Question

7. Describe in English the languages accepted by the following FAs: (9 points) a, b a, b i) a, b a, b a, b

Answer 1

Here I am assuming - is start state and + is final state.

(i) First FA will accept all strings that ends with a and are of odd length. Because if even length then for any input it will come back to initial state.

(ii) This is an extension of first case.Since for any input from start state it will come to middle state, So this FA will accept strings of even length and ending with a.

(iii) Since in second state if b is input then it will go to state where FA will stuck.Hence second input must be a.

FA will accept string of type ( e a (e a)ⁿ ) where e can be either a or b.

So FA will accept (e a )ⁿ⁺¹ where e can be either a or b.