Leonida Tonelli
| Leonida Tonelli | |
|---|---|
 |
|
| Born |
19 April 1885 Gallipoli, Apulia, Italy |
| Died | 12 March 1946 (aged 60) Pisa, Italy |
| Nationality | Italian |
| Fields | Mathematics |
| Institutions |
University of Cagliari University of Parma University of Bologna University of Pisa Scuola Normale Superiore |
| Alma mater | University of Bologna |
| Doctoral advisor | Cesare Arzelà |
| Doctoral students | Lamberto Cesari, Guido Stampacchia |
| Known for | Tonelli's theorem |
Leonida Tonelli (19 April 1885 – 12 March 1946) was an Italian mathematician, noted for creating Tonelli's theorem, a variation of Fubini's theorem, and for introducing semicontinuity methods as a common tool for the direct method in the calculus of variations.
Tonelli graduated from the University of Bologna in 1907.
He is one of the founders of Modern Theory of Functions of Real Variables and his work on the Calculus of Variations is a milestone in analysis.
The present writer's father, W. H. Young, used to recall that this very question — what principle can we use as the foundation of the calculus of variations — had been put him by a young Italian mathematician. His reply was a question: "Can you use semicontinuity?" The young Italian was Leonida Tonelli. Semicontinuity was then still a recent concept, known only to a few. In the hands of Tonelli, it became an important tool in a fundamental new approach to the calculus of variations.
O'Connor, John J.; Robertson, Edmund F., "Leonida Tonelli", MacTutor History of Mathematics archive, University of St Andrews.
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