R or R*: Finding the Subsets and Containing Coordinates

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SUMMARY

The discussion centers on the relationship between the sets R (real numbers) and R* (ordered pairs of the form (x,0) where x is in R). It clarifies that R and R* are distinct sets, with R containing the interval [a,b] as a subset, while R* does not. The user seeks to understand which set contains specific elements, particularly in the context of definite integrals of complex-valued functions and k-dimensional Euclidean space. The conclusion is that [a,b] is a subset of R, and the coordinates x_i of a k-dimensional vector are elements of R.

PREREQUISITES
  • Understanding of real numbers and complex numbers
  • Knowledge of definite integrals in calculus
  • Familiarity with k-dimensional Euclidean space concepts
  • Basic set theory terminology
NEXT STEPS
  • Study the properties of real numbers and their subsets
  • Learn about the definite integral of complex-valued functions
  • Explore the structure of k-dimensional Euclidean spaces
  • Review set theory, focusing on the distinction between different types of sets
USEFUL FOR

Mathematicians, students of calculus, and anyone interested in the foundations of real and complex analysis.

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Let R be a set of real numbers derived from rational numbers and R* be a set consisting of all ordered pairs of the form (x,0) where x is contained in R.
Then R* can be identified with R.

I'd like to ask you two questions.

1. Definition of definite integral of complex valued function of real variable.
Let f be a complex valued function of real variable on [a,b] into C where C is the set of complex numbers ; C is the set of all ordered pairs of the form (x,y) with x,y contained in R.
Let f(t)= f_1(t) + i * f_2(t)
Then the definite integral of f is defined as follows
; integral of f(t) from a to b = integral of f_1(t) from a to b + i * integral of f_2(t) from a to b.
What I want to know is that which set between R and R* has [a,b] as its subset.

2. Definition of k-dimensional Euclidean space.
Let J(k) be the k-dimensional Euclidean space.
Then , if x is contained in the Euclidean space, x= (x_1,x_2,...,x_k).

I'd like to know that which set between R and R* contains a coordinate x_i of x where i runs from 1 to k.
 
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I have absolutely know clue what you mean by "which set between R and R*". R and R* are distinctly different sets and there is no set "between" them.
 
HallsofIvy said:
I have absolutely know clue what you mean by "which set between R and R*". R and R* are distinctly different sets and there is no set "between" them.

I'm sorry to confuse you.
I'm living a country where English is not a first language.(I'm not good at speaking english)
So, I hope you to try to understand my mistakes.
Of course, there is no set "between" them.
i'll try to explain it by another way.

In question 1,
let A be a statement such that [a,b] is a subset of R,
and let B be a statement such that [a,b] is a subset of R*.
In these two cases A,B, which case is true? is it A? or is it B?

In question 2,
let A' be a statement such that x_i is an element of R,
and let B' be a statement such that x_i is an element of R*.
In these two cases A',B', which case is true? which statement is true?
is it A'? or is it B'?

I really hope this additional explanation help you to understand my question.
Thanks.
 

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