| Metamath Proof Explorer |
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Related theorems GIF version |
| Description: Extend wff notation to include transitive classes. Notation from [TakeutiZaring] p. 35. |
| Ref | Expression |
|---|---|
| cA | class A |
| Ref | Expression |
|---|---|
| wtr | wff Tr A |
| Colors of variables: wff set class |