Bulgarian Institute of Solid State Physics
Bulgarian Academy of Sciences














Union of the Physicists in Bulgaria

Created: 19.7.2006

(02.01.1883 – 19.09.1967)

Born: in Vratsa


Ivan Tzenoff studied physics and mathematics in the Universities of Sofia (1904 – 1906; 1908), Belgrad (1907), and Zagreb (1907)

Sofia University sent him to specialize in Paris (1911 – 1913) on the area of analytical mechanics. In Sorbonne, he read books of Pol Apell and Anry Pouancare (1854 – 1912) and studied qualitative theory of differential equations for modeling processes in mechanics


He investigated solid bodies with one immovable point (so called holonomic system) with Lagrange equations. His habilitation paper was “Movement of rotating solid, heavy, homogenous body in case of Lagrange”

He described non-holonomic systems (motion around moving center as a wheel of bicycle) by coordinates, time and derivative coordinates and time, and solved problems successfully. The equations for non-holonomic systems called Tzenoff I equations

I. Tzenoff received three new equations, called Tzenov II equations during the 30th of XX century

He propounded gravitational alternative model in 1933

Professional experience:

Head of analytical mechanics department (1914 – 1951)

Head of General and Applied Mathematics (1953 – 1958)

Dean of the Faculty of Physics and Mathematics (1925 – 1926 and 1929 – 1930)

President of the Society of Physicists and Mathematicians in Sofia (1922 – 1945)

Teaching activities:

Professor Ivan Tzenoff lectured Analytical Mechanics (1914 – 1958)


Corresponding members (1925) and member of Bulgarian Academy of Sciences (1929).


    I. Tzenoff, Sur une loi corrective de la loi de Newton pour la determination du deplacement du perihelie et de la deviation des ragons lumineux, L'Enseignement Mathematique, 1932
  1. I. Tzenoff, Sur les equations qu mouvement des systemes comportant un asservissem ent., Annuaire de L'Universite de Sofia, Faculte Physico-Mathematique, 24, 1928, кн. 1

  2. I. Tzenoff, Une forme nouvelle des equations fu mouvement des systemes non holonomes et son application dans la theorie des percussions, Dleft, Executive comm of the Congress, 1925, 11 p.

  3. I. Tzenoff, Sur le mouvement des systemes non holonomes, Journal de mathematiques pures et appliquees (Paris, Gauthier-Villars), t. 4, 1925, facs 2, p. 193-207

  4. I. Tzenoff, Sur les equations du mouvement des systemes materiels non holonomes, Mathematische Annalen (Berlin Springer), Bd. 91, 1924, p. 161-168

  5. I. Tzenoff, Sur les equations generales du mouvement des systemes materiels non holonomes, Journal de mathematiques pures et apliquees (Paris, Gauthier-Villars), t. 3, 1920, Ser. 8, p. 245-264


  1. За трудовете на академика проф. Иван Ангелов Ценов, Математика и физика, 1958, кн. 2, с. 64

  2. Б. Долапчиев, Академик Иван Ценов, Физико-математическо списание, 1958, кн. 3-4, с. 181-184

  3. Академик Иван Ценов - некролог, Списание на ФМД, 1967, с. 240

  4. Б. Долапчиев, Академик Иван Ценов Ангелов, Математика и физика, г. 10, 1967

  5. 100 година БАН (1869-1969), София, БАН (1969) с. 194-196

  6. А. Григорян, Б. Фрадлин, Приносът на академик Ценов и чл. кор. Долапчиев в развитието на аналитичната механика, Годишник на Националния политехнически музей, 1977, т. 7, с. 13-30

  7. И. Чобанов, Иван Ценов (1883-1967) По случай 100 год. от рождението му, Физико-математическо списание, 1983, кн. 4, с. 329-341

  8. И. Чобанов, Иван Ценов, Български математици, София, НП, 1987, с. 82-94

  9. И. Чобанов, Очерк за Иван Ценов, София, Университетско издателство, 1992

  10. Юбилейна научна сесия по случай 100 години от рождението на акад. И. Ценов, Физико-математическо списание, 1983, кн. 1, с. 39