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Metamath Proof Explorer


Theorem eumo

Description: Existential uniqueness implies uniqueness. (Contributed by NM, 23-Mar-1995)

Ref Expression
Assertion eumo ∃! x φ * x φ

Proof

Step Hyp Ref Expression
1 df-eu ∃! x φ x φ * x φ
2 1 simprbi ∃! x φ * x φ