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| Mirrors > Home > NFE Home > Th. List > wnf | GIF version | ||
| Description: Extend wff definition to include the not-free predicate. | 
| Ref | Expression | 
|---|---|
| wph | wff φ | 
| vx | setvar x | 
| Ref | Expression | 
|---|---|
| wnf | wff Ⅎxφ | 
| Colors of variables: wff setvar class | 
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