Ronald Getoor
{{Short description|American mathematician}}
{{Infobox scientist
| name = Ronald Kay Getoor
| birth_name = Ronald Kay Getoor
| image = Getoor.jpg
| caption = Ronald Getoor, Oberwolfach 1984
| birth_date = {{birth date|df=y|1929|02|09}}
| birth_place = Royal Oak, Michigan
| death_date = {{death date and age|2017|10|28|1929|02|09}}
| other_names =
| nationality = United States
| fields = Probability
| workplaces = {{Plainlist|
}}
| alma_mater = University of Michigan
| thesis_title = Some Connections Between Operators in Hilbert Space and Random Functions of Second Order
| thesis_year = 1954
| doctoral_advisor = Arthur Herbert Copeland
| doctoral_students = {{Plainlist|
- Philip Protter
- Henryk Gzyl
}}
| notable_students =
| known_for = Blumenthal-Getoor index
| influences =
| influenced =
| awards =
| signature =
| signature_alt =
| website =
| footnotes =
}}
Ronald Kay Getoor (9 February 1929, Royal Oak, Michigan – 28 October 2017, La Jolla, San Diego, California){{r|Gale}}{{r|SDUnionTribune}} was an American mathematician.
Getoor received from the University of Michigan bachelor's degree in 1950, master's degree in 1951,{{r|UCSanDiegoprofile}} and Ph.D. in 1954 under Arthur Herbert Copeland with thesis Connections between operators in Hilbert space and random functions of second order.{{MathGenealogy|id=5112}} As a postdoc he was an instructor at Princeton University. He became in 1956 an assistant professor and then full professor at the University of Washington. During the academic year 1964–1965 he was a visiting professor at Stanford University. From 1966 until his retirement in 2000 he was a professor at the University of California, San Diego.
Getoor's research deals with probability theory, especially the theory of Markov processes and potential theory. In 1970 he was an invited speaker at the International Congress of Mathematicians in Nice. He was elected a Fellow of the Institute of Mathematical Statistics and in 2012 a Fellow of the American Mathematical Society.
Scientific work
In the late 1950s, Getoor and Robert Blumenthal set out to understand the work of Gilbert Hunt on the connection between Markov processes and potential theory, extending the connections between Brownian motion and Newtonian potential theory.
Getoor's book on 'Markov processes and potential theory', co-authored with Blumenthal, became a reference on the topic.
Together with Blumenthal and Sharpe, Getoor obtained many results on the fine structure of Markov processes and martingales, in particular the theory of local time for Markov processes.
With Michael J. Sharpe, Getoor defined the notion of 'conformal martingale', {{Cite journal | doi = 10.1007/BF01425714| title = Conformal martingales| journal = Inventiones Mathematicae| volume = 16| pages = 271–308| year = 1972| last1 = Getoor | first1 = R.K.| last2 = Sharpe | first2 = M.J.| issue = 4| bibcode = 1972InMat..16..271G| s2cid = 189830360}} which proved to be influential in potential theory, investigated the behavior of Bessel processes, last-exit times and excursions. Starting in the early 1980s, Getoor studied stationary extensions of a given strong Markov process, with time extending to infinity in both directions, formulating a pathwise view of "time reversal" which became a key tool in his studies of the excessive measures of a Markov process.
The 'Blumenthal-Getoor index', a concept which characterises the nature of discontinuities of Lévy processes and semi-martingales, is named after him.
Personal life
He married in 1959. His wife Ann Getoor worked on the design of commercial aircraft at Boeing, and his daughter Lise Getoor is a professor of computer science at the University of California, Santa Cruz. Getoor died at home on October 28, 2017, in La Jolla at the age of 88.
Selected publications
;Books
- {{cite book|title=Markov processes: Ray processes and right processes|publisher=Springer Verlag|series=Lecture Notes in Mathematics 440|year=1975}} {{cite book|title=2006 reprint|isbn=9783540374220|postscript=; pbk, 124 pages|url=https://books.google.com/books?id=GV17CwAAQBAJ|last1=Getoor|first1=R. K.|date=15 November 2006|publisher=Springer }}
- with Robert McCallum Blumenthal: {{cite book|title=Markov Processes and Potential Theory|publisher=Academic Press|year=1968}}{{cite journal|author=Meyer, P. A.|authorlink=Paul-André Meyer|title=Review: Markov processes and potential theory by R. M. Blumenthal and R. K. Getoor|journal=Bull. Amer. Math. Soc.|year=1969|volume=75|issue=5|pages=912–916|url=http://www.ams.org/journals/bull/1969-75-05/S0002-9904-1969-12282-2/S0002-9904-1969-12282-2.pdf|doi=10.1090/s0002-9904-1969-12282-2|doi-access=free}}
- {{cite book|title=Excessive Measures|publisher=Birkhäuser|year=1990}} {{cite book|title=2012 reprint|isbn=9781461234708|postscript=; pbk, 190 pages|url=https://books.google.com/books?id=UxvSBwAAQBAJ|last1=Getoor|first1=R. K.|date=6 December 2012|publisher=Springer }}
;Articles
- {{cite journal|title=Some theorems on stable processes|journal=Trans. Amer. Math. Soc.|volume=95|issue=2|year=1960|pages=263–273|doi=10.1090/S0002-9947-1960-0119247-6|last1=Blumenthal|first1=R. M.|last2=Getoor|first2=R. K.|doi-access=free}}
- {{cite journal|title=Sample functions of stochastic processes with stationary independent increments|journal=Journal of Mathematics and Mechanics|volume=10|issue=3|year=1961|pages=493–516|jstor=24900735|last1=Blumenthal|first1=R. M.|last2=Getoor|first2=R. K.}}
- {{cite journal|title=On the distribution of first hits for the symmetric stable processes|journal= Trans. Amer. Math. Soc.|volume=99|issue= 3|year=1961|pages=540–554|doi=10.1090/S0002-9947-1961-0126885-4|last1= Blumenthal|first1= R. M.|last2= Getoor|first2= R. K.|last3= Ray|first3= D. B.|doi-access= free}}
- {{cite journal|title=Additive functionals of Markov processes in duality|journal=Trans. Amer. Math. Soc.|volume=112|year=1964|pages=131–163|doi=10.1090/S0002-9947-1964-0160269-0|last1=Blumenthal|first1=R. M.|last2=Getoor|first2=R. K.|doi-access=free}}
- {{cite journal|title=Local times for Markov processes|journal=Zeitschrift für Wahrscheinlichkeitstheorie und Verwandte Gebiete|volume=3|issue=1|year=1964|pages=50–74|doi=10.1007/BF00531683|last1=Blumenthal|first1=R. M.|last2=Getoor|first2=R. K.|s2cid=120071327}}
- {{Cite journal | doi = 10.1007/BF01425714| title = Conformal martingales| journal = Inventiones Mathematicae| volume = 16| pages = 271–308| year = 1972| last1 = Getoor | first1 = R. K.| last2 = Sharpe | first2 = M. J.| issue = 4| bibcode = 1972InMat..16..271G| s2cid = 189830360}}
References
External links
- [http://www.rohshalloffame.com/graduates/getoor-ronald-k.html Getoor, Ronald K., Royal Oak High School Hall of Fame]
- [https://web.archive.org/web/20151001055432/http://celebratio.org/Getoor_RK/article/127/ Complete bibliography]
{{Authority control}}
{{DEFAULTSORT:Getoor, Ronald}}
Category:American probability theorists
Category:University of Michigan alumni
Category:University of Washington faculty
Category:University of California, San Diego faculty
Category:Fellows of the Institute of Mathematical Statistics