Set Theory Proof: A∩B=Ø implies C∩D=Ø

In summary, the conversation is about a question regarding set theory proofs. The conjecture is that if A⊆C, B⊆D, and A∩B=Ø, then C∩D=Ø. However, it is proven to be false with the example of fruit sets. The person asking for help thanks the others for clarifying with the fruit example.
  • #1
dainty77
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0

Homework Statement



Hey guys!

I am new to this forum but saw the helpful posts on set theory proofs and wondered if I could finally get some help with this problem:

Suppose A, B, C, and D are sets with A⊆C and B⊆D. If A∩B=Ø then C∩D=Ø.

This is a biconditional so I have to prove it both ways correct?

Any help would be greatly appreciated!


Homework Equations





The Attempt at a Solution

 
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  • #2
dainty77 said:
Suppose A, B, C, and D are sets with A⊆C and B⊆D. If A∩B=Ø then C∩D=Ø.
Where's the biconditional? I only see an if then, not an if and only if. What work have you done?As stated, the conjecture is false. Are you sure you have the sense correct in terms of which sets are subsets of some other set?
 
  • #3
My mistake, it is an "if then" statement.
 
  • #4
As I previously said, the conjecture as written is false. For example, consider sets of fruits. Let A={apple}, B={banana}, C={apple, orange}, and D={banana, orange}. With this, A⊆C, B⊆D, and A∩B=Ø, but C∩D={orange}, which is not the null set.
 
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  • #5
Wow, the example of using fruit really helped clarify it a lot more. Thank you so much!
 

Related to Set Theory Proof: A∩B=Ø implies C∩D=Ø

1. What is set theory?

Set theory is a branch of mathematics that deals with the study of sets, which are collections of objects or elements. It provides a foundation for other areas of mathematics and is used to analyze and prove mathematical statements.

2. What is a set theory proof?

A set theory proof is a logical argument that uses the principles and rules of set theory to demonstrate the truth of a mathematical statement. It typically involves defining sets, using set operations, and applying axioms and theorems to reach a conclusion.

3. How do I approach a set theory proof?

When approaching a set theory proof, it is important to first understand the definitions, axioms, and theorems that apply to the specific problem. Then, break down the problem into smaller, more manageable parts and use logical reasoning to connect them together to reach a solution.

4. What are some common challenges in set theory proofs?

Some common challenges in set theory proofs include understanding and applying the axioms and theorems correctly, dealing with infinite sets, and working with complex or abstract concepts. It is also important to be precise and rigorous in your reasoning to avoid errors.

5. How can I improve my set theory proof skills?

To improve your set theory proof skills, it is helpful to practice solving various problems and familiarizing yourself with different sets and their properties. It is also beneficial to seek guidance from textbooks, online resources, and experienced mathematicians, and to constantly strive for clarity and precision in your proofs.

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