Yu-Chi Ho

Yu-Chi Ho

"This article is about the Chinese-American mathematician."For|the writer and mayor of St Paul|Laurence C. HodgsonInfobox_Scientist
name = Yu-Chi "Larry" Ho

caption =
birth_date = birth date and age|1934|3|1
birth_place = Shanghai, China
death_date =
death_place =
residence = United States
nationality = American (1961-present) Chinese (1934-1961)
field = Applied mathematics
Control theory
work_institution = Harvard University
alma_mater = Harvard University Massachusetts Institute of Technology
doctoral_advisor = Arthur E. Bryson, Jr. Kumpati S. Narendra
awards = Richard E. Bellman Control Heritage Award Rufus Oldenburger Medal IEEE Control System Field Award

Yu-Chi "Larry" Ho ( _zh. 何毓琦) (born March 1, 1934 in Shanghai, China) is a renowned Chinese-American mathematician, control theorist, and a professor at the School of Engineering and Applied Sciences, Harvard University.

He is well-known as the co-author of "Applied Optimal Control", the top referenced work on the subject of optimal control,cite book
author = Bryson, A.E.
coauthors = Ho, Y.C.
year = 1975
title = Applied optimal control
publisher = Washington, DC: Hemisphere
isbn =
] as well as a pioneer in various other fields such as differential games, pattern recognition, and discrete event dynamic systems.



Yu-Chi Ho was born on March 1, 1934 in Shanghai, China and came to the United States at the age of 15 in 1949. After finishing the last year of high school in 1950, Ho was accepted to the Massachusetts Institute of Technology where he received a S.B. in Electrical Engineering in the summer of 1953, at the age of 19. Ho later reported that his initial interests were in mechanical engineering, due to a childhood experience repairing an European ornamental clock without any previous knowledge of its mechanisms. His application to MIT mechanical engineering, however, was routed to the electrical engineering department by mistake, and Ho decided to stay in the department. [ [http://www.sciencenet.cn/blog/user_content.aspx?id=23182 On Research and Education (#11) Changing Research Direction and Field of Endeavor] ] Ho continued his graduate studies at MIT, receiving a S.M. degree in Electrical Engineering in 1955.

After working for Bendix Aviation for three years, Ho moved to Harvard University in 1958 where he completed a Ph.D. in Applied Mathematics in 1961. His thesis "A Study Optimal Control of Dynamic Systems" was advised by Arthur E. Bryson, Jr. and Kumpati S. Narendra.


After finishing his Ph.D. in the spring of 1961, Yu-Chi Ho left for a summer job in California, skipping the graduation ceremony.cite web |url=http://www.sciencenet.cn/blog/user_content.aspx?id=2438 |title=An American Graduation |author=Yu-Chi Ho |date=2007-05-25 |accessdate=2008-05-20] Ho returned to Harvard in the fall of 1961 for a teaching appointment, receiving tenure in 1965, [ [http://www.sciencenet.cn/blog/user_content.aspx?id=7579 Harvard Celebrates the launching of the School of Engineering and Applied Sciences September 20, 2007] ] and remained in the School of Engineering and Applied Sciences until his retirement in 2001. At Harvard, Ho held the title of Gordon McKay Professor of Systems Engineering, Emeritus, as well as the T. Jefferson Coolidge Chair of Applied Mathematics, Emeritus. He was also the visiting professor to the Cockrell Family Regent's Chair in Engineering at the University of Texas, Austin in 1989. In 2001, Ho retired from teaching duties at Harvard after 40 years of service and became a Research Professor. He was appointed (part time) the Chair Professor and Chief Scientist at the Center for Intelligent and Networked Systems (CFINS), Department of Automation, Tsinghua University. In his career, he has supervised 50 Ph.D. students at Harvard and 3 students at Tsinghua.

