Give a context-free description for the language of the well-parenthesized words over $\{(,)\}$ with no occurrence of $((($. For example, $()(())$ and $(((()())))$ are well-parenthesized words, whereas $)($ and $(()$ are not. Nevertheless, $(((()())))$ is not valid since it has occurrences of $((($. One way to define more precisely the language of well-parenthesized words over $\{(,)\}$ is to describe it as the set of words that can be reduced to the empty word by successive applications of the rewrite rule $()\to\lambda$.