Yu-Chi "Larry" Ho (; born March 1, 1934) is a

Chinese-American Chinese Americans are Americans of Chinese ancestry. Chinese Americans constitute a subgroup of East Asian Americans which also constitute a subgroup of Asian Americans. Many Chinese Americans have ancestors from mainland China, Hong Kong ...

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

control theorist Control theory is a field of control engineering and applied mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system ...

, and a

professor Professor (commonly abbreviated as Prof.) is an Academy, academic rank at university, universities and other tertiary education, post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin ...

at the School of Engineering and Applied Sciences,

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

. He is the co-author of ''Applied Optimal Control'', and an influential researcher in

differential game In game theory, differential games are dynamic games that unfold in continuous time, meaning players’ actions and outcomes evolve smoothly rather than in discrete steps, and for which the rate of change of each state variable—like position, spe ...

pattern recognition Pattern recognition is the task of assigning a class to an observation based on patterns extracted from data. While similar, pattern recognition (PR) is not to be confused with pattern machines (PM) which may possess PR capabilities but their p ...

, and

discrete event dynamic system In control engineering, a discrete-event dynamic system (DEDS) is a discrete-state, event-driven system of which the state evolution depends entirely on the occurrence of asynchronous discrete events over time. Although similar to continuous-variab ...

s. Ho was elected a member of the

National Academy of Engineering The National Academy of Engineering (NAE) is an American Nonprofit organization, nonprofit, NGO, non-governmental organization. It is part of the National Academies of Sciences, Engineering, and Medicine (NASEM), along with the National Academ ...

in 1987 for pioneering and sustained contributions to applied optimization, control, and systems engineering theory and application.

Biography

Education

Yu-Chi Ho was born on March 1, 1934, in

Shanghai Shanghai, Shanghainese: , Standard Chinese pronunciation: is a direct-administered municipality and the most populous urban area in China. The city is located on the Chinese shoreline on the southern estuary of the Yangtze River, with the ...

, China, and left home at the age of 15 in 1949 to complete his high school education in Hong Kong. In 1950, Ho was accepted to the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

and came to the U.S., where he received a B.S. in

electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

in the summer of 1953, at the age of 19. Ho later reported that his initial interests were in

mechanical engineering Mechanical engineering is the study of physical machines and mechanism (engineering), mechanisms that may involve force and movement. It is an engineering branch that combines engineering physics and engineering mathematics, mathematics principl ...

, 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. A Master of Science (; abbreviated MS, M.S., MSc, M.Sc., SM, S.M., ScM or Sc.M.) is a master's degree. In contrast to the Master of Arts degree, the Master of Science degree is typically granted for studies in sciences, engineering and medicine ...

degree in

in 1955. After working for

Bendix Aviation Bendix Corporation is an American manufacturing and engineering company founded in 1924 and subsidiary of Knorr-Bremse since 2002. During various times in its existence, Bendix made automotive brake shoes and systems, vacuum tubes, aircraft ...

for three years, Ho moved to

in 1958, where he completed a Ph.D. in

applied mathematics Applied mathematics is the application of mathematics, mathematical methods by different fields such as physics, engineering, medicine, biology, finance, business, computer science, and Industrial sector, industry. Thus, applied mathematics is a ...

in 1961. His thesis ''A Study of the Optimal Control of Dynamic Systems'' was advised by Arthur E. Bryson, Jr. and Kumpati S. Narendra.

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 The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas, United States. Founded in 1883, it is the flagship institution of the University of Texas System. With 53,082 students as of fall 20 ...

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 Tsinghua University (THU) is a public university in Haidian, Beijing, China. It is affiliated with and funded by the Ministry of Education of China. The university is part of Project 211, Project 985, and the Double First-Class Constructio ...

. In his career, he has supervised 50 Ph.D. students at Harvard and 3 students at Tsinghua.

Professional activities

Yu-Chi Ho is a member of the U.S.

and a foreign member of the

Chinese Academy of Engineering The Chinese Academy of Engineering (CAE, ) 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. The CAE and the Chinese Academy of Sciences a ...

and the

Chinese Academy of Sciences The Chinese Academy of Sciences (CAS; ) is the national academy for natural sciences and the highest consultancy for science and technology of the People's Republic of China. It is the world's largest research organization, with 106 research i ...

. He is also an

IEEE The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) organization, 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The 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 Automation describes a wide range of technologies that reduce human intervention in processes, mainly by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machine ...

. 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 Guggenheim Fellowships are Grant (money), grants that have been awarded annually since by the John Simon Guggenheim Memorial Foundation, endowed by the late Simon Guggenheim, Simon and Olga Hirsh Guggenheim. These awards are bestowed upon indiv ...

(1970) * IEEE Control Systems Science and Engineering Award (1989) * Chiang Technology Achievement Award (1993) * Richard E. Bellman Control Heritage Award from the

American Automatic Control Council The American Automatic Control Council (AACC) is an organization founded in 1957 for research in control theory. AACC is a member of the International Federation of Automatic Control (IFAC) and is an association of the control systems divisions of ...

