# Regular Expressions that converts into unambiguous automata

Brüggemann-Klein and Wood (1992) proved that a certain kind of regular expressions, that they call “Deterministic Regular expressions”, when converted into automata using the Glushkov's Construction, generate a DFA. Also, all the expressions that generate a DFA via this algorithm are in this class.

Is something known about classes of regular expression that when given as input to some conversion algorithm to automata (Thompson, Glushkov, any algorithm that gives a NFA or $$\varepsilon$$-NFA in the general case) we get a unambiguous automaton (A NFA such that for every word in the language, only exists one acceptation run)?