There is a mechanical way to produce operator-precedence relations from an operator grammar. including those with many different nonterminals. Define leading (A) for nonterminal A to be the set of terminals a such that a is the leftmost terminal in some string derived from A. and define trailing (A) to be the set of terminals that can be the rightmost in a string derived from A. Tben for terminals a and b. we say a .,; b if there is a right side of the form au(3.b")'. where (3. is either empty or a single nonterminal, and a and 'Yare arbitrary. We say a b if there is a right side of the form «Abf3.. and lJ is in trailing (A ). •n both cases. a and 13 are arbitrary slrings, Also. $