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| Mirrors > Home > ILE Home > Th. List > weu | GIF version | ||
| Description: Extend wff definition to include existential uniqueness ("there exists a unique 𝑥 such that 𝜑"). | 
| Ref | Expression | 
|---|---|
| wph | wff 𝜑 | 
| vx | setvar 𝑥 | 
| Ref | Expression | 
|---|---|
| weu | wff ∃!𝑥𝜑 | 
| Colors of variables: wff set class | 
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