This biography, written by J J O’Connor and E F Robertson, has been republished with permission from the School of Mathematics and Statistics at the University of St Andrews, Scotland.
Born: 4 September 1899, Germany
Died: 1 December 1942
Country most active: Germany
Also known as: NA
Hildegard Ille’s parents were Otto Friedrich Carl Ille and Agnes Clara Bertha Thurm. Otto Ille had been born in Berlin on 3 May 1870 and had become a medical doctor. He married Bertha Thurm on 6 December 1898 in Berlin. Bertha Thurm had been born on 15 August 1875 in Berlin. Their only child Hildegard Ille, the subject of this biography, was born in Bibra on 4 September 1899. Bibra is roughly half way between Leipzig and Frankfurt. Her father, Otto, died in Halle on 30 April 1900 so Hildegard never knew her father.
She attended the Chamisso school in Berlin-Schöneberg, which was named after the famous poet and botanist Adelbert von Chamisso. She graduated from this Realgymnasium, being awarded her Abitur (matriculation examination) in 1918. In the same year that she graduated, she entered the Friedrich-Wilhelms University of Berlin. This famous university had been founded in 1810 and since 1949 has been known as the Humboldt University of Berlin. There she studied mathematics, physics and philosophy. The ordinary professors of mathematics at the University were Friedrich Schottky and Erhard Schmidt, and Issai Schur was an extraordinary professor. In 1920, when Ille was a student at the Friedrich-Wilhelms University of Berlin, she was living at Akazienstrasse 15, Schöneberg, Berlin.
In March 1923 she sat the State Examination to qualify as a secondary school teacher. She was already undertaking research for her doctorate, advised by Issai Schur, and she submitted her thesis Zur Irreduzibilität der Kugelfunktionen (On irreducibility of spherical harmonics) to the University of Berlin. She was awarded a doctorate in 1924. Alexander Soifer writes that, after proving a Ramsey type conjecture:-
… Van der Waerden walked away from Ramseyan prehistory. Issai Schur, on the other hand, continued to produce Ramseyan mathematics, and moreover directed and inspired his PhD students Richard Rado, Hildegard Ille and Alfred Brauer to do the same.
From 1 April 1925, she held a one year scholarship at the Kaiser Wilhelm Institute for Physics, which was founded in 1917 and headed by Albert Einstein until he was forced to emigrate in 1933:-
Now the Kaiser Wilhelm Institute for Physics only existed as an institution – without buildings and employees – but the annual budget was used to award scholarships to young scientists and associates (including female associates).
Unlike some others who were awarded similar scholarships, for Ille the scholarship was her only means of support. Five other scientists received a grant from the Kaiser Wilhelm Institute of Physics in the academic year 1925-26. She was the only woman and, very unusually at this time, she received a higher scholarship than her male counterparts. This decision had been taken by Max von Laue (1879-1960) who, as a deputy of Albert Einstein, had been entrusted with this affairs of the Institute. It is also interesting to see that the physicists at the Kaiser Wilhelm Institute for Physics were looking to collaborate with a mathematician.
After holding the scholarship for a year, Ille began her teacher training as a student teacher at her former school, the Chamisso school in Berlin-Schöneberg. She taught there from 1926 until 1928 when she married Erich Rothe. Erich Rothe had studied at the University of Berlin at the same time as Ille. Although Rothe was four years older, he had served in the military in World War I so was older than the typical student when making his university studies. He took the State Examination to qualify as a secondary school teacher in March 1923, at the same examination diet as Ille. Rothe had worked at the Institute of Applied Mathematics at the University of Berlin in 1926-27 before being appointed to the Engineering School in Breslau in 1927 and habilitating there in 1928. In addition to his position at the Engineering School, he was appointed as a docent at the University of Breslau in 1931 after a second habilitation there. After Erich and Hildegard Rothe married on 20 March 1928, they had a son, Erhard William Rothe, who was born in Breslau on 15 April 1931.
Ille had submitted the paper Einige Bemerkungen zu einem von G Pólya herrührenden Irreduzibilitätskriterium (Some remarks on an originating from G Polya’s irreducibility criterion) on 15 May 1924 and it was published in 1926. After she married, however, by the German laws of the time she was not entitled to undertake paid work. She did not give up mathematics but reviewed 40 papers which had been published between 1926 and 1928, under the name Hildegard Rothe, and reviewed 129 papers which had been published between 1930 and 1937, under the name Hildegard Rothe-Ille. Looking at these reviews, mostly of number theory papers, something struck me [EFR] as remarkable. The papers that ille-Rothe reviewed were written in German, English, French, Italian, Russian and Japanese.
