Finite Commutative Ring: Proving Integral Domain w/ No Zero Divisors

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Homework Help Overview

The discussion revolves around proving that a finite commutative ring with no zero divisors is an integral domain, specifically focusing on the existence of a unity element.

Discussion Character

  • Conceptual clarification, Assumption checking, Exploratory

Approaches and Questions Raised

  • Participants explore the implications of the cancellation laws and the properties of nonzero elements in the ring. There is a focus on demonstrating that multiplication by a nonzero element maps the set of nonzero elements to itself.

Discussion Status

The discussion is active, with participants questioning assumptions about closure under multiplication and exploring the implications of the properties of the ring. Guidance has been offered regarding the mapping of nonzero elements, but no consensus has been reached on the approach.

Contextual Notes

There are constraints regarding the assumptions made about the ring's properties, particularly concerning closure under multiplication and the nature of the nonzero elements.

curiousmuch
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Homework Statement


Show that a finite commutative ring with no zero divisors is an integral domain (i.e. contains a unity element)


Homework Equations


If a,b are elements in a ring R, then ab=0 if and only if either a and b are 0.


The Attempt at a Solution


I've been trying to use the cancellation laws.
 
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Let N be the set of all nonzero elements of the ring R. Pick a nonzero element c. Can you show cN=N? Remember N is a finite set.
 
curiousmuch said:
thanks, but we can't assume R is closed under multiplication.

What do you mean? R is a ring. A 'ring' is closed under its multiplication operation.
 
The clue is in post 2. Can you show multiplication by any nonzero element c maps the set of nonzero elements of the ring to itself in a one-to-one manner.
 

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