Proving Power Set Inclusion: A Simple Proof for A⊆B and P(A)⊆P(B)

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Discussion Overview

The discussion revolves around proving the inclusion of power sets, specifically addressing the claim that if set A is a subset of set B (A ⊆ B), then the power set of A (P(A)) is a subset of the power set of B (P(B)). The scope includes theoretical aspects of set theory and formal proof techniques.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • Some participants suggest starting with the definitions of subsets and power sets to establish the proof framework.
  • One participant proposes beginning the proof with an arbitrary element x from P(A) and questions how to proceed from there.
  • Another participant emphasizes the need for a formal proof for an assignment, indicating the importance of clarity in the argument.
  • There is a repeated inquiry about the nature of x and the sets containing its elements, highlighting a focus on understanding the foundational aspects of the proof.

Areas of Agreement / Disagreement

Participants generally agree on the approach of starting with definitions and the nature of elements in power sets. However, there is no consensus on the specific method to proceed with the proof, as some participants express different inclinations on how to initiate the argument.

Contextual Notes

Limitations include potential misunderstandings of the definitions of subsets and power sets, as well as the need for a formal structure in the proof that remains unresolved in the discussion.

Who May Find This Useful

This discussion may be useful for students studying set theory, particularly those looking for insights into formal proofs involving power sets and subset relations.

im2fastfouru
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This seems like a simple proof but I'm not familiar with power set proofs

If A[tex]\subseteq[/tex]B then P(A) [tex]\subseteq[/tex] P(B)
 
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A good place to start might be with the definitions of a subset and a power set. So the general set A is a subset of another general set B if every element of A is contained in B.

The power set P(A) of a set A is defined as [itex]P(A) = \{X:X\subseteq A\}[/itex], that is the set of all the subsets of A.
 
i'm more inclined to start with x [tex]\in[/tex] P(a), can i start the proof this way?
 
im2fastfouru said:
i'm more inclined to start with x [tex]\in[/tex] P(a), can i start the proof this way?

That's probably a good way.
 
Last edited:
im2fastfouru said:
i'm more inclined to start with x [tex]\in[/tex] P(a), can i start the proof this way?
Why do you say "more inclined"? That was exactly what was suggested.
 
im2fastfouru said:
i'm more inclined to start with x [tex]\in[/tex] P(a), can i start the proof this way?

If [tex]x \in P(A)[/tex] what is x? In particular, what set are all of x's elements in?
 
Last edited:
what is x? In particular, what set are all of x's elements in?

x is just an arbitrary element. And if A [tex]\subseteq[/tex] B then prove P(A) [tex]\subseteq[/tex] P(B). This need to be proved formally as well for my assignment!
 
im2fastfouru said:
x is just an arbitrary element. And if A [tex]\subseteq[/tex] B then prove P(A) [tex]\subseteq[/tex] P(B). This need to be proved formally as well for my assignment!

Sorry, the latex got screwed up. Re-read it now
 

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