Wacław Sierpiński (nonfiction)

Wacław Franciszek Sierpiński.

Wacław Franciszek Sierpiński (Polish: [ˈvat͡swaf fraɲˈt̠͡ɕiʂɛk ɕɛrˈpʲiɲskʲi] (About this sound listen)) (March 14, 1882 – October 21, 1969) was a Polish mathematician. He made important contributions to set theory (research on the axiom of choice and the continuum hypothesis), number theory, theory of functions, and topology.

In 1907 Sierpiński first became interested in set theory when he came across a theorem which stated that points in the plane could be specified with a single coordinate. He wrote to Tadeusz Banachiewicz (then at Göttingen), asking how such a result was possible. He received the one-word reply 'Cantor'. Sierpiński began to study set theory and, in 1909, he gave the first ever lecture course devoted entirely to the subject.

Sierpiński maintained an incredible output of research papers and books. During the years 1908 to 1914, when he taught at the University of Lwów, he published three books in addition to many research papers. These books were The Theory of Irrational Numbers (1910), Outline of Set Theory (1912), and The Theory of Numbers (1912).

When World War I began in 1914, Sierpiński and his family were in Russia. To avoid the persecution that was common for Polish foreigners, Sierpiński spent the rest of the war years in Moscow working with Nikolai Luzin. Together they began the study of analytic sets. In 1916, Sierpiński gave the first example of an absolutely normal number.

When World War I ended in 1918, Sierpiński returned to Lwów. However shortly after taking up his appointment again in Lwów he was offered a post at the University of Warsaw, which he accepted. In 1919 he was promoted to a professor. He spent the rest of his life in Warsaw.

During the Polish–Soviet War (1919–1921), Sierpiński helped break Soviet Russian ciphers for the Polish General Staff's cryptological agency.

In 1920, Sierpiński, together with Zygmunt Janiszewski and his former student Stefan Mazurkiewicz, founded the influential mathematical journal Fundamenta Mathematica. Sierpiński edited the journal, which specialized in papers on set theory.

During this period, Sierpiński worked predominantly on set theory, but also on point set topology and functions of a real variable. In set theory he made contributions on the axiom of choice and on the continuum hypothesis. He proved that Zermelo–Fraenkel set theory together with the Generalized continuum hypothesis imply the Axiom of choice. He also worked on what is now known as the Sierpinski curve.

Sierpiński continued to collaborate with Luzin on investigations of analytic and projective sets. His work on functions of a real variable includes results on functional series, differentiability of functions and Baire's classification.

Sierpiński retired in 1960 as professor at the University of Warsaw, but continued until 1967 to give a seminar on the Theory of Numbers at the Polish Academy of Sciences.

He published over 700 papers and 50 books.

Three well-known fractals are named after him (the Sierpinski triangle, the Sierpinski carpet and the Sierpinski curve), as are Sierpinski numbers and the associated Sierpiński problem.

Fiction cross-reference

• Gnomon algorithm
• Mathematics

Nonfiction cross-reference

• Axiom of choice (nonfiction)
• Jerzy Browkin (nonfiction) - Doctoral student
• Nikolai Luzin (nonfiction)
• Edward Marczewski (nonfiction) - Doctoral student
• Mathematician (nonfiction)
• Stefan Mazurkiewicz (nonfiction) - Doctoral student
• Jerzy Neyman (nonfiction) - Doctoral student
• Stanisław Ruziewicz (nonfiction) - Doctoral student
• Andrzej Schinzel (nonfiction) - Doctoral student
• Set theory (nonfiction)
• Topology (nonfiction)
• Georgy Voronoy (nonfiction) - Doctoral advisor
• Stanisław Zaremba (nonfiction) - Doctoral advisor

External links:

• Wacław Sierpiński @ Wikipedia