Pseudo-minimal automata ([1],[2]) are minimal acyclic automata that have a proper element (a transition or a state) for each word belonging to the language of the automaton. That proper element is not shared with any other word, and it can be used for implementing a function on words belonging to the language. For instance, dynamic perfect hashing (e.g. a mapping from n unique words to n consecutive numbers, such that addition of new elements does not change the order of the previous elements) can be implemented using a pseudo-minimal automaton ([3]).