https://en.wikipedia.org/wiki/Deterministic_finite_automaton https://en.wikipedia.org/wiki/Deterministic_finite_automaton https://en.wikipedia.org/wiki/Nondeter

https://en.wikipedia.org/wiki/Deterministic_finite_automaton https://en.wikipedia.org/wiki/Deterministic_finite_automaton https://en.wikipedia.org/wiki/Nondeterministic_finite_automaton https://en.wikipedia.org/wiki/Nondeterministic_finite_automa... Said another way: a state machine. True regular languages can be defined by a simple state machine, which is relatively much faster than the extended regular-like language that perl exposes.