Regular Expressions

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In this class, We discuss Regular Expressions.

The Reader should have prior knowledge of finite automata and basic terminology. Click Here.

In our last class, we discussed language. We refresh the concept once and discuss regular expressions.

Language: A language is a set of strings taken from a given alphabet.

Language of a machine: is a language defined by a machine.

Example: Take the alphabet Σ = {a,b}.

L= set of strings contain last two characters 11.

The below-given diagram is the finite automata for the language L.

Finite automata are the graphical way to represent the language.

Similarly, regular expressions are the mathematical way to represent the language.

L(r) is (0+1)*11.

The above mention regular expression will generate the strings containing the last two characters 11.

How we write regular expressions is discussed in our next classes.

Point to understand: Regular expressions are the mathematical way to represent the language.