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Rózsa Péter: Founder of Recursive Function Theory

Rózsa Péter: Founder of Recursive Function Theory


Born: Budapest, Hungary, February 17, 1905
Died: Budapest, Hungary, February 16, 1977

Rózsa Péter (originally Politzer) grew up in a country torn by war and civil strife in which simply living from day to day was never easy. She made major contributions to mathematical theory for which she received some recognition in her lifetime, but her name, which should be written together with the names of the founders of computational theory (Gödel,Turing, Church, Kleene), is all but forgotten today. In this, she no doubt shares the fate of other Eastern European scientists of the same period. "No other field can offer, to such an extent as mathematics, the joy of discovery, which is perhaps the greatest human joy,"* said Rózsa Péter in her lectures to general audiences, which were often titled "Mathematics is Beautiful." In the mouth of another, this might be a naive effusion; for her, it was hard-won wisdom.

Péter enrolled at Eötvös Loránd University in 1922 with the intention of studying chemistry but soon discovered that her real interest was mathematics. She studied with world-famous mathematicians, including Lipót Fejér and József Kürschák, and it was here that she met a longtime collaborator, László Kalmár, who first called her attention to the subject of recursive functions.

After she graduated in 1927, Péter lived by taking tutoring jobs and high-school teaching. She also began graduate studies. Kalmár told her about Gödel's work on the subject of incompleteness,** whereupon she devised her own, different proofs, focusing on the recursive functions used by Gödel. She gave a paper on the recursive functions at the International Congress of Mathematicians in Zurich in 1932, where she first proposed that such functions be studied as a separate subfield of mathematics. More papers followed, and she received her Ph.D. summa cum laude in 1935. In 1937, she became a contributing editor of the Journal of Symbolic Logic.

Forbidden to teach by the Fascist laws passed in 1939, and briefly confined to the ghetto in Budapest, Péter continued working during the war years. In 1943, she wrote and printed a book, Playing with Infinity, a discussion of ideas in number theory and logic for the lay reader. Many copies were destroyed by bombing and the book was not distributed until the war ended. She lost her brother and many friends and fellow mathematicians to Fascism, and a foreword to later editions of Playing with Infinity‡ memorializes them.

In 1945, the war over, she obtained her first regular position at the Budapest Teachers' College. In 1951 she published a monograph, Recursive Functions, which went through many editions and which earned her the state's Kossuth Award. When the teachers' college was closed in 1955, she became a professor at Eötvös Loránd University, until her retirement in 1975. In 1976, she published Recursive Functions in Computer Theory. She was called Aunt Rózsa by generations of students and worked to increase opportunities in mathematics for girls and young women. She died on the eve of her birthday in 1977. In her eulogy, her student Ferenc Genzwein recalled that she taught "that facts are only good for bursting open the wrappings of the mind and spirit" in the "endless search for truth."§

* "Mathematics is Beautiful," an address delivered to high school teachers and students in 1963 and published in the journal Mathematik in der Schule 2 (1964), pp. 81-90. An English translation by Leon Harkleroad (Cornell University) was published in The Mathematical Intelligencer 12 (1990), pp. 58-64. We are indebted to Leon Harkleroad for permission to quote from published and unpublished materials.
** Related in "Rózsa Péter: Recursive Function Theory's Founding Mother," by Edie Morris (University of Louisville) and Leon Harkleroad, published with Péter's speech in The Mathematical Intelligencer, op. cit.
‡ Translated and published in the United States by Dover in 1976.
§ Translated by Leon Harkleroad, personal communication.