Authors
Galina Bogdanova
Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Sofia, Bulgaria
Todor Todorov
Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Sofia, Bulgaria
Veliko Tarnovo University “St. Cyril and St. Methodius”, Veliko Tarnovo, Bulgaria
Galya Georgieva-Tsaneva
Institute of Robotics, Bulgarian Academy of Sciences, Sofia, Bulgaria
