Now, we've seen the constructions of regular expressions and finite automata for the purpose of recognizing regular languages.
The following table illustrates a comparison between approaches:
| Regular expression | DFA |
|---|---|
| Concise to express in written form | Is best expressed as a diagram, which has an involved construction |
| Recognition is hard, as it requires deep inspection and mental trial / error | Recognition is systematic and fairly straightforward to construct |
Because regular expressions are easier to express in written (string) form, but harder to use directly to recognize strings, we will need some way to convert a regular expression into a finite automaton. We will subsequently show this construction and will also show that DFAs are as expressive as NFAs and ε-NFAs in terms of the languages they recognize.
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Copyright © 2017 Brendan Rollinson-Lorimer