gate academy, all india mock test 2019

Question

Comments

I am getting option d. Is this correct?

Answer 1

$\text{For the string “$abbcde$”, the Sentential forms are :}$

 

 $\text{A → $\underset{1}{aBDe}$ → $\underset{2}{aBbcDe}$ → $\underset{3}{abbcDe}$ → $\underset{4}{abbcde}$  [Left Sentential Form]}$ 

 

$\text{ A → $\underset{5}{aBDe}$ → $\underset{6}{aBde}$ → $\underset{7}{aBbcde}$ → $\underset{8}{abbcde}$  [Right Sentential Form] } $

 

 

$\underline{\textbf{So Possible Viable Prefixes among the given options are} } :$

$\text{ (i) “aB” in $\textbf{(6)}$ as $\textit{D → d}$ is the Handle}$

$\text{ (ii) “aBBcde” in above Sentential Forms, no such Prefix present, so this is Invalid Viable Prefix}$

$\text{ (iii) “abb” in $\textbf{(4)}$ as $\textit{D → d}$ is the Handle}$

$\text{ (iv) “aBb” in $\textbf{(7)}$ as $\textit{B→ Bbc}$ is the Handle}$

$\text{ (v) “aBbcD” in $\textbf{(2)}$ Handle is $\textit{B→ Bbc}$, so this is also a Invalid Viable Prefix}$

$\text{ (vi) “abbc” in $\textbf{(4)}$ as $\textit{D→ d}$ is the Handle}$

 

${\color {Red} \underline{ \textbf{Good Read}}:}$

$1.$ Viable Prefix, Handle 

$2.$ UGC NET CSE | June 2013 | Part 2 | Question: 22

 

Answer 2

Answer must be C,

the reductions which we are getting while reducing the string abbcde are,

$A => aBDe => aBde => aBbcde => abbcde.$

clearly (ii) and (v) are not viable prefixes.

Answer 3

Option C is correct.

Comments

can you please tell me how many viable prefixes are present here.