4. Any string of terminals that can be generated by the following CFG- S à XY X à aX | bX | a Y à Ya | Yb | a a) Has at least one b b) Should end in an a c) Has no consecutive a’s or b’s d) Has at least two a’s

Question

4. Any string of terminals that can be generated by the following CFG-          S   à XY           X  à aX | bX | a          Y  à Ya | Yb | a  a)      Has at least one b b)      Should end in an a c)      Has no consecutive a’s or b’s d)      Has at least two a’s

anonymous · Answer

One way to solve this question is to look at the answers and try to disprove them. 

For example, if you can find a word (within the grammar) that has no 'b' at all, 'a)' would obviously be false. Try to figure out if you can make such a word and do the same for all other answers.

In the end, you'll have one answer that you cannot disprove.