Reactive Systems
A system that changes its actions, outputs and status in response to stimuli from within or outside.
Maintains an ongoing interaction with the environment rather than produce some final value upon termination.
Used in elevator control systems, traffic signal systems, communication protocols etc.
Lexical Analysis in Compilers
Lexical analysis is the process of converting source code into tokens (keywords, identifiers, operators, etc.). Finite Automata are used to recognize these token patterns.
Tokens are defined using regular expressious. Regular expressions are converted into Finite Automata (usually DFA). FA scans the input character by character.
During compilation, the lexical analyzer (scanner) reads the program text and groups characters into meaningful units (aka. tokens). Identifiers, keywords, numeric constants and operators are some examples for tokens.
Pattern Matching
Pattern matching is the process of checking whether a given text contains a specific pattern. Finite Automata can recognize these patterns efficiently.
Patterns are represented as finite automata. Input string is processed one symbol at a time. FA transitions determine pattern recognition.
In many applications, patterns must be detected in large texts. FA-based algorithms allow fast matching without backtracking.
Widely used in text editors, search tools, and compilers.