Traian Lalescu (; 12 July 1882 – 15 June 1929) was a
Romania
Romania ( ; ro, România ) is a country located at the crossroads of Central, Eastern, and Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, Moldova to the east, and ...
n
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change.
History
...
. His main focus was on
integral equations
In mathematics, integral equations are equations in which an unknown function appears under an integral sign. In mathematical notation, integral equations may thus be expressed as being of the form: f(x_1,x_2,x_3,...,x_n ; u(x_1,x_2,x_3,...,x_n) ...
and he contributed to work in the areas of
functional equation
In mathematics, a functional equation
is, in the broadest meaning, an equation in which one or several functions appear as unknowns. So, differential equations and integral equations are functional equations. However, a more restricted meaning ...
s,
trigonometric series
In mathematics, a trigonometric series is a infinite series of the form
: \frac+\displaystyle\sum_^(A_ \cos + B_ \sin),
an infinite version of a trigonometric polynomial.
It is called the Fourier series of the integrable function f if the ter ...
,
mathematical physics
Mathematical physics refers to the development of mathematical methods for application to problems in physics. The ''Journal of Mathematical Physics'' defines the field as "the application of mathematics to problems in physics and the developmen ...
,
geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...
,
mechanics
Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects r ...
,
algebra
Algebra () is one of the broad areas of mathematics. Roughly speaking, algebra is the study of mathematical symbols and the rules for manipulating these symbols in formulas; it is a unifying thread of almost all of mathematics.
Elementary ...
, and the
history of mathematics
The history of mathematics deals with the origin of discoveries in mathematics and the mathematical methods and notation of the past. Before the modern age and the worldwide spread of knowledge, written examples of new mathematical developments ...
.
Life
He went to the
Carol I High School in
Craiova
)
, official_name = Craiova
, image_skyline =
, image_caption = From left: Dolj County Prefecture • Constantin Mihail Palace • Bibescu Manor House • Carol I National College • Museum of Oltenia • University of Craio ...
, continuing high school in
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a letter ...
, and graduating from the
Boarding High School in
Iași
Iași ( , , ; also known by other #Etymology and names, alternative names), also referred to mostly historically as Jassy ( , ), is the second largest city in Romania and the seat of Iași County. Located in the historical region of Western M ...
. After entering the
University of Iași, he completed his undergraduate studies in 1903 at the
University of Bucharest
The University of Bucharest ( ro, Universitatea din București), commonly known after its abbreviation UB in Romania, is a public university founded in its current form on by a decree of Prince Alexandru Ioan Cuza to convert the former Princely ...
.
He earned his
Ph.D. in Mathematics from the
University of Paris
The University of Paris (french: link=no, Université de Paris), Metonymy, metonymically known as the Sorbonne (), was the leading university in Paris, France, active from 1150 to 1970, with the exception between 1793 and 1806 under the French Revo ...
in 1908. His dissertation, ''Sur les
équations de Volterra'', was written under the direction of
Émile Picard
Charles Émile Picard (; 24 July 1856 – 11 December 1941) was a French mathematician. He was elected the fifteenth member to occupy seat 1 of the Académie française in 1924.
Life
He was born in Paris on 24 July 1856 and educated there at th ...
. In 1911, he published ''Introduction to the Theory of Integral Equations'', the first book ever on the subject of
integral equation
In mathematics, integral equations are equations in which an unknown function appears under an integral sign. In mathematical notation, integral equations may thus be expressed as being of the form: f(x_1,x_2,x_3,...,x_n ; u(x_1,x_2,x_3,...,x_n) ...
s.
After returning to Romania in 1909, he first taught Mathematics at the
Ion Maiorescu Gymnasium in
Giurgiu
Giurgiu (; bg, Гюргево) is a city in southern Romania. The seat of Giurgiu County, it lies in the historical region of Muntenia. It is situated amongst mud-flats and marshes on the left bank of the Danube facing the Bulgarian city ...
. From 1909 to 1910, he was a teaching assistant at the
School of Bridges and Highways, in the department of graphic statistics.
He was a professor at the
University of Bucharest
The University of Bucharest ( ro, Universitatea din București), commonly known after its abbreviation UB in Romania, is a public university founded in its current form on by a decree of Prince Alexandru Ioan Cuza to convert the former Princely ...
, the
Polytechnic University of Timișoara
Polytechnic is most commonly used to refer to schools, colleges, or universities that qualify as an institute of technology or vocational university also sometimes called universities of applied sciences.
Polytechnic may also refer to:
Educatio ...
(where he was the first
rector
Rector (Latin for the member of a vessel's crew who steers) may refer to:
Style or title
*Rector (ecclesiastical), a cleric who functions as an administrative leader in some Christian denominations
*Rector (academia), a senior official in an edu ...
, in 1920), and the
Polytechnic University of Bucharest.
The Lalescu sequence
: