Hale Trotter

Hale Freeman Trotter (30 May 1931 – 17 January 2022)[1][2] was a Canadian-American mathematician, known for the Lie–Trotter product formula,[3] the Steinhaus–Johnson–Trotter algorithm, and the Lang–Trotter conjecture. He was born in Kingston, Ontario.[1] He died in Princeton, New Jersey on January 17, 2022.

Hale Trotter
Trotter in 1978
Born(1931-05-30)30 May 1931
Kingston, Ontario, Canada
Died17 January 2022(2022-01-17) (aged 90)
Princeton, New Jersey, United States
NationalityAmerican
Alma materQueen's University at Kingston
Princeton University
Known forLie–Trotter product formula
Steinhaus–Johnson–Trotter algorithm
Lang–Trotter conjecture
Scientific career
FieldsMathematics
InstitutionsPrinceton University
Doctoral advisorWilliam Feller

Biography

The son of historian Reginald George Trotter, Hale Trotter studied at Queen's University in Kingston with bachelor's degree in 1952 and master's degree in 1953. He received in 1956 his PhD from Princeton University under William Feller with thesis Convergence of semigroups of operators.[4] Trotter was from 1956 to 1958 at Princeton University the Fine Instructor for mathematics and from 1958 to 1960 an assistant professor at Queen's University. He was from 1962 to 1963 a visiting associate professor, from 1963 to 1969 an associate professor, and from 1969 until his retirement a full professor at Princeton University. From 1962 to 1986 he was an associate director for Princeton University's data center.

Trotter's research dealt with, among other topics, probability theory, group theory computations, number theory, and knot theory. In 1963, he solved an open problem in knot theory by proving that there are non-invertible knots.[5] At the time of his proof, all knots with up to 7 crossings were known to be invertible. Trotter described an infinite number of pretzel knots that are not invertible.

Selected publications

Articles

Books
  • Williamson, Richard E.; Crowell, Richard H.; Trotter, Hale F. (1972). Calculus of vector functions (Second ed.). Prentice-Hall.
  • Lang, Serge; Trotter, Hale Freeman (1976). Frobenius distributions in GL2-extensions: distribution of Frobenius automorphisms in GL2-extensions of the rational numbers. Lecture Notes in Mathematics. Vol. 504. Springer Verlag. doi:10.1007/BFb0082087.
  • Williamson, Richard E.; Trotter, Hale F. (1995). Multivariable Mathematics. Prentice-Hall.

References
  1. biographical information from American Men and Women of Science, Thomson Gale 2004
  2. "In Memory of Hale Freeman Trotter". Mather-Hodge Funeral Home. Retrieved 2022-02-08.
  3. Trotter, H. F. (1959). "On the product of semi-groups of operators". Proceedings of the American Mathematical Society. 10 (4): 545–551. doi:10.2307/2033649. ISSN 0002-9939. JSTOR 2033649. MR 0108732.
  4. Hale Trotter at the Mathematics Genealogy Project
  5. Trotter, H. F. (1963). "Non-invertible knots exist". Topology. 2 (4): 275–280. doi:10.1016/0040-9383(63)90011-9.
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