(1999) *

Rufus Oldenburger Medal The 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 O ...

from the

American Society of Mechanical Engineers The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing edu ...

(1999) * 2002 class of

Fellow A fellow is a title and form of address for distinguished, learned, or skilled individuals in academia, medicine, research, and industry. The exact meaning of the term differs in each field. In learned society, learned or professional society, p ...

s of the

Institute for Operations Research and the Management Sciences The Institute for Operations Research and the Management Sciences (INFORMS) is an international society for practitioners in the fields of operations research Operations research () (U.S. Air Force Specialty Code: Operations Analysis), often s ...

* Isaacs Award from the International Society of Dynamic Games (2004) * Member, US

* Foreign member, China Academy of Engineering * Foreign member, China Academy of Sciences

Personal life

Ho became a naturalized citizen of the United States in 1961. He and his wife Sophia have three children, six grand children, and one great-grandchild. They currently reside in

Lexington, Massachusetts Lexington is a suburban town in Middlesex County, Massachusetts, United States, located 10 miles (16 km) from Downtown Boston. The population was 34,454 as of the 2020 United States census, 2020 census. The area was originally inhabited by ...

. 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.

Work

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 domain In mathematics and signal processing, the time domain is a representation of how a signal, function, or data set varies with time. It is used for the analysis of mathematical functions, physical signals or time series of economic or environmental ...

. Ho collaborated with

Rudolf E. Kálmán Rudolf Emil Kálmán (May 19, 1930 – July 2, 2016) was a Hungarian-American electrical engineer, mathematician, and inventor. He is most noted for his co-invention and development of the Kalman filter, a mathematical algorithm that is widely ...

, a pioneer of

modern control theory Modern may refer to: History *Modern history ** Early Modern period ** Late Modern period *** 18th century *** 19th century *** 20th century ** Contemporary history * Moderns, a faction of Freemasonry that existed in the 18th century Philosoph ...

. Before Kálmán, time series analysis and

classical control theory Classical control theory is a branch of control theory that deals with the behavior of dynamical systems with inputs, and how their behavior is modified by feedback, using the Laplace transform as a basic tool to model such systems. The usual ob ...

studied the

frequency domain In mathematics, physics, electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency (and possibly phase), rather than time, as in time ser ...

, using

harmonic analysis Harmonic analysis is a branch of mathematics concerned with investigating the connections between a function and its representation in frequency. The frequency representation is found by using the Fourier transform for functions on unbounded do ...

, especially

Laplace Pierre-Simon, Marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French polymath, a scholar whose work has been instrumental in the fields of physics, astronomy, mathematics, engineering, statistics, and philosophy. He summariz ...

and

Fourier transform In mathematics, the Fourier transform (FT) is an integral transform that takes a function as input then outputs another function that describes the extent to which various frequencies are present in the original function. The output of the tr ...

s. Kálmán developed the study of the

using state-space models. Joining Kálmán, Ho showed that the

state-space representation In control engineering and system identification, a state-space representation is a mathematical model of a physical system that uses state variables to track how inputs shape system behavior over time through first-order differential equations o ...

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 In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathem ...

. Their paper ''controllability of linear dynamic systems'', developed the theory of

controllability Controllability is an important property of a control system and plays a crucial role in many regulation problems, such as the stabilization of unstable systems using feedback, tracking problems, obtaining optimal control strategies, or, simply p ...

(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

with his first Ph.D. student, Rangasami L. Kashyap.

Game theory

Turning his attention to

game theory Game theory is the study of mathematical models of strategic interactions. It has applications in many fields of social science, and is used extensively in economics, logic, systems science and computer science. Initially, game theory addressed ...

, 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 (June 8, 1924 – December 18, 2007) was an American mathematician at Stanford University in the late 20th century. Education and career Karlin was born in Janów, Poland and immigrated to Chicago as a child. Raised in an Orthodo ...

, for example.

Discrete event dynamic systems

Since the 1970s, Ho focused on research in

s, making contributions in

perturbation analysis In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middle ...

and ordinal optimization, including the book ''Perturbation Analysis of Discrete Event Dynamic Systems''. and the book "Ordinal Optimization - Soft Optimization for Hard Problems" (Springer 2007)

Publications

Books

* * *

About Yu-Chi Ho's work

References

External links

Home Page at Harvard University

Mathematics Genealogy Project profile
*
Sciencenet.cn Blog
*
Biography of Yu-Chi Ho
from the Institute for Operations Research and the Management Sciences {{DEFAULTSORT:Ho, Yu-Chi 1934 births Living people Scientists from Shanghai American control theorists Chinese emigrants to the United States Richard E. Bellman Control Heritage Award recipients Nanyang Model High School alumni Harvard University alumni Harvard John A. Paulson School of Engineering and Applied Sciences faculty MIT School of Engineering alumni Members of the United States National Academy of Engineering Foreign members of the Chinese Academy of Sciences Foreign members of the Chinese Academy of Engineering Fellows of the Institute for Operations Research and the Management Sciences Bendix Corporation people