Yu-Chi Ho
Encyclopedia
This article is about the Chinese-American mathematician.
Yu-Chi "Larry" Ho (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 the co-author of Applied Optimal Control, and an influential researcher in differential game
s, pattern recognition
, and discrete event dynamic system
s.
and came to the U.S. where he received a B.S. 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 a 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. Ho continued his graduate studies at MIT, receiving a M.S. 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
.
. In his career, he has supervised 50 Ph.D. students at Harvard and 3 students at Tsinghua.
Ho has an Erdős number
of 4: Yu-Chi Ho - Demosthenis Teneketzis - Wayne Stark - Robert McEliece
- Paul Erdős
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.
. 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.
. Ho collaborated with Rudolf E. Kalman, a pioneer of modern control theory. Before Kalman, time series analysis and classical control theory studied the frequency domain
, using harmonic analysis
, especially Laplace and Fourier transform
s. Kalman developed the study of the time domain
using state-space models
. Joining 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; further, the state-space representation can be extended into nonlinear systems. Their paper controllability of linear dynamic systems, developed the theory of controllability
(then known as the "Kalman-Bertram condition").
Together with Ho's 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.
with his first Ph.D. student, Rangasami L. Kashyap
.
, Ho in 1965 published the paper Differential Games and Optimal Pursuit-Evasion Strategies, that proved the optimality of a proportional guidance scheme. His paper Nonzero Sum Differential Games was an influential game-theoretic study in systems and control, following earlier work by Samuel Karlin
, for example.
s, making contributions in perturbation analysis and ordinal optimization
, including the book Perturbation Analysis of Discrete Event Dynamic Systems.
Yu-Chi "Larry" Ho (born March 1, 1934 in Shanghai, China) is a renowned Chinese-American mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
, control theorist, and a professor
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
at the School of Engineering and Applied Sciences
Harvard School of Engineering and Applied Sciences
The Harvard School of Engineering and Applied Science , a school within Harvard University's Faculty of Arts and Sciences , serves as the connector and integrator of Harvard's teaching and research efforts in engineering, applied sciences, and technology.Engineering and applied sciences at Harvard...
, Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
.
He is the co-author of Applied Optimal Control, and an influential researcher in differential game
Differential game
In game theory, differential games are a group of problems related to the modeling and analysis of conflict in the context of a dynamical system. The problem usually consists of two actors, a pursuer and an evader, with conflicting goals...
s, pattern recognition
Pattern recognition
In machine learning, pattern recognition is the assignment of some sort of output value to a given input value , according to some specific algorithm. An example of pattern recognition is classification, which attempts to assign each input value to one of a given set of classes...
, and discrete event dynamic system
Discrete event dynamic system
In control engineering, a discrete event dynamic system is a discrete-state, event-driven system of which the state evolution depends entirely on the occurrence of asynchronous discrete events over time...
s.
Education
Yu-Chi Ho was born on March 1, 1934 in Shanghai, China and left home at the age of 15 in 1949 to complete his high school education in Hongkong. In 1950, Ho was accepted to the Massachusetts Institute of TechnologyMassachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
and came to the U.S. where he received a B.S. in Electrical Engineering
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...
in the summer of 1953, at the age of 19. Ho later reported that his initial interests were in mechanical engineering
Mechanical engineering
Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the...
, due to a childhood experience repairing a 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. Ho continued his graduate studies at MIT, receiving a M.S. degree in Electrical Engineering
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...
in 1955.
After working for Bendix Aviation
Bendix Aviation
The Bendix Aviation Corporation, a manufacturer of aircraft parts, was started by inventor Vincent Bendix in 1929 as a continuation of his auto parts company. It was renamed to Bendix Corporation in 1960, and in 1983 was acquired by the Allied Corporation and combined with King Radio company to...
for three years, Ho moved to Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
in 1958 where he completed a Ph.D.
Ph.D.
