Department of Mathematics and Computer Science, University of Udine, Udine 33100, Italy. fnadalin@appliedgenomics.org|Department of Mathematics and Computer Science, University of Udine, Udine 33100, Italy. fnadalin@appliedgenomics.org|Department of Mathematics and Computer Science, University of Udine, Udine 33100, Italy. fnadalin@appliedgenomics.org