Question

Consider the context-free grammar
$E\to E+E$
$E\to (E*E)$
$E\to \mathrm{id}$
where E is the starting symbol, the set of terminals is {id, (, + ,), *} and the set of non-terminals is {E}.

Which of the following terminal strings has more than one parse tree when parsed according to the above grammar?

• A. id + (id* (id * id))
• B. (id* (id * id)) + id
• C. id + id + id + id
• D. ((id * id + id) * id)

Answer 1

The correct option is C id + id + id + id


$\therefore$ id + id+id+id has more than one parse tree.