_:b19598666	<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>	<mw:File/Thumb> .
_:b19598666	<http://www.w3.org/2007/05/powder-s#describedby>	<http://dev.restore.ovi.cnr.it:8890/about/id/https/en.wikiversity.org/wiki/Inversion_(discrete_mathematics)> .