1. Faculty of Mathematics and Physics, Charles University in Prague, Malostranské nám. 25, 118 00 Praha 1, Czech Republic. E-mail: toknap@gmail.com
2. Semantic Web Company, Neubaugasse 1, 1070 Vienna, Austria. E-mail: tomas.knap@semantic-web.com
3. EEA s.r.o, Hattalova 12B, 831 03 Bratislava, Slovak Republic. E-mail: peter.hanecak@eea.sk
4. TenForce bvba, Havenkant 38, 3000 Leuven, Belgium. E-mail: bert.van.nuffelen@tenforce.com