenstein integers relate to other types of integers in algebraic number theory?
  • Eisenstein integers expand the concept of integers into the complex plane, similar to how Gaussian integers introduce complex numbers with integer coefficients. Both types of numbers allow for unique factorizations and help illustrate the properties of rings in algebraic number theory. By understanding Eisenstein integers, one can better appreciate the diversity within algebraic structures and their applications.
• Discuss the significance of the norm function for Eisenstein integers and how it contributes to understanding their divisibility.
  • The norm function for Eisenstein integers, given by $$N(a + bω) = a^2 - ab + b^2$$, is crucial for analyzing divisibility within this set. It provides a way to measure sizes and relationships between elements in the ring, similar to how norms work in other number systems. Understanding how norms interact helps in establishing properties like unique factorization and can aid in solving problems related to integer representations.
• Evaluate the implications of Eisenstein integers being a unique factorization domain (UFD) on their arithmetic properties.
  • Being a unique factorization domain means that every non-zero Eisenstein integer can be factored uniquely into irreducible elements up to units and ordering. This property simplifies many arithmetic operations and allows for clearer insights into solutions of polynomial equations involving Eisenstein integers. It also lays foundational principles for higher-dimensional algebraic structures, influencing areas such as algebraic geometry and number theory.

Related terms

Eisenstein Integers: These are complex numbers of the form 'a + bω', where 'a' and 'b' are integers and 'ω = \frac{-1 + i\sqrt{3}}{2}'.

Gaussian Integers: These are complex numbers of the form 'm + ni', where 'm' and 'n' are integers, serving as a foundational concept in number theory similar to Eisenstein integers.

Ring of Integers: This refers to the set of algebraic integers in a number field, which includes Eisenstein integers and is integral to the study of algebraic structures.