What Are the Elements of P(P(∅))?

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SUMMARY

The discussion centers on the mathematical concept of the power set, specifically P(P(∅)). The user correctly identifies the inner power set as {{∅}, ∅}, but miscalculates the outer power set, which should yield only two elements: {∅} and ∅. The confusion arises from the distinction between elements and subsets of the empty set, ∅, which has no elements but one subset: itself.

PREREQUISITES
  • Understanding of set theory concepts, particularly power sets.
  • Familiarity with the empty set (∅) and its properties.
  • Knowledge of mathematical notation and terminology related to sets.
  • Basic comprehension of subsets and their definitions.
NEXT STEPS
  • Study the definition and properties of power sets in set theory.
  • Explore examples of power sets with non-empty sets for comparison.
  • Learn about the implications of the empty set in various mathematical contexts.
  • Investigate the relationship between elements and subsets in set theory.
USEFUL FOR

Students of mathematics, particularly those studying set theory, educators teaching foundational concepts, and anyone seeking clarity on power sets and the properties of the empty set.

Bashyboy
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Homework Statement


P(P(∅))


Homework Equations





The Attempt at a Solution


I did the inner power set first: {{∅}, ∅}
Then I took the power set of that: {{{∅}}, {∅}, {{∅}, ∅}, ∅}
But according to the answer, there is only two elements.
 
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That first power set doesn't look quite right to me.

is {∅} an element of ∅??

What are all the elements of ∅?

What are all the subsets of ∅?
 

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