Title: In honour of doctor Volodymyr Tretyak on the occasion of his 50th birthday
Authors: Editorial

Dr. Volodymyr Tretyak is a well-known Ukrainian scientist working in the field of theoretical physics. Volodymyr Ivanovych Tretyak was born on April 24, 1955, in Lviv. In 1972 he entered the Physics department of the Ivan Franko Lviv State University and specialized at the Theoretical Physics chair. There he got the taste for theoretical and mathematical studies under the beneficial influence of brilliant teachers. Volodymyr Tretyak was a constant participant of the seminars of the eminent Ukrainian physicist Roman Gaida devoted to the problems of relativistic physics.