GATE Overflow Test Series | Compiler Design | Test 1 | Question: 2

Question

Suppose we have a rightmost derivation which proceeds as follows:

$\begin{array}{ccc}S &\rightarrow & Aabw\\ & \rightarrow &ABw \end{array}$

Which of the following is a possible handle for it?

• A. $\begin{array}{ccc} A &\rightarrow & ab \end{array}$
• B. $\begin{array}{ccc} A &\rightarrow & a\end{array}$
• C. $\begin{array}{ccc} S &\rightarrow & A\end{array}$
• D. $\begin{array}{ccc} B &\rightarrow & ab \end{array}$

Answer 1

In the rightmost derivation in reverse, $B$ is being replaced by $ab$ or $"ab"$ is reduced using the production $B \to ab.$ So, $B \to ab$ is the handle.