**Lamberto Cesari** was an Italian mathematician who worked in the United States. He was known for his work on surface area, functions of bounded variation, optimal control and on the stability of dynamical systems.

- After spending this year in Munich, Cesari returned to the Scuola Normale Superiore in Pisa where he taught for the academic year 1935-36 before going to Rome where he spent the two years 1936-38 at the Istituto Nazionale per le Applicazioni del Calcolo.
- Influenced by Picone, Cesari looked at some new research areas while in Rome and he published the significant paper Sulla risoluzione dei sistemi di equazioni lineari per approssimazioni successive Ⓣ(On solving systems of linear equations by successive approximations) in 1937.
- It was in applying his theory to the method discovered von Mises that Cesari was led to the idea of 'polynomial preconditioning'.
- Cesari also proved that the double Fourier series of any BVC function f (x, y) converges almost everywhere to f (x, y), a sharp result.
- In 1938 the Cesaris left Rome and returned to Pisa where Lamberto was appointed as 'professore incaricato' (assistant professor) at the University of Pisa.
- The Cesaris left Pisa in 1942 when Lamberto was appointed to the University of Bologna.
- At the Institute he met Tibor Radó who, like Cesari, had been undertaking research on area theory.
- Radó and Cesari were invited to address the International Congress of Mathematicians in Cambridge, Massachusetts in September 1950 and they presented their paper Applications of area theory in analysis.
- the two-dimensional concepts of bounded variation and absolute continuity devised by L Cesari, T Radó, and P V Reichelderfer and ...
- As Fleming suggests, Cesari was offered a professorship of mathematics at Purdue University, Lafayette, Indiana in 1952.
- Again Cesari was invited to address the International Congress of Mathematicians, this time in Amsterdam in 1954.
- In 1956 Princeton University Press published Cesari's monograph Surface area.
- Cesari's "Surface area'' ...
- Three years later, in 1959, Cesari published the monograph Asymptotic behavior and stability problems in ordinary differential equations.
- In 1960 Cesari was called to the chair of mathematics at the University of Michigan, Ann Arbor.
- During the last few years of his life, Cesari worked on the theory of functions of bounded variation, a field that he himself had pioneered, and its applications to the theory of hyperbolic systems of conservation laws.
- These very welcome features of Cesari's book distinguish it from most other texts on optimal control.
- This is especially true in existence theory in which the ideas of Tonelli are merged with those of Filippov and of Cesari himself to construct a largely unified framework.
- Finally we note that, in collaboration with his wife, Cesari published Mathematics in the Mediterranean: today's view in 1990.
- Perhaps Isotta Cesari's poem which was published in the American Mathematical Monthly gives an idea of part of their home life.

Born 23 September 1910, Bologna, Italy. Died 12 March 1990, Ann Arbor, Michigan, USA.

View full biography at MacTutor

Origin Italy

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive