Equivalence with Finite Automata


What does is mean to say that Regular Expressions
and Finite Automata are equivalent?


Why is it surprising that Regular Expressions
and Finite Automata are equivalent? 


How do you show that Regular Expressions
and Finite Automata are equivalent?

















How do you build a machine for each part of a Regular Expression?

	1. R = a

	2. R = epsilon

	3. R = empty-set

	4. R = R1 | R2

	5. R = R1 R2

	6. R = R1*

Construct an NFA that is equivalent to the Regular Expression.

	a(a|b)*b

















Classwork
(You may work with a partner.)

Construct an NFA that is equivalent to the Regular Expression.


	a*b|a

















How can you use this construction in a practical application?


	give a Regular Expression defining strings to be found
	convert expression to NFA
	convert NFA to DFA
	use the DFA in a matching application