Consider the language over the alphabet {a,b} which consists of any strings with exactly two as. There is no restriction on the number or position of bs. Thus a string with one a should be rejected and a string with three as should be rejected; 4 and any higher number is
right out. What are the Myhill-Nerode equivalence classes for this language? More precisely, if we call this language L there is an equivalence relation R_L. How many equivalence classes does this relation have and what are they? Use these equivalence classes to construct the minimal DFA for the language.