TA ASSIGNMENT 2 PART 1

Theory of Automata

Assignment #2

Part #1

Regular Expression # 1

The set of strings over {A..Z,a..z} that contain the word "main".

Let <letter> = A | B | ... | Z | a | b | ... | z <letter>* main <letter>*

Regular Expression # 2

The set of strings over {A..Z,a..z} that contain 3 x's.

<letter>* x <letter>* x <letter>* x <letter>*

Regular Expression # 3

The set of strings over {a,b} that even number of a's and odd number of b's.

((a+b)(a+b))*b+(b)((a+b)(a+b))*

Regular Expression # 4

The set of strings over {a,b} that contain no combination of ba

a*b*

Regular Expression # 5

The set of strings over {a,b} that contain consecutive two ab
(a+b)*abab(a+b)*