[[Set]] # Empty set The **empty set** $\0$ is the set containing no elements. #m/def/set In [[ZF]] 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 and terminal objects|initial object]] in [[Category of sets]]. # --- #state/develop | #lang/en | #SemBr