Single Idea 13200

[catalogued under 4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set]

Full Idea

Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ. A man with an empty container is better off than a man with nothing.

Gist of Idea

Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ

Source

Herbert B. Enderton (Elements of Set Theory [1977], 1.03)

Book Reference

Enderton,Herbert B.: 'Elements of Set Theory' [Posts + Telecoms 2006], p.3

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