Define R/Q: How to Add in Quotient Groups

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The discussion revolves around defining the set R\Q under addition and understanding its properties, particularly regarding cosets and disjoint sets. Participants express confusion about how to describe disjoint cosets in R\Q, especially since the sets can repeat when considering bounded intervals. The conversation highlights that while R\Z can be defined with disjoint sets, a similar clear description for R\Q is elusive. There is also a mention of the challenges in counting real numbers and the uniqueness of representations when combining integers or rationals with real numbers. Overall, the thread seeks clarity on the structure and representation of these quotient groups.
matness
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how to define R\Q?(under addition)
R\Q={a+Q:? <a<?}
a€R but if it is not bounded then it will repeat
please help me
n
 
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you define [x]+[y] to be [x+y] wehre [z] means the equivalence class of y (ie the coset y+Q)
 
quotient group is the set of cosets y+Q but if i take y€R the sets begin to repeat (it is a cyclic group, isn't it?)i
for example R\Z ={x+Z: 0<x<1} is set of disjoint sets
so can we also find conditions for y to be disjoint and nice?
 
of course the groups isn't cyclic, it isn't even countable os can't have a singel generator. i struggle to understand your question. what "sets" begin to repeat? plus all cosets are disjoint or equal. do you simply want a "nice" way of describing the equivalence classes? i doubt there is one.
 
mattgrime:<do you simply want a "nice" way of describing the equivalence classes?>
probably. sorry for misremembering the defn for cyclic groups

what i want to know is a description for set of disjoint (but not same) cosets such that their union is real numbers.

the R\Q question crossed my mind because of the description R\Z ={x+Z: 0<x<1} if x were bounded as 0<x<2 some of the elements of the R\Z would be same That is what i mean by "repetition".
but i could'nt describe a set for R\Q in the same way

All of these seemed to me related to counting. when counting real numbers(it is a bit utopian) adding a number € Z and a real number between 0 and 1 is enough. (e.g. 3.4=3+0.4 and this representation is unique using this method)
but same method using rational numbers does not work ,
can we say adding a number € Q and an irrational number between 0 and 1 is enough .
(a real number is more than enough)

thanks in advance
 
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