Cartesian Products: Set of Ordered Pairs?

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Discussion Overview

The discussion centers on the concept of the Cartesian product of two sets, specifically whether it is defined as the set of all possible ordered pairs (a, b) where a is an element of set A and b is an element of set B, or simply as the set of all ordered pairs. The scope includes theoretical aspects and semantic clarifications related to set theory.

Discussion Character

  • Conceptual clarification, Debate/contested, Technical explanation

Main Points Raised

  • Some participants propose that the Cartesian product (A × B) should consist of ordered pairs, emphasizing that expressions like "1 cow" are not valid ordered pairs, while "(1, cow)" is.
  • There is a discussion about the semantics of "all possible" versus "all" in the context of ordered pairs, with some participants expressing confusion over these terms.
  • One participant questions whether (1, cow) and (cow, 1) are the same, asserting that Cartesian products are not commutative, as the order of elements matters in the pairs.
  • Another participant acknowledges their misunderstanding and expresses clarity on the concept after further discussion.

Areas of Agreement / Disagreement

Participants generally agree that the Cartesian product consists of ordered pairs, but there is disagreement regarding the interpretation of "all possible" versus "all" ordered pairs, as well as the commutative property of Cartesian products.

Contextual Notes

There are unresolved semantic issues regarding the definitions of "all possible" and "all" in relation to ordered pairs, and the discussion reflects varying interpretations of these terms.

QuantumP7
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Is the cartesian product (A \times B) the set of ALL POSSIBLE ordered pairs (a, b) such that a is an element of A and b is an element of b, or is it simply the set of "all ordered pairs?"
 
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Question for you: A = {1, 2, 3} and B = {cow, sheep}.Write down A x B.
 
{1 cow, 2 cow, 3 cow; 1 sheep 2 sheep 3 sheep}?

So it's all possible ordered pairs?
 
QuantumP7 said:
{1 cow, 2 cow, 3 cow; 1 sheep 2 sheep 3 sheep}?

correct

So it's all possible ordered pairs?

Your question is more a language thing about the word "possible".
 
Yeah, I've gotten hung up on the semantics of all possible vs. all. But I think that I understand what's going on.

But does anyone know what the Venn diagram of a cartesian product set looks like?
 
Outlined said:
correct
Not correct; AxB should consists of ordered pairs.
"1 cow" is not an ordered pair, "(1,cow)" is.
QuantumP7 said:
all possible vs. all.
What is or could be the difference?
 
QuantumP7 said:
Is the cartesian product (A \times B) the set of ALL POSSIBLE ordered pairs (a, b) such that a is an element of A and b is an element of b, or is it simply the set of "all ordered pairs?"

If I understand you about trying to say that for example (1,cow) and (cow,1) are the same, then that is false. Cartesian products are not in general commutative since A x B takes the element of A and then B in the ordered pair. if A and B are the same set then you will have this property ( (a,b) and (b,a) are part of A x B) but generally this is not the case.
 
Landau said:
Not correct; AxB should consists of ordered pairs.
"1 cow" is not an ordered pair, "(1,cow)" is.

You're right. My fault.

What is or could be the difference?

I get it now. All Cartesian products = all products. I think that I was just over-thinking the whole thing. Thanks so much!

chiro said:
If I understand you about trying to say that for example (1,cow) and (cow,1) are the same, then that is false. Cartesian products are not in general commutative since A x B takes the element of A and then B in the ordered pair. if A and B are the same set then you will have this property ( (a,b) and (b,a) are part of A x B) but generally this is not the case.

I see now. Thank you so much.
 

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