Show Set Theory Subset Relationship: x, y $\in$ B

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SUMMARY

The discussion focuses on demonstrating that the set ##\{ \{x\}, \{x,y\} \}## is an element of the power set of the power set of set ##B##, denoted as ##\mathcal{P} \mathcal{P} B##. It establishes that since both ##x## and ##y## are members of set ##B##, the individual sets ##\{x\}## and ##\{x,y\}## are subsets of ##B##. Consequently, by the definition of a power set, the set ##\{ \{x\}, \{x,y\} \}## qualifies as a subset of the power set of ##B##, confirming that ##\{ \{x\}, \{x,y\} \} \in \mathcal{P} \mathcal{P} B##.

PREREQUISITES
  • Understanding of set theory concepts, specifically power sets.
  • Familiarity with the notation and definitions of subsets.
  • Basic knowledge of mathematical logic and proofs.
  • Experience with membership relations in set theory.
NEXT STEPS
  • Study the definition and properties of power sets in detail.
  • Explore the concept of subsets and their relationships within set theory.
  • Learn about the implications of membership relations in advanced set theory.
  • Investigate examples of power sets with different types of sets for practical understanding.
USEFUL FOR

Students of mathematics, particularly those studying set theory, educators teaching foundational concepts in mathematics, and anyone interested in formal proofs involving subsets and power sets.

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Homework Statement


Assume that ##x## and ##y## are members of a set ##B##. Show that ##\{ \{x\}, \{x,y\} \} \in \mathcal{P} \mathcal{P} B##

Homework Equations

The Attempt at a Solution


I know that ##\{ \{x\}, \{x,y\} \} \in \mathcal{P} \mathcal{P} B## iff ##\{ \{x\}, \{x,y\} \} \subseteq \mathcal{P} B##, but I don't see where this gets me. To me it's obviously true, but I don't see how to show it.
 
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If something seems obvious, just see if you can use the basic definitions to state it. State the definition of power set and start there.
Since x and y ∈ B, {x} and {x,y} are subsets of B. By the definition of the power set ...
 
FactChecker said:
If something seems obvious, just see if you can use the basic definitions to state it. State the definition of power set and start there.
Since x and y ∈ B, {x} and {x,y} are subsets of B. By the definition of the power set ...
Oh, right. That seems really obvious now. So the power set of B is the set of all subsets. Since ##\{x\}## and ##\{x,y\}## are subsets of B, the set ##\{ \{x\}, \{x,y\} \}## must be a subset of the power set.
 

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