Bug in Automaton.load_Pautomac_Automaton() and/or Pautomac format.
In the format used to save automata in the Pautomac archive (not json, nor yaml), the values of initial and final vectors and of weights of transition is implicitly 0 when not specified; which means that we only store non-zero values. The problem is that the set of states and letters is deduced from the encountered transitions and initial/final vector values. In the rare but possible case where the last letter(s) is(are) never associated to a non-zero transition, we then have no possibility of knowing that this symbol exists. This leads to incorrect number of letters on the reloaded automaton. The same problem could happen with states.
to reproduce : Load automaton from file "39.pautomac_model.txt" from Pautomac data archive. the reloaded automaton has 12 letters, but the header of "39.pautomac.train" and Pautomac reports states that problem 39 uses a 14 letters alphabet.