1. Dept. of Information Engineering, University of Pisa, Italy; alessio.bechini@unipi.it, pietro.delloglio@unifi.it, francesco.marcelloni@unipi.it
2. Dept. of Computer Science, University of Pisa, Italy; alessandro.bondielli@unipi.it
3. Dept. of Philology, Literature and Lingustics, University of Pisa, Italy; alessandro.bondielli@unipi.it