Finding the Intersection of Infinite Sets: A Basic Set Theory Question

In summary, the conversation discusses finding the intersection of a series of sets, represented by A(i), where the elements of each set are bounded by 0 and a variable i. The speaker suggests using mathematicasque notation to express this problem, and concludes that the intersection of all A(i) is {0}.
  • #1
semidevil
157
2
ok, find the intersection of i=1 to infinitie of A(i).

A(i) = [0, to 1/i].

I don't understand what it is asking. what do they mean to find the intersection of that?

and what if A(i) = [0, 1/n)
 
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  • #2
To use mathematicasque notation, Intersect[A(i), {i,1,oo}] is the set of all points in each A(i). There's only one point in all A(i)'s: 0. Therefore the intersection is {0}. Same with the second one. But if they made it (0,1/i) then it would be empty.
 
  • #3
Do you mean:

[tex]\bigcap_{i=1}^{\infty} A(i)[/tex]

where A(i) = [0, 1/i]? Wouldn't the answer be {0}?
 

1. What is basic set theory?

Basic set theory is a branch of mathematics that deals with the study of sets, which are collections of objects. It is used to define and analyze relationships between sets and their elements.

2. What are the fundamental concepts of set theory?

The fundamental concepts of set theory include elements, subsets, unions, intersections, and cardinality. Elements are the individual objects within a set, subsets are sets contained within a larger set, unions combine two or more sets, intersections identify the common elements between two sets, and cardinality refers to the number of elements in a set.

3. How are sets represented in set theory?

Sets can be represented in set theory using various methods, such as roster notation, set-builder notation, and Venn diagrams. Roster notation lists the elements of a set within curly braces, set-builder notation describes the properties of the elements within a set, and Venn diagrams use circles to visually represent the relationships between sets.

4. What is the difference between a finite and infinite set?

A finite set is a set with a specific number of elements that can be counted and listed, while an infinite set has an uncountable number of elements. For example, the set of all even numbers is infinite because it continues on indefinitely, while the set {1,2,3} is finite because it has a specific number of elements (3).

5. How is set theory applied in other fields?

Set theory has many applications in various fields, including computer science, statistics, and linguistics. In computer science, set theory is used to design databases and algorithms. In statistics, set theory is used to define probability and analyze data sets. In linguistics, set theory is used to study language and analyze the relationships between words and concepts.

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