Answer to Question #216275 in Algorithms for nurain

Question

2.Find the regular expression defining each of the following language over E=[a,b].

i. All strings that do not end in a double letters.

ii. all strings in which letter never triples

iii. All strings in which 'a' is triple or 'b' is triple.

Answer 1

i) (a + b)*(ab + ba) + a + b + /\
ii)(/\ + b + bb)(a + ab + abb)*
iii) (/\ + b + bb)(a + ab + abb)*aaa(/\ + b + bb)(a + ab + abb)* + (/\ + a + aa)(b + ba + baa)*bbb(/\ + a + aa)(b + ba + baa)*