This C++ code, available at http://www.diegm.uniud.it/elettrotecnica/web/thinit/, is copyrighted from 2013 by Prof. Ruben Specogna and Prof. Paweł Dłotko. It is a topology-preserving thinning for three-dimensional simplicial complexes. More informations about this algorithm and about the theory behind it may be found in the paper
P. Dłotko, R. Specogna
"Topology preserving thinning for cell complexes"
IEEE Transactions on Image Processing, Vol. 23, No. 10, pp. 4486-4495, 2014, regular paper.