Empty set

The empty set $\emptyset$ is the set containing no elements. #m/def/set In $Z F$ its existence is guaranteed by the Emptyset Axiom, and by the Axiom of Extensionality, it is unique. Additionally by vacuity it is a Subset of every set including itself. It is the initial object in $𝖲 𝖾 𝗍$ .

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