Gisbert Hasenjaeger

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Autumn 1949 in Oberwolfach (4th from left)

Gisbert Hasenjaeger (born June 1, 1919 in Hildesheim ; † September 2, 2006 ) was a German mathematical logician.

life and work

Hasenjaeger graduated from high school in Mülheim an der Ruhr in 1937 , where his father Edwin Renatus Hasenjaeger , an administrative lawyer, was temporarily mayor. Hasenjaeger was then in the Reich Labor Service and did his military service . During the Second World War he was seriously wounded in January 1942 in the Russian campaign , which he participated in with the artillery. After that he was on assignment by Heinrich Scholz in Section IV a of the encryption department of the High Command of the Wehrmacht under Karl Stein , responsible for the security of the Enigma , but the security holes used by the British for deciphering escaped the agency. From the end of 1945 he studied mathematics and especially mathematical logic with Heinrich Scholz at the Westfälische Wilhelms-Universität in Münster , where he received his doctorate in 1950 ( topological investigations on the semantics and syntax of an extended predicate calculus ) and habilitated in 1953. He knew Scholz from his school days and corresponded with him when he was drafted into the war. In Münster he became his assistant. With Scholz he wrote on his textbook Basic Features of Mathematical Logic in Springer's basic teaching series, which he published in 1961 after his death.

Another close and apparently also lifelong relationship connected Hasenjaeger with Paul Bernays, in which, beginning with the winter semester 1950/51, he spent three semesters at ETH Zurich with funds from the ETH Board with Bernays' set theory and in particular the preparation of a second edition of Hilbert-Bernays' "Fundamentals of Mathematics".

In 1962, Hasenjaeger became a professor at the University of Bonn , where he was director of the newly created seminar for logic and basic research. 1964/65 he was visiting professor at Princeton University . In 1984 he retired, but held lectures for another ten years.

In 1949, independently and simultaneously with Leon Henkin , he developed a new proof of Kurt Gödel's completeness theorem for predicate logic.

Hasenjaeger also dealt with philosophical questions.

As a counterpoint, he developed and built simple logistical machines, especially models for Turing machines, together with Dieter Rödding , who was inspired by the concept of the register machine .

Ronald Jensen and Dieter Rödding are among his doctoral students .

Fonts

  • Introduction to the basic concepts and problems of modern logic. Alber, Freiburg, Munich 1962 (English translation: Introduction to the basic concepts and problems of modern logic, Reidel 1972).
  • with Heinrich Scholz: Fundamentals of mathematical logic. Springer 1961.

literature

Web links

Individual evidence

  1. ↑ Claus-Peter Wirth, A Most Interesting, but Revoked Draft for Hilbert and Bernays' "Basics of Mathematics" that never found its way into any publication, and 2 CV of Gisbert Hasenjaeger , On the question of whether a Reichsarbeitsdienst be voluntary at this time and for the source of this rumor see footnote 20 on p. 27f.
  2. ↑ Friedrich Bauer: Deciphered Secrets , Springer 2000. The office was understaffed with only four employees and Hasenjaeger himself was completely inexperienced as a cryptologist at the time. At least he managed to decipher some Enigma messages in a simplified version right from the start. An inherent weakness of the Enigma, discovered in 1942 by Gordon Welchman for the deciphering work in Bletchley Park, escaped even Alan Turing at the time .
  3. ↑ Gisbert Hasenjäger in the Mathematics Genealogy Project (English)Template: MathGenealogyProject / Maintenance / name used
  4. ↑ Claus-Peter Wirth, A Most Interesting, but Revoked Draft for Hilbert and Bernays' "Fundamentals of Mathematics" that never found its way into any publication, and 2 CV of Gisbert Hasenjaeger , on the collaboration between Hasenjaeger and Bernays, see Section 4 " Hasenjaeger and Bernays ", p. 21ff. and the Appendix, pages 26-44
  5. ↑ Gisbert Hasenjaeger: Logic and Ontology. Studium Generale 19 (3), (1966), 136-140.
  6. ^ Gisbert Hasenjaeger: On the Early History of Register Machines. in: Computation Theory and Logic, In Memory of Dieter Rödding; Egon Börger (ed.), Lecture Notes in Computer Science 270, 181–188 Springer 1987
personal data
SURNAME Hasenjaeger, Gisbert
BRIEF DESCRIPTION German mathematical logician
DATE OF BIRTH June 1, 1919
PLACE OF BIRTH Hildesheim
DATE OF DEATH September 2, 2006