Question

Find grammars for ∑= {a, b} that generates the sets of:

a. all strings with no more than three a's
b. all strings with at least three a's
c. all strings with at least two a's

Answer 1

To generate strings with no more than three a's, you can use a grammar with production rules.

Step-by-step explanation:

To find a grammar that generates the set of strings with no more than three a's, we can use regular expressions or production rules. One possible grammar is:

S -> A|B|C|ε
A -> aA|ε
B -> bB|aB|ε
C -> bC|ε

In this grammar, the start symbol is S. A generates strings with no a's, B generates strings with 1-3 a's, and C generates strings with more than three a's. The epsilon symbol represents an empty string.