Czesław Ryll-Nardzewski (; 7 October 1926 – 18 September 2015) was a Polish
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, mathematical structure, structure, space, Mathematica ...
.
Life and career
Born in
Wilno,
Second Polish Republic
The Second Polish Republic, at the time officially known as the Republic of Poland, was a country in Central and Eastern Europe that existed between 7 October 1918 and 6 October 1939. The state was established in the final stage of World War I ...
(now Vilnius,
Lithuania
Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, P ...
), he was a student of
Hugo Steinhaus. At the age of 26 he became professor at
Warsaw University. In 1959, he became a professor at the
Wrocław University of Technology. He was the advisor of 18 PhD theses.
His main research areas were
measure theory
In mathematics, the concept of a measure is a generalization and formalization of geometrical measures (length, area, volume) and other common notions, such as magnitude (mathematics), magnitude, mass, and probability of events. These seemingl ...
,
functional analysis
Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (for example, Inner product space#Definition, inner product, Norm (mathematics ...
,
foundations of mathematics
Foundations of mathematics are the mathematical logic, logical and mathematics, mathematical framework that allows the development of mathematics without generating consistency, self-contradictory theories, and to have reliable concepts of theo ...
and
probability theory
Probability theory or probability calculus is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expre ...
. Several theorems bear his name: the
Ryll-Nardzewski fixed point theorem,
[ “9. Theorem of Ryll-Nardzewski” (p. 171), “(9.6) Theorem (Ryll-Nardzewski)” (p. 174)] the
Ryll-Nardzewski theorem[ See Theorem 7.3.1][ Cf. (2.10)] in
model theory
In mathematical logic, model theory is the study of the relationship between theory (mathematical logic), formal theories (a collection of Sentence (mathematical logic), sentences in a formal language expressing statements about a Structure (mat ...
, and the
Kuratowski and Ryll-Nardzewski measurable selection theorem.
[ See Theorem 6.9.3 on p. 36 and the historical comment on p. 441]
He became a member of the
Polish Academy of Sciences
The Polish Academy of Sciences (, PAN) is a Polish state-sponsored institution of higher learning. Headquartered in Warsaw, it is responsible for spearheading the development of science across the country by a society of distinguished scholars a ...
in 1967.
He died in 2015 at the age of 88
[Zmarł Profesor Czesław Ryll-Nardzewski]
and he is buried in
Wrocław
Wrocław is a city in southwestern Poland, and the capital of the Lower Silesian Voivodeship. It is the largest city and historical capital of the region of Silesia. It lies on the banks of the Oder River in the Silesian Lowlands of Central Eu ...
at .
References
Short biographyat the Polish Academy of Sciences
1926 births
2015 deaths
Model theorists
Scientists from Vilnius
People from Wilno Voivodeship (1926–1939)
Polish mathematicians
Recipients of the State Award Badge (Poland)
{{Poland-mathematician-stub