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Mathematics

Finite Automata and the Regular Languages They Recognize

Quick fact

Finite automata can recognize exactly the regular languages, a class that includes all patterns that can be described by regular expressions. Yet they are powerful enough to model the lexical analysis phase of every compiler.

Why this is interesting

You’ve probably used a vending machine that knows the exact sequence of coins and buttons, yet has almost no memory. How can such a simple device decide which strings of actions are 'valid'?