A Ph.D. is a Doctor of Philosophy, an academic degree.Ph.D. may also refer to:* Ph.D. , a 1980s British group*Piled Higher and Deeper, a web comic strip*PhD: Phantasy Degree, a Korean comic series* PhD Docbook renderer, an XML renderer...
in Applied Mathematics
Applied mathematics
Applied mathematics is a branch of mathematics that concerns itself with mathematical methods that are typically used in science, engineering, business, and industry. Thus, "applied mathematics" is a mathematical science with specialized knowledge...
in 1961. His thesis A Study Optimal Control of Dynamic Systems was advised by Arthur E. Bryson, Jr. and Kumpati S. Narendra
Kumpati S. Narendra
Kumpati S. Narendra is an American control theorist, who currently holds the Harold W. Cheel Professorship of Electrical Engineering at Yale University. He received the Richard E. Bellman Control Heritage Award in 2003. He is noted "for pioneering contributions to stability theory, adaptive and...
.
Career
After finishing his Ph.D. in the spring of 1961, Yu-Chi Ho returned to Harvard in the fall of 1961 for a teaching appointment, receiving tenure in 1965, 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 UniversityTsinghua University
Tsinghua University , colloquially known in Chinese as Qinghua, is a university in Beijing, China. The school is one of the nine universities of the C9 League. It was established in 1911 under the name "Tsinghua Xuetang" or "Tsinghua College" and was renamed the "Tsinghua School" one year later...
. In his career, he has supervised 50 Ph.D. students at Harvard and 3 students at Tsinghua.
Ho has an Erdős number
Erdos number
The Erdős number describes the "collaborative distance" between a person and mathematician Paul Erdős, as measured by authorship of mathematical papers.The same principle has been proposed for other eminent persons in other fields.- Overview :...
of 4: Yu-Chi Ho - Demosthenis Teneketzis - Wayne Stark - Robert McEliece
Robert McEliece
Robert J. McEliece is a mathematician and engineering professor at the California Institute of Technology best known for his work in information theory. He was the 2004 recipient of the Claude E. Shannon Award and the 2009 recipient of the IEEE Alexander Graham Bell Medal.Educated at Caltech...
- Paul Erdős
Paul Erdos
Paul Erdős was a Hungarian mathematician. Erdős published more papers than any other mathematician in history, working with hundreds of collaborators. He worked on problems in combinatorics, graph theory, number theory, classical analysis, approximation theory, set theory, and probability theory...
Professional activities
Yu-Chi Ho is a member of the U.S. National Academy of EngineeringNational Academy of Engineering
The National Academy of Engineering is a government-created non-profit institution in the United States, that was founded in 1964 under the same congressional act that led to the founding of the National Academy of Sciences...
and a foreign member of the Chinese Academy of Engineering
Chinese Academy of Engineering
The Chinese Academy of Engineering is the national academy of the People's Republic of China for engineering. It was established in 1994 and is an institution of the State Council of China...
and the Chinese Academy of Sciences
Chinese Academy of Sciences
The Chinese Academy of Sciences , formerly known as Academia Sinica, is the national academy for the natural sciences of the People's Republic of China. It is an institution of the State Council of China. It is headquartered in Beijing, with institutes all over the People's Republic of China...
. 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 FellowshipGuggenheim FellowshipGuggenheim Fellowships are American grants that have been awarded annually since 1925 by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the arts." Each year, the foundation makes...
(1970) - IEEE Control Systems Science and Engineering Award (1989)
- Chiang Technology Achievement Award (1993)
- Richard E. Bellman Control Heritage AwardRichard E. Bellman Control Heritage AwardThe Richard E. Bellman Control Heritage Award is an annual award given by the American Automatic Control Council for achievements in control theory, named after the applied mathematician Richard E. Bellman...
from the American Automatic Control CouncilAmerican Automatic Control CouncilThe American Automatic Control Council is an organization founded in 1956 for research in control theory. It is an association of the control systems divisions of eight member societies and a member of the International Federation of Automatic Control....
(1999) - Rufus Oldenburger MedalRufus Oldenburger MedalThe Rufus Oldenburger Medal is an award given by the American Society of Mechanical Engineers recognizing significant contributions and outstanding achievements in the field of automatic control. It was established in 1968 in the honor of Rufus Oldenburger....
from the American Society of Mechanical EngineersAmerican Society of Mechanical EngineersThe American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering....
(1999) - Isaacs Award from the International Society of Dynamic GamesInternational Society of Dynamic GamesThe International Society of Dynamic Games is a is an international non-profit, professional organization for the advancement of the theory of dynamic games...
