Is {R-Z} a Subring of the Reals?

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Homework Help Overview

The discussion revolves around the set S = {R-Z}, which includes all real numbers that are not integers, and whether this set qualifies as a subring of the real numbers R. Participants are exploring the properties of subrings and the implications of closure under subtraction.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to argue that S is not a subring based on an example involving the number 1/2 and the result of subtracting it from itself. Other participants question the reasoning and the understanding of integer properties among students.

Discussion Status

The discussion is ongoing, with participants expressing differing views on the validity of the original poster's reasoning. There is a focus on clarifying definitions and assumptions regarding integers and the requirements for demonstrating closure in a set.

Contextual Notes

Some participants mention confusion among classmates regarding basic definitions, such as whether zero is considered an integer, and the necessity of using distinct elements to demonstrate closure, which may reflect misunderstandings in the foundational concepts of ring theory.

1800bigk
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Let S = {R-Z}, the set of all reals that are not integers. Is S a subring of R? I think not because 1/2 is in S but 1/2-1/2=0 so S is not closed under subtraction so is not a subring.

is that right?
 
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what do you think? and why do you think it? if i say you are wrong, would you believe me? why or why not?
 
i think I am right, I am asking because some of the kids in my class said zero is not an integer and they said i should of picked two distinct elements to show its not closed but i said it didnt matter.
 
In which class are you learning about rings where the students don't believe that 0 is an integer and believe that you have to pick two distinct elements to show it's not closed?
 

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