Giorgi Akhalaia, Grigor Giorgadzea), Valerian Jikia, Neron Kaldani
I.Vekua Institute of Applied Mathematics of I. Javakhishvili Tbilisi State University
Giorgi Makatsaria
Georgian University of St.Andrews
Nino Manjavidze
Georgian Technical University
a)Corresponding Author. email: gia.giorgadze@tsu.ge