Traian Lalescu

Traian Lalescu
Born	12 July 1882 Bucharest, Romania
Died	15 June 1929 (aged 46) Bucharest, Romania
Residence	Romania
Nationality	Romanian
Fields	Mathematician
Institutions	Polytechnic University of Timișoara University of Bucharest
Alma mater	University of Bucharest University of Paris
Doctoral advisor	Émile Picard
Known for	Integral equations

Traian Lalescu (Romanian: [traˈjan laˈlesku]; 12 July 1882 – 15 June 1929) was a Romanian mathematician. His main focus was on integral equations and he contributed to work in the areas of functional equations, trigonometric series, mathematical physics, geometry, mechanics, algebra, and the history of mathematics.

Life

He went to the Carol I High School in Craiova, continuing high school in Roman and Iaşi. After entering the University of Iaşi, he completed his undergraduate studies in 1903 at the University of Bucharest.

He earned his Ph.D. in Mathematics from the University of Paris in 1908. His dissertation, Sur les équations de Volterra, was written under the direction of Émile Picard. In 1911, he published Introduction to the Theory of Integral Equations, the first book ever on the subject of integral equations.

He was a professor at the University of Bucharest, the Polytechnic University of Timișoara (where he was the first rector, in 1920), and the Polytechnic University of Bucharest.

The Lalescu sequence

$L_{n} = \sqrt[n+1]{(n+1)!}-\sqrt[n]{n!}$

$\lim_{n\to\infty} L_{n} = \frac{1}{e}$

Legacy

Bust of Traian Lalescu,
in Timişoara.

There are several institutions bearing his name, including Colegiul Naţional de Informatică Traian Lalescu in Hunedoara and Liceul Teoretic Traian Lalescu in Reşiţa. There is also a Traian Lalescu Street in Timişoara. The National Mathematics Contest Traian Lalescu for undergraduate students is also named after him.

A statue of Lalescu, carved in 1930 by Cornel Medrea, is situated in front of the Faculty of Mechanical Engineering, in Timişoara.

Work

• T. Lalesco, Introduction à la théorie des équations intégrales. Avec une préface de É. Picard, Paris: A. Hermann et Fils, 1912. VII + 152 pp.^[1] JFM entry
• Traian Lalescu, Introducere la teoria ecuaţiilor integrale, Editura Academiei Republicii Populare Romîne, 1956. 134 pp. (A reprint of the first edition [Bucharest, 1911], with a bibliography taken from the French translation [Paris, 1912]). MR 0085450

References

1. Longley, W. R. (1913). "Review: Introduction à la Théorie des Équations intégrales by T. Lalesco and L'Équation de Fredholm et ses Applications à la Physique mathématique by H. B. Heywood and M. Frechét". Bull. Amer. Math. Soc. 19: 236–241. doi:10.1090/S0002-9904-1913-02333-4.

External links

• Traian Lalescu at the Mathematics Genealogy Project
• "Representative Figures of the Romanian Science and Technology"
• (Romanian) "Traian Lalescu", from Colegiul Naţional de Informatică Traian Lalescu, Hunedoara
• (Romanian) "Cine a fost Traian Lalescu?", from Liceul Teoretic Traian Lalescu, Reşiţa
• (Romanian) "Monumentul lui Traian Lalescu (1930)", at infotim.ro
• A Class of Applications of AM-GM Inequality (From a 2004 Putnam Competition Problem to Lalescu’s Sequence) by Wladimir G. Boskoff and Bogdan Suceava, Australian Math. Society Gazette, 33 (2006), No.1, 51-56.