Thomas Nathaniel Hibbard (March 14, 1929 – February 11, 2016) was an American

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, structure, space, models, and change. History On ...

and

computer scientist A computer scientist is a person who is trained in the academic study of computer science. Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus (al ...

. Thomas N. Hibbard received the B.S. degree in physics from

Pacific University Pacific University is a private university in Forest Grove, Oregon. Founded in 1849 as the Tualatin Academy, the original Forest Grove campus is west of Portland. The university maintains three other campuses in Eugene, Hillsboro, and Wood ...

, Forest Grove, OR, in 1951, the M.S. degree in mathematics from the

University of Illinois The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the University ...

, Urbana, in 1954, and the Ph.D. degree in mathematics from the

University of California The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, ...

, Los Angeles, in 1966. From 1955 to 1958 T. N. Hibbard was a Scientific Programmer at the

RAND Corporation The RAND Corporation (from the phrase "research and development") is an American nonprofit global policy think tank created in 1948 by Douglas Aircraft Company to offer research and analysis to the United States Armed Forces. It is financed ...

, Santa Monica, CA, programming the

JOHNNIAC The JOHNNIAC was an early computer built by the RAND Corporation (not Remington Rand, maker of the contemporaneous UNIVAC I computer) and based on the von Neumann architecture that had been pioneered on the IAS machine. It was named in honor of v ...

, an early computer built by Rand, and from 1959 to 1965 a member of the research staff of the

System Development Corporation System Development Corporation (SDC) was a computer software company based in Santa Monica, California. Founded in 1955, it is considered the first company of its kind. History SDC began as the systems engineering group for the SAGE air-defense ...

, Santa Monica, CA, where he worked with

Seymour Ginsburg Seymour Ginsburg (December 12, 1927 – December 5, 2004) was an American pioneer of automata theory, formal language theory, and database theory, in particular; and computer science, in general. His work was influential in distinguishing theor ...

and

Joseph Ullian Joseph is a common male given name, derived from the Hebrew Yosef (יוֹסֵף). "Joseph" is used, along with "Josef", mostly in English, French and partially German languages. This spelling is also found as a variant in the languages of the mo ...

automata theory Automata theory is the study of abstract machines and automata, as well as the computational problems that can be solved using them. It is a theory in theoretical computer science. The word ''automata'' comes from the Greek word αὐτόματο� ...

and

formal languages In logic, mathematics, computer science, and linguistics, a formal language consists of string (computer science), words whose symbol (formal), letters are taken from an alphabet (formal languages), alphabet and are well-formedness, well-formed ...

. Following a three-year visiting faculty appointment at the Catholic University of

Salta Salta () is the capital and largest city in the Argentine province of the same name. With a population of 618,375 according to the 2010 census, it is also the 7th most-populous city in Argentina. The city serves as the cultural and economic ce ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, he joined the

University of Southern California The University of Southern California (USC, SC, or Southern Cal) is a Private university, private research university in Los Angeles, California, United States. Founded in 1880 by Robert M. Widney, it is the oldest private research university in C ...

, Los Angeles, as an assistant professor of Computer Science in 1970. He conducted research in searching,

sorting Sorting refers to ordering data in an increasing or decreasing manner according to some linear relationship among the data items. # ordering: arranging items in a sequence ordered by some criterion; # categorizing: grouping items with similar pro ...

, and

data structures In computer science, a data structure is a data organization, management, and storage format that is usually chosen for efficient access to data. More precisely, a data structure is a collection of data values, the relationships among them, a ...

, helping to pioneer the field of analysis of algorithms. In 1974, he started research with his then faculty colleague

Armin B. Cremers Armin Bernd Cremers (born June 7, 1946) is a German mathematician and computer scientist. He is a professor in the computer science institute at the University of Bonn, Germany. He is most notable for his contributions to several fields of discre ...

, initiating the theory and applications of data spaces. In February 1976, he joined the staff of the

Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

, Pasadena, CA, working on the Voyager,

IRAS The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

and

Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...

projects until his retirement from JPL in 1986. At that time, he joined the

Information Sciences Institute The USC Information Sciences Institute (ISI) is a component of the University of Southern California (USC) Viterbi School of Engineering, and specializes in research and development in information processing, computing, and communications techno ...

(ISI), Marina del Rey, CA, and did experimental research on

parallel computing Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different fo ...

until 1989, when he returned to Salta, Argentina, to teach at the

National University A national university is mainly a university created or managed by a government, but which may also at the same time operate autonomously without direct control by the state. Some national universities are associated with national cultural or po ...

(UNSA).

Contributions to Computer Science

Hibbard was a co-inventor of the

binary search tree In computer science, a binary search tree (BST), also called an ordered or sorted binary tree, is a rooted binary tree data structure with the key of each internal node being greater than all the keys in the respective node's left subtree and ...

. He first proposed the so-called Hibbard deletion for binary search trees, in which the node to be deleted is replaced by its successor . Hibbard proposed one of several widely cited increment sequences for the

Shellsort Shellsort, also known as Shell sort or Shell's method, is an in-place comparison sort. It can be seen as either a generalization of sorting by exchange ( bubble sort) or sorting by insertion (insertion sort). The method starts by sorting pairs o ...

algorithm.

Selected publications

References

External links

''Publications of Thomas N. Hibbard''
in the dblp computer science bibliography. {{DEFAULTSORT:Hibbard, Thomas N. 2016 deaths 1929 births Computer scientists 20th-century American mathematicians Pacific University alumni 21st-century American mathematicians University of Illinois Urbana-Champaign alumni University of California, Los Angeles alumni RAND Corporation people Jet Propulsion Laboratory faculty