Ho has an Erdös number of 5: Yu-Chi Ho - Rudolf E. Kalman - Michael A. Arbib - Yehoshafat Giveon - Yechezkel Zalcstein - Paul Erdös

Professional activities

Yu-Chi Ho is a member of the U.S. National Academy of Engineering and a foreign member of the Chinese Academy of Engineering and the Chinese Academy of Sciences. He is also an IEEE Life Fellow and an INFORMS Inaugural Fellow, and a Distinguished Member of the IEEE Control Systems Society. In addition to services on various governmental and industrial panels, and professional society administrative bodies, he was the program chairman for the IEEE Conference on Decision and Control 1972, the general chairman of the IEEE Robotics and Automation Conference 1987, and President of the IEEE Robotics & Automation Society in 1988. Ho co-founded Network Dynamics, Inc., a software firm specializing in industrial automation. He is on the editorial boards of several international journals and is the founding editor-in-chief of the international Journal on Discrete Event Dynamic Systems.

Community service

Yu-Chi Ho was the founder and the first chair of the annual United Asian American Dinner of Massachusetts. He also served as the Chairman of the Board of Greater Boston Chinese Cultural Association from 1995 to 1998, the President of the New England Chapter of the Organization of Chinese Americans from 1982 to 1985, a board member of the Mass Endowment for Humanities from 1985 to 1989, and a founding member and member of the steering committee of the 80-20 Initiative, a national political movement for Asian Americans.

Honors and Awards

* Guggenheim Fellowship (1970)
* IEEE Field Award for Control Engineering and Science (1989)
* Chiang Technology Achievement Award (1993)
* American Automatic Control Council Richard E. Bellman Control Heritage Award (1999)
* American Society of Mechanical Engineers Rufus Oldenburger Medal (1999)
* Isaacs Award from the International Society of Dynamic Games (2004)

Personal life

Ho became a naturalized citizen of the United States in 1961. He proposed to his wife Sophia on Valentine's Day, 1959, [cite web |url=http://www.sciencenet.cn/blog/user_content.aspx?id=15663 |title=A Valentine Day Tribute to My Wife |author=Yu-Chi Ho |date=2008-02-12 |accessdate=2008-05-20] and they have three children, Adrian, Christine and Lara, born in 1961, 1963, and 1973, [ [http://www.sciencenet.cn/blog/user_content.aspx?id=15214 The Family Automobile Trip and vacation in the US] ] two of which received Ph.D. degrees. They currently reside in Lexington, Massachusetts. Since April 25, 2007, Ho blogs on ScienceNet.cn, a science blog network sponsored by the Chinese Academy of Engineering and the Academy of Sciences. [http://www.sciencenet.cn/blog/何毓琦.htm]


Control theory and optimization

Yu-Chi Ho's research in control theory began when he was a graduate student at MIT. His first paper published in 1955, titled "time-domain compensation for closed-loop systems by a delay line method", presented a new approach to the synthesis and analysis of closed-loop systems in the time domain.cite journal
author = Ho, Y.C.
year = 1955
title = Time-domain compensation for closed-loop systems by a delay line method
url = http://dspace.mit.edu/handle/1721.1/4793
accessdate = 2008-05-11
] Following his meeting with Rudolf E. Kalman at the first American Control Conference in 1960, [ [http://www.sciencenet.cn/blog/user_content.aspx?id=11577 On Research #10 - some specific advice to Chinese Ph.D students] ] Ho collaborated early with Kalman who started what is now known as the modern control theory. The widely used classical control theory at the time focused on analysis in the frequency domain using Laplace and Fourier transforms, and the techniques proposed by Kalman, the time-domain based state space models, were not widely accepted. With Kalman, Ho showed that the state space representation provides a convenient and compact way to model and analyze dynamical systems with multiple inputs and outputs which would otherwise take multiple Laplace transforms to encode, and it can be extended into nonlinear systems. Seminar papers in area includes "controllability of linear dynamic systems",cite journal
author = Kalman, R.E.
coauthors = Ho, Y.C.; Narendra, K.S.
year = 1963
title = Controllability of linear dynamical systems
journal = Contributions to Differential Equations
volume = 1
issue = 2
pages = 189-213

] an in-depth investigation of the theory of controllability proposed by Kalman in 1961 (then known as the Kalman-Bertram condition).

