Definition of a Ring without Unit

Oct 13, 2025 by wbrum.org 95 views

Introduction

In abstract algebra, a ring is a mathematical structure that consists of a set together with two binary operations, usually called addition and multiplication. A polynomial ring is a specific type of ring that consists of polynomials with coefficients from a given ring. In this article, we will discuss zero divisors in polynomials ring without unit, without using polynomial notation.

Definition of a Ring without Unit

A ring without unit is a ring that does not have a multiplicative identity element. In other words, there is no element in the ring that, when multiplied by any other element, results in that same element. This is in contrast to a ring with unit, which does have a multiplicative identity element.

Definition of a Polynomials Ring

A polynomials ring, denoted by $P(I,A)$ , is a ring of functions $f:^{\,(I)}\mathbb{N}\to A$ with finite support. Here, $I$ is a set and $A$ is a ring without unit. The functions in $P(I,A)$ are called polynomials, and they are defined as follows:

A polynomial $f$ is a function from the set of natural numbers $\mathbb{N}$ to the ring $A$ .
The support of a polynomial $f$ is the set of natural numbers $n$ such that $f(n) \neq 0$ .
A polynomial $f$ has finite support if the support of $f$ is a finite set.

Definition of Zero Divisors

A zero divisor in a ring is an element that, when multiplied by another non-zero element, results in zero. In other words, an element $a$ is a zero divisor if there exists a non-zero element $b$ such that $ab = 0$ .

Zero Divisors in Polynomials Ring

In a polynomials ring $P(I,A)$ , a zero divisor is an element that, when multiplied by another non-zero element, results in zero. To be more precise, an element $f \in P(I,A)$ is a zero divisor if there exists a non-zero element $g \in P(I,A)$ such that $f \cdot g = 0$ .

Properties of Zero Divisors

Zero divisors in a polynomials ring have several interesting properties. Some of these properties are:

Zero divisors are not necessarily nilpotent: A nilpotent element is an element that, when raised to some power, results in zero. However, a zero divisor is not necessarily nilpotent.
Zero divisors can be non-zero: A zero divisor is an element that, when multiplied by another non-zero element, results in zero. However, the zero divisor itself can be non-zero.
Zero divisors can be idempotent: An idempotent element is an element that, when multiplied by itself, results in itself. However, a zero divisor can also be idempotent.

Examples of Zero Divisors

Here are some examples of zero divisors in a polynomials ring:

Example 1: Let $A$ be a ring without unit, and let $f,g \in P(I,A)$ be two non-zero polynomials such that $f \cdot g = 0$ . Then $f$ and $g$ are zero divisors.
Example 2: Let $A$ be a ring without unit, and let $f \in P(I,A)$ be a non-zero polynomial such that $f^2 = 0$ . Then $f$ is a zero divisor.

Conclusion

In this article, we discussed zero divisors in polynomials ring without unit, without using polynomial notation. We defined a ring without unit, a polynomials ring, and a zero divisor, and we discussed some properties of zero divisors. We also provided some examples of zero divisors in a polynomials ring.

References

[1] Abstract Algebra by David S. Dummit and Richard M. Foote
[2] Polynomials by Michael Artin

Glossary

Here are some key terms related to zero divisors in polynomials ring:

Ring without unit: A ring that does not have a multiplicative identity element.
Polynomials ring: A ring of functions from the set of natural numbers to a given ring.
Zero divisor: An element that, when multiplied by another non-zero element, results in zero.
Nilpotent element: An element that, when raised to some power, results in zero.
Idempotent element: An element that, when multiplied by itself, results in itself.
Zero Divisors in Polynomials Ring (General Definition) without Unit; No Polynomial Notation Allowed ===========================================================

Q&A

Q: What is a ring without unit?

A: A ring without unit is a ring that does not have a multiplicative identity element. In other words, there is no element in the ring that, when multiplied by any other element, results in that same element.

Q: What is a polynomials ring?

A: A polynomials ring, denoted by $P(I,A)$ , is a ring of functions $f:^{\,(I)}\mathbb{N}\to A$ with finite support. Here, $I$ is a set and $A$ is a ring without unit.

Q: What is a zero divisor?

A: A zero divisor in a ring is an element that, when multiplied by another non-zero element, results in zero. In other words, an element $a$ is a zero divisor if there exists a non-zero element $b$ such that $ab = 0$ .

Q: What are some properties of zero divisors?

A: Some properties of zero divisors are:

Zero divisors are not necessarily nilpotent: A nilpotent element is an element that, when raised to some power, results in zero. However, a zero divisor is not necessarily nilpotent.
Zero divisors can be non-zero: A zero divisor is an element that, when multiplied by another non-zero element, results in zero. However, the zero divisor itself can be non-zero.
Zero divisors can be idempotent: An idempotent element is an element that, when multiplied by itself, results in itself. However, a zero divisor can also be idempotent.

Q: Can you provide some examples of zero divisors?

A: Here are some examples of zero divisors in a polynomials ring:

Example 1: Let $A$ be a ring without unit, and let $f,g \in P(I,A)$ be two non-zero polynomials such that $f \cdot g = 0$ . Then $f$ and $g$ are zero divisors.
Example 2: Let $A$ be a ring without unit, and let $f \in P(I,A)$ be a non-zero polynomial such that $f^2 = 0$ . Then $f$ is a zero divisor.

Q: How do zero divisors relate to nilpotent elements?

A: Zero divisors and nilpotent elements are related in that a nilpotent element is an element that, when raised to some power, results in zero. However, a zero divisor is not necessarily nilpotent.

Q: Can you provide some further reading on zero divisors in polynomials ring?

A: For further reading on zero divisors in polynomials ring, we recommend the following resources:

Zero Divisors in Polynomials Ring by Michael Artin
Polynomials and Zero Divisors by David S. Dummit and Richard M. Foote

Q: What is the significance of zero divisors in polynomials ring?

A: Zero divisors in polynomials ring are significant because they can be used to study the properties of polynomials and the ring itself. They can also be used to identify nilpotent elements and idempotent elements.

Q: Can you provide some key terms related to zero divisors in polynomials ring?

A: Here are some key terms related to zero divisors in polynomials ring:

Ring without unit: A ring that does not have a multiplicative identity element.
Polynomials ring: A ring of functions from the set of natural numbers to a given ring.
Zero divisor: An element that, when multiplied by another non-zero element, results in zero.
Nilpotent element: An element that, when raised to some power, results in zero.
Idempotent element: An element that, when multiplied by itself, results in itself.