(2004)
Personal life
Ho became a naturalized citizen of the United States in 1961. He and his wife Sophia have three children. They currently reside in Lexington, MassachusettsLexington, Massachusetts
Lexington is a town in Middlesex County, Massachusetts, United States. The population was 31,399 at the 2010 census. This town is famous for being the site of the first shot of the American Revolution, in the Battle of Lexington on April 19, 1775.- History :...
. Since April 25, 2007, Ho blogs on ScienceNet.cn
ScienceNet.cn
ScienceNet.cn is a science virtual community and science blog. It is launched by Science Times Media Group and supported by Chinese Academy of Sciences, Chinese Academy of Engineering and National Natural Science Foundation of China with the mission of establishing global Chinese science community...
, a science blog network sponsored by the Chinese Academy of Engineering and the Academy of Sciences.
Control theory and optimization
Yu-Chi Ho's research in control theory began when he was a graduate student at MIT. His 1955 paper 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 domainTime domain
Time domain is a term used to describe the analysis of mathematical functions, physical signals or time series of economic or environmental data, with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the case of continuous time, or at various...
. Ho collaborated with Rudolf E. Kalman, a pioneer of modern control theory. Before Kalman, time series analysis and classical control theory studied the frequency domain
Frequency domain
In electronics, control systems engineering, and statistics, frequency domain is a term used to describe the domain for analysis of mathematical functions or signals with respect to frequency, rather than time....
, using harmonic analysis
Harmonic analysis
Harmonic analysis is the branch of mathematics that studies the representation of functions or signals as the superposition of basic waves. It investigates and generalizes the notions of Fourier series and Fourier transforms...
, especially Laplace and Fourier transform
Fourier transform
In mathematics, Fourier analysis is a subject area which grew from the study of Fourier series. The subject began with the study of the way general functions may be represented by sums of simpler trigonometric functions...
s. Kalman developed the study of the time domain
Time domain
Time domain is a term used to describe the analysis of mathematical functions, physical signals or time series of economic or environmental data, with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the case of continuous time, or at various...
using state-space models
State space (controls)
In control engineering, a state space representation is a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations...
. Joining 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; further, the state-space representation can be extended into nonlinear systems. Their paper controllability of linear dynamic systems, developed the theory of controllability
Controllability
Controllability is an important property of a control system, and the controllability property plays a crucial role in many control problems, such as stabilization of unstable systems by feedback, or optimal control....
(then known as the "Kalman-Bertram condition").
Together with Ho's 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.
Pattern recognition
After joining the faculty of Harvard University, Ho developed the Ho-Kashyap rule in pattern recognitionPattern recognition
In machine learning, pattern recognition is the assignment of some sort of output value to a given input value , according to some specific algorithm. An example of pattern recognition is classification, which attempts to assign each input value to one of a given set of classes...
with his first Ph.D. student, Rangasami L. Kashyap
Rangasami L. Kashyap
Rangasami L. Kashyap is an Indian applied mathematician and a Professor of Electrical Engineering at Purdue University.He developed the Ho-Kashyap rule, an important result in pattern recognition....
.
Game theory
Turning his attention to game theoryGame theory
Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...
, Ho in 1965 published the paper Differential Games and Optimal Pursuit-Evasion Strategies, that proved the optimality of a proportional guidance scheme. His paper Nonzero Sum Differential Games was an influential game-theoretic study in systems and control, following earlier work by Samuel Karlin
Samuel Karlin
Samuel Karlin was an American mathematician at Stanford University in the late 20th century.Karlin was born in Yanova, Poland and immigrated to Chicago as a child...
, for example.
Discrete event dynamic systems
Since the 1970s, Ho focused on research in discrete event dynamic systemDiscrete event dynamic system
In control engineering, a discrete event dynamic system is a discrete-state, event-driven system of which the state evolution depends entirely on the occurrence of asynchronous discrete events over time...
s, making contributions in perturbation analysis and ordinal optimization
Ordinal optimization
In mathematical optimization, ordinal optimization is the maximization of functions taking values in a partially ordered set . Ordinal optimization has applications in the theory of queuing networks.- Mathematical foundations :...
, including the book Perturbation Analysis of Discrete Event Dynamic Systems.