Set Relation Question | PDF Guide

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Discussion Overview

The discussion revolves around the interpretation of set notation, specifically the meaning of A_k B_k, and its implications in the context of set theory. Participants explore concepts related to intersections, unions, and the use of De Morgan's laws within a mathematical framework.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that A_k B_k denotes the intersection of sets A_k and B_k, while others suggest it could represent the Cartesian product.
  • One participant mentions a mix of new and old notation, indicating that multiplication represents intersection and addition represents union.
  • There is a discussion about the relationship between C_complement and C, suggesting that their sum gives the union of all A_k sets, which is considered the 'universe' for the context of the sets.
  • Questions are raised regarding whether the sets are meant to be disjoint and the need for additional information to simplify the problem.
  • Another participant acknowledges the utility of De Morgan's laws in addressing negation questions and expresses confidence in the theorem being discussed.

Areas of Agreement / Disagreement

Participants express differing views on the notation A_k B_k, with no consensus reached on its meaning. The discussion remains unresolved regarding the implications of the sets' relationships and the necessary information for solving the problem.

Contextual Notes

Participants note the potential need for more information about the context of the sets and whether they are disjoint, which could affect the interpretation of the problem.

dimitri151
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See attached pdf.
 

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Hi there.

I'm a little confused with the notation. Does A_k B_k mean the cartesian product between A_k and B_k?
 
No, it means the intersection (sorry I'm using a mix of new notation and an old style notation where the intersection of two sets is shown as multiplication and the union is like addition).
 
dimitri151 said:
No, it means the intersection (sorry I'm using a mix of new notation and an old style notation where the intersection of two sets is shown as multiplication and the union is like addition).

Just looking at the relationship adding up C_complement and C together give the union of all 'A's for index 1 to n which also give the 'universe' and the context for the sets A_k and B_k

Have you been given any other information about the context of the sets? Is each set meant to be disjoint from one another?

You've probably done this but typically what comes to mind in negation questions is to use De-Morgans theorems and the theorems of set algebra, collect terms, simplify etc, but yeah I can see why this is tripping you up.

Hopefully it gives a few more constraints that can be used to simplify the problem because personally I think you need more information to solve it, but I could be wrong.
 
Thank you for the reply. Of course I tried Demorgans laws. The theorem is a really great theorem otherwise I wouldn't waste so much time on it. I'll post it verbatim when I get the chance. Your suggestion is helpful because it shows that the union of the A_k's equals the universe. I think that's one of the statements in the theorem to be proved.
 

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