Together with his student Robert Lee at MIT, the paper "A Bayesian approach to problems in stochastic estimation and control" formulated a general class of stochastic estimation and control problems from a Bayesian Decision-Theoretic viewpoint.cite journal
author = Ho, Y.
coauthors = Lee, R.
year = 1964
title = A Bayesian approach to problems in stochastic estimation and control
journal = Automatic Control, IEEE Transactions on
volume = 9
issue = 4
pages = 333-339
url = http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1105763
accessdate = 2008-05-19

Pattern recognition

After joining the faculty of Harvard University, Ho developed the Ho-Kashyap rule in pattern recognition with his first Ph.D. student, Rangasami L. Kashyap.cite journal
author = Ho, Y.C.
coauthors = Kashyap, R.L.
year = 1965
title = An algorithm for linear inequalities and its applications
journal = IEEE Trans. Elec. Comp
volume = 14
issue = 5
pages = 683-688
url = http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4038552
accessdate = 2008-05-11

doi = 10.1109/PGEC.1965.264206
format = abstract
] cite journal
author = Ho, Y.C.
coauthors = Kashyap, R.L.
year = 1966
title = A Class of Iterative Procedures for Linear Inequalities
journal = SIAM Journal on Control
volume = 4
pages = 112
url = http://link.aip.org/link/?SJCODC/4/112/1
accessdate = 2008-05-19

Game theory

He then turned his attention to game theory, and published in 1965 the landmark paper "Differential Games and Optimal Pursuit-Evation Strategies",cite journal
author = Ho, Y.
coauthors = Bryson, A.; Baron, S.
year = 1965
title = Differential games and optimal pursuit-evasion strategies
journal = Automatic Control, IEEE Transactions on
volume = 10
issue = 4
pages = 385-389
url = http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1098197
accessdate = 2008-05-11

doi = 10.1109/TAC.1965.1098197
format = abstract
] proving the optimality of a proportional guidance scheme. His paper "Nonzero Sum Differential Games"cite journal
author = Starr, A.W.
coauthors = Ho, Y.C.
year = 1969
title = Nonzero-sum differential games
journal = Journal of Optimization Theory and Applications
volume = 3
issue = 3
pages = 184-206
url = http://www.springerlink.com/index/U1866221K3862601.pdf
accessdate = 2008-05-11

doi = 10.1007/BF00929443 ] opened the way for general game-theoretic studies in systems and control.

Discrete event dynamic systems

Since the 1970s, Ho focused on research in discrete event dynamic systems, making significant contributions in perturbation analysis and ordinal optimization, including the book "Perturbation Analysis of Discrete Event Dynamic Systems", a primary reference in perturbation analysis.cite journal
author = Ho, Y.C.
coauthors = Cao, X.R.
year = 1991
title = Discrete Event Dynamic Systems and Perturbation Analysis
journal = Kiuwer Aca-demic Publishers, Boston



* cite book
author = Bryson, A.E.
coauthors = Ho, Y.C.
year = 1975
title = Applied optimal control
publisher = Washington, DC: Hemisphere
isbn = 0891162283

* cite book
author = Ho, Y.C.
coauthors = Cao, X.R.
year = 1991
title = Discrete Event Dynamic Systems and Perturbation Analysis
publisher = Kiuwer Aca-demic Publishers, Boston
isbn = 0891162283

* cite book
author = Ho, Y.C.
coauthors = Zhao, Q.C, Jia, Q.S.
title = Ordinal Optimization: Soft Optimization for Hard Problems
publisher = Springer
location = Berlin
year = 2007
isbn = 0387372326

About Yu-Chi Ho's work

* cite journal
author = Gong, W.B.
coauthors = Yao, D.D.
year = 1999
title = An Appreciation of Professor Yu-Chi Ho
journal = Journal of Optimization Theory and Applications
volume = 100
issue = 3
pages = 453-456
url = http://www.springerlink.com/index/H06X87543U783265.pdf
accessdate = 2008-05-11

doi = 10.1023/A:1022674003827


External links

* [http://people.seas.harvard.edu/~ho/ Home Page at Harvard University]
* [http://genealogy.math.ndsu.nodak.edu/id.php?id=18753 Mathematics Genealogy Project profile]
*en [http://www.sciencenet.cn/blog/何毓琦.htm Sciencenet.cn Blog]
* [http://www.asianamerican.net/bios/Ho-Larry.html Who's Who of Asian Americans biography]

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