Adélia Sequeira1 and Tomáš Bodnár2

1 CEMAT/IST and Department of Mathematics, Instituto Superior Técnico, Technical University of Lisbon, Portugal (adelia.sequeira@math.ist.utl.pt)
2 Department of Technical Mathematics, Faculty of Mechanical Engineering, Czech Technical University, Prague, Czech Republic (bodnar@marian.fsik.cvut.cz)