On 30 January 1933 Hitler came to power and on 7 April 1933 clause three of the Civil Service Law provided the means of removing Jewish teachers from the universities, and of course also to remove those of Jewish descent from other roles. All civil servants who were not of Aryan descent (having one grandparent of the Jewish religion made someone non-Aryan) were to be retired, with exemptions for participants in World War I and pre-war officials. Erich Rothe had served in World War I so was exempt but it quickly became clear that the exemption would be ignored. Because of his Jewish background, Erich Rothe was dismissed from his positions in 1935. He eventually managed to escape with his wife and child and they went to Zurich. Wilfred Kaplan writes:-
It was in the spring of 1937 that I first came to know Erich Rothe. I was spending a year in Zurich as a graduate student. I had come to Zurich mainly because of Heinz Hopf, and it was to his friend and former classmate Hopf that Erich Rothe had come as a refugee from Nazi Germany. With him were his wife and child, and all were warmly welcomed by the Hopfs.
In 1937, Erich Rothe travelled to the United States to take up the position of Instructor in Mathematics at William Penn College, Oskaloosa, Iowa. He travelled from Zurich to England, then sailed from Southampton on the ship Georgic, arriving in New York on 18 September 1937. Rothe-Ille and her son Erhard remained in Zurich for a year, then in the summer vacation of 1938, Erich Rothe returned to Europe to meet up with his family and returned with them to the United States. Again they first went to England, sailing from Liverpool to New York on the Scythia, and arrived on 2 September 1938. Details were taken went they arrived in New York: Erich H Rothe (age 44), Hildegard B Rothe (age 38) and Erhard O W Rothe (age 7). Hildegard B Rothe is described as being 5 foot 6 inches tall, having a fair complexion, with dark hair and grey eyes. Her son Erhard O W Rothe is described as being 4 foot 2 inches tall, having a fair complexion, with blond hair and grey eyes.
We obtain a snapshot of the family from the 1940 US Census. Rothe-Ille is a part-time teacher of German at William Penn College, Oskaloosa. She had worked for 36 weeks in 1939 and in the week before the census she had worked for seven hours. She had begun the process of applying for American Citizenship but died before that process could be completed.
Rothe-Ille died from cancer in Mercy Hospital Oskaloosa on 28 October 1942. Her funeral was held on 31 October 1942 when she was buried in the Forest Cemetery, Oskaloosa.
Alexander Soifer relates an interesting connection between Hildegard Rothe-Ille and Paul Erdős:-
In his first-ever open-ended problem paper, Paul Erdős indicates that before him and Turán, Issai Schur called on studying longest arithmetic-progression-free opening segments of positive integers. Erdős writes: “The problem itself seems to be much older (it seems likely that Schur gave it to Hildegard Ille, in the 1920s).” Erdős returns to Issai Schur’s contribution in his 1961 second open-problem paper… : “The problem may be older but I can not definitely trace it. Schur gave it to Hildegard Ille around 1930.” Paul told me that he “met Issai Schur once in mid 1930s,” more precisely in 1936 in Berlin … Undoubtedly, they discussed prime numbers, but likely not arithmetic progressions. Erdős learned about Schur’s interest in arithmetic progressions and early Ramsey-like conjectures and results from Hildegard Ille (1899-1942). Now this requires a bit of explanation, because they probably had never met! … Erich Rothe was Paul Erdős’s source of reliable information on problems and conjectures in number theory that Issai Schur shared with Rothe’s wife Hildegard (Ille) Rothe. From Rothe, Erdős learned about Schur’s authorship of the arithmetic progressions conjecture, proven by Van der Waerden. From Rothe, Erdős learned that Issai Schur yet again contributed to number theory and Ramsey theory when he asked his graduate student Hildegard to investigate arithmetic progression-free arrays of positive integers. … [The] Erdős-Rothe conversations took place after Hildegard’s passing in 1942.
Let us end this article by giving some details of Erhard William Rothe’s career. Born in Breslau, he was seven years old when the family arrived in the United States. At the time of the 1940 Census, he was in the 3rd grade at school in Oskaloosa, Ohio. After secondary education he went to the University Michigan, was awarded a B.Sc. in Chemistry in 1953 and a Ph.D. in Chemistry in 1959. From 1959 he worked for General Dynamics in their Convair Division which manufactured aircraft. After ten years with General Dynamics, he became a Professor of Engineering at Wayne State University, Detroit. He worked at the Max Planck Institute, Göttingen, each summer beginning in 1980 and became a Humboldt-Planck fellow of the Humboldt Foundation, Bonn, in 1990. His:-
… achievements include co-discovery of the merging beams technique of atomic scattering, of the glory effect in molecular collisions, of the electron-hydrogen atom scattering technique, of the three-laser experiment to photodissociate isolated state-selected molecules, and of laser-based diagnostic techniques.