ε-NFA · Regular

Float regex, compiled

@thethinkmachine·version 1·CC BY 4.0·added 28 Sept 2026

The regex [+-]?d+(.d+)? as an ε-NFA, where d stands for any digit — what a regex engine actually builds. ε-jumps make the sign optional; the fraction needs a digit after the dot.

Open in AutomataStudio

The machine as drawn — 5 states, 8 transitions.Every word up to length 4, one row per length in shortlex order, inked where it is accepted. DiagramLanguage

The author’s examples, run

dd → accept+ddd → acceptdd.dd → accept-d.d → acceptd. → reject.dd → reject