Metamath Proof Explorer

Syntax definition wbr

Description: Extend wff notation to include the general binary relation predicate. Note that the syntax is simply three class symbols in a row. Since binary relations are the only possible wff expressions consisting of three class expressions in a row, the syntax is unambiguous. (For an example of how syntax could become ambiguous if we are not careful, see the comment in cneg .)

Ref Expression
Assertion wbr wff A R B