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Tom Brown (mathematician)

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American-Canadian mathematician
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Tom Brown
BornThomas Craig Brown
1938 (age 86–87)
Portland, Oregon, U.S.
Alma mater
Known for
  • Brown's Lemma
Scientific career
Fields
InstitutionsSimon Fraser University
Thesis On Semigroups which are Unions of Periodic Groups  (1964)
Doctoral advisorEarl Edwin Lazerson

Thomas Craig Brown (born 1938) is an American-Canadian mathematician, Ramsey Theorist, and Professor Emeritus at Simon Fraser University.

Collaborations

As a mathematician, Brown’s primary focus in his research is in the field of Ramsey Theory. When completing his Ph.D., his thesis was 'On Semigroups which are Unions of Periodic Groups' In 1963 as a graduate student, he showed that if the positive integers are finitely colored, then some color class is piece-wise syndetic.

In A Density Version of a Geometric Ramsey Theorem, he and Joe P. Buhler showed that “for every ε > 0 {\displaystyle \varepsilon >0} there is an n ( ε ) {\displaystyle n(\varepsilon )} such that if n = d i m ( V ) n ( ε ) {\displaystyle n=dim(V)\geq n(\varepsilon )} then any subset of V {\displaystyle V} with more than ε | V | {\displaystyle \varepsilon |V|} elements must contain 3 collinear points” where V {\displaystyle V} is an n {\displaystyle n} -dimensional affine space over the field with p d {\displaystyle p^{d}} elements, and p 2 {\displaystyle p\neq 2} ".

In Descriptions of the characteristic sequence of an irrational, Brown discusses the following idea: Let α {\displaystyle \alpha } be a positive irrational real number. The characteristic sequence of α {\displaystyle \alpha } is f ( α ) = f 1 f 2 {\displaystyle f(\alpha )=f_{1}f_{2}\ldots } ; where f n = [ ( n + 1 ) α ] [ α ] {\displaystyle f_{n}=} .” From here he discusses “the various descriptions of the characteristic sequence of α which have appeared in the literature” and refines this description to “obtain a very simple derivation of an arithmetic expression for [ n α ] {\displaystyle } .” He then gives some conclusions regarding the conditions for [ n α ] {\displaystyle } which are equivalent to f n = 1 {\displaystyle f_{n}=1} .

He has collaborated with Paul Erdős, including Quasi-Progressions and Descending Waves and Quantitative Forms of a Theorem of Hilbert.

References

  1. "Tom Brown Professor Emeritus at SFU". Retrieved 10 November 2020.
  2. Jensen, Gary R.; Krantz, Steven G. (2006). 150 Years of Mathematics at Washington University in St. Louis. American Mathematical Society. p. 15. ISBN 978-0-8218-3603-3.
  3. Brown, T. C. (1971). "An interesting combinatorial method in the theory of locally finite semigroups" (PDF). Pacific Journal of Mathematics. 36 (2): 285–289. doi:10.2140/pjm.1971.36.285.
  4. Brown, T. C.; Buhler, J. P. (1982). "A Density version of a Geometric Ramsey Theorem" (PDF). Journal of Combinatorial Theory. Series A. 32: 20–34. doi:10.1016/0097-3165(82)90062-0.
  5. Brown, T. C. (1993). "Descriptions of the Characteristic Sequence of an Irrational" (PDF). Canadian Mathematical Bulletin. 36: 15–21. doi:10.4153/CMB-1993-003-6.
  6. Brown, T. C.; Erdős, P.; Freedman, A. R. (1990). "Quasi-Progressions and Descending Waves". Journal of Combinatorial Theory. Series A. 53: 81–95. doi:10.1016/0097-3165(90)90021-N.
  7. Brown, T. C.; Chung, F. R. K.; Erdős, P. (1985). "Quantitative Forms of a Theorem of Hilbert" (PDF). Journal of Combinatorial Theory. Series A. 38 (2): 210–216. doi:10.1016/0097-3165(85)90